WO2024086892A1 - Stable api formulations comprising micronized tobramycin - Google Patents

Abstract

Described are methods of manufacturing a dry powder pharmaceutical API combination formulation for orogastric topical application comprising the step of: blending micronized tobramycin with one or more additional active pharmaceutical ingredients, as well as dry powder pharmaceutical API combination formulations, reconstituted liquid formulations and/or pastes comprising same, and uses thereof.

Description

STABLE API FORMULATIONS COMPRISING MICRONIZED TOBRAMYCIN

Field of the invention

The invention is concerned with providing methods for manufacturing stable API blends of colistin, tobramycin and nystatin for use in GMP manufacture of drug products for preventing hospital acquired infections.

Background

Sepsis, the body's life-threatening response to infection, is a common cause of death in critically ill patients who are mechanically ventilated in Intensive Care Units (ICUs). A quarter of patients that develop severe sepsis die during their hospitalisation.

Selective Decontamination of the Digestive Tract (SDD) is an infection-control strategy involving the use of antibiotics that is designed to reduce the risk of infection and improve survival for critically ill patients. SDD involves the application of an antibiotic paste to the mouth, throat, stomach and concurrent administration of a short course of intravenous antibiotics. Mortality is reduced through reducing sepsis by altering the balance of potentially pathogenic organisms and normal gastrointestinal flora. In particular, an object is to eradicate aerobic Gram-negative bacilli and pathogenic fungi from the digestive tract while maintaining normal populations of Gram-positive and anaerobic bacteria. The mechanism by which SDD prevents infection is primarily by decreasing gastric colonisation of these organisms whilst avoiding subsequent micro aspiration into the lungs, and possibly stopping direct translocation of these organisms through the bowel mucosa.

The evidence supporting the use of SDD for saving lives and preventing infections is quite strong. However, health care professionals in many parts of the world have refrained from using SDD due to fears of the effects of overuse of antibiotics on the frequency of infections with resistant bacteria such as multi-resistant Gram negative organisms, MRSA and Clostridium difficile. Another difficultly is that there are no good manufacturing practice (GMP) manufactured products available on the market that have proven stability and efficacy. Instead, drugs for implementing various SDD protocols are compounded on an as needed basis in the hospital pharmacy setting.

The SuDDICU clinical trial (now completed and published on 26 October 2022) was an international, multicentre, crossover, cluster RCT (x-cRCT) of eligible patients receiving mechanical ventilation in participating intensive care units (ICUs) whereby the primary outcome aimed to determine if the systematic delivery of SDD to critically ill patients within an ICU reduced hospital mortality and the second outcome included an ecological assessment and a long-term health economic analysis. SuDDICU was recruiting 10,000-15,000 patients across 40-50 ICUs in Australia, UK and Canada. All patients eligible for the intervention were to receive the following in addition to the usual infection control measures: • A six-hourly topical application of 0.5g paste containing colistin lOmg, tobramycin lOmg and nystatin 125,000 I U, to the buccal mucosa and oropharynx;

• A six-hourly administration of 10 mL of a suspension containing 100 mg colistin, 80 mg tobramycin and 2 x 10⁶ III nystatin, to the gastrointestinal tract via a gastric/post-pyloric tube;

• A four-day course of an IV antibiotic.

Medicaments suitable for use in at least the SuDDICU trial and that address one or more of the above problems or at least provide a useful alternative are therefore desirable.

It is a preferred aspect of the present invention to provide medicaments, particularly a GMP quality paste for buccal administration and a GMP-quality suspension for oral administration, to be used in the outlined steps of the SDD clinical trial, and which are suitably standardised to support the SuDDICU clinical trial. GMP quality products ensures safe and stable products with reproducibility in the medicinal product, whereby every batch made is reliably the same and leads to reproducibility in clinical result.

A reference herein to a patent document or any other matter identified as prior art, is not to be taken as an admission that the document or other matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Where any or all of the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components.

Statements of the invention

In a first aspect, the invention provides a method of manufacturing a dry powder pharmaceutical API combination formulation comprising the step of: blending micronized tobramycin with one or more additional active pharmaceutical ingredients. Preferably, the one or more additional active pharmaceutical ingredients are selected from colistin and nystatin, most preferably a combination of colistin and nystatin. Suitably, the micronized tobramycin has a top cut d(98) of about 100 microns or less.

In a second aspect, the invention provides a dry powder pharmaceutical API combination formulation obtainable by the method of the first aspect.

In a third aspect, the invention provides a dry powder pharmaceutical API combination formulation comprising micronized tobramycin, colistin and nystatin. Suitably, the micronized tobramycin is in particulate form, wherein the particles have a size distribution with a top cut d(98) of about 100 microns or less. In a fourth aspect, the invention provides a dry powder formulation according to the third aspect, preferably which is formulated for reconstitution as a liquid suspension, for example with purified or distilled water, or any other suitable liquid for reconstituting liquid pharmaceutical products.

In a fifth aspect, the invention provides a liquid suspension reconstituted from the dry powder formulation of the second to fourth aspects, preferably reconstituted with water, such as purified or distilled water.

In a sixth aspect, the invention provides a paste comprising a blend of micronized tobramycin, colistin and nystatin components, or any other suitable liquid for reconstituting liquid pharmaceutical products. Suitably, the micronized tobramycin is in particulate form, wherein the particles have a size distribution with a top cut d(98) of about 100 microns or less.

In a seventh aspect, the invention provides a kit comprising a plurality of doses of one or more of a dry powder formulation according the second to fourth aspects and a paste according to the sixth aspect. Suitably, the micronized tobramycin is in particulate form, wherein the particles have a size distribution with a top cut d(98) of about 100 microns or less.

In an eighth aspect, the invention provides for a use of micronized tobramycin as a component in a dry powder combination formulation for prevention of hospital acquired infection and/or sepsis. Suitably, the micronized tobramycin is in particulate form, wherein the particles have a size distribution with a top cut d(98) of 100 microns or less.

In a ninth aspect, the invention provides for a use of micronized tobramycin as a component in a dry powder combination formulation for reconstitution to a liquid suspension. Suitably, the micronized tobramycin is in particulate form, wherein the particles have a size distribution with a top cut d(98) of about 100 microns or less.

In a tenth aspect, the invention provides for a use of micronized tobramycin in the manufacture of a medicament for the prevention of hospital acquired infection and/or sepsis. Suitably, the micronized tobramycin is in particulate form, wherein the particles have a size distribution with a top cut d(98) of about 100 microns or less.

In an eleventh aspect, the invention provides for a use of a dry powder formulation according the second to fourth aspects in the manufacture of a medicament for the prevention of hospital acquired infection and/or sepsis.

In a twelfth aspect, the invention provides for a method of preventing a hospital acquired infection and/or sepsis comprising the steps of topical administering to the respiratory tract of a subject in needed thereof, a therapeutically effective amount of one or more of a reconstituted dry powder formulation according to the second to fourth aspects and a paste according to the sixth aspect.

Particle size parameters are preferably determined from laser diffraction particle size distribution studies, for example, using a Malvern Mastersizer 2000 instrument, preferably with a Sicirocco dry powder feeder attachment used in the analysis method.

The particle size/volume distribution curve is determined, for example, using a feed rate of powder feeder of 65, suitably at a disperser pressure of 3 bar. In some embodiments, the calculation model used is the Fraunhofer method.

In general, a typical batch of non-micronized tobramycin may have a D(10) of about 7.5 micron or more. Some batches may have a D(50) of about 40 microns or more. Some batches may have a D(90) of about 150 microns. Typically, in most batches, the top cut D(98) for the non-micronized tobramycin may be about 200 microns or more, meaning that 98% of the particles are smaller than about the stated value. Typical specific surface area may be measured at up to about 0.5 m²/g. Typically, for some batches, the surface weighted mean D[3,2] may be about 15 or higher microns. In some batches the volume weighted mean D[4,3] may be about 90 or higher. About means ±0.5%.

For example, one particular batch of non-micronized tobramycin has the following typical particle size parameters: D(10), D(50), D(90) for this batch of non-micronized tobramycin are approx. 10 microns, 57 microns and 189 microns respectively. A typical a top cut D(98) for the non-micronized tobramycin in this batch is about 300 microns, meaning that 98% of the particles are smaller than the state size. In this batch, the specific surface area is measured at 0.278 m²/g, while the surface weighted mean D[3,2] is 21.585 microns and the volume weighted mean D[4,3] is about 189 microns. About means ±0.5%.

In another batch of non-micronized tobramycin, D(10), D(50), D(90) for this batch of non- micronized tobramycin are approx. 13 microns, 66 microns and 215 microns respectively. The top cut D(98) for the non-micronized tobramycin is about 378 microns, meaning that 98% of the particles are smaller than about 378 microns. In this batch, the specific surface area is measured at 0.219 m²/g. The surface weighted mean D[3,2] is about 27.5 microns and the volume weighted mean D[4,3] is about 96 microns. About means ±0.5%.

According to the present invention, the tobramycin is micronized, preferably prepared with or under pressurised air, though any particle micronization technique can be used as long as the resultant particle size distributions are within the parameters described herein and which may be determined by laser particle size distribution analysis.

In the case of the micronized batch, the particle size distribution may be analysed by a laser diffraction technique, e.g., as described above. Micronized tobramycin sulfate is particularly preferred.

In general, in some embodiments, a typical batch of micronized tobramycin, may have a D(10) of about 7 microns or less. In some embodiment, the batch may have a D(50) of about 35 microns or less. In some embodiment, the batch may have a D(90) of about 145 microns or less. In one embodiment, the batch of micronized tobramycin has a D(10) of about 7 microns or less, a D(50) of about 35 microns or less and a D(90) of about 145 microns or less.

Suitably, in some embodiments, the top cut D(98) for the micronized tobramycin is typically about 150 microns or less, 100 microns or less, 90 microns or less, 80 microns or less, 70 microns or less, 60 microns or less, 50 microns or less, or 40 microns or less, meaning that 98% of the particles are smaller than about the stated value. In some embodiments, the top cut D(98) is greater that about 30 microns, or is from about 150 microns to about 30 microns, or from about 100 microns to about 30 microns, or from about 50 microns to about 30 microns. In some embodiments, a typical specific surface area may be measured at about 0.225 m²/g or less. In some embodiments, the surface weighted mean D[3,2] may be up to and including about 10 microns, up to and including about 7.5 microns, up to and including about 5 microns. In some embodiments, the volume weighted mean D[4,3] may be up to and including about 60 microns, up to and including about 50 microns, or up to and including about 40 microns. In some embodiments, D[4,3] is greater than about 30 microns. About means ±0.5%.

In an example batch of micronized tobramycin, the D(10), D(50), D(90) are about 2 microns, about 11 microns and about 28.5 microns, respectively. The top cut D(98) for the non-micronized tobramycin is about 46 microns, meaning that 98% of the particles are smaller than about 46.5 microns. The specific surface area is measured at about 1.52 m²/g. The surface weighted mean D[3,2] is about 4 microns. The volume weighted mean D[4,3] is about 14 microns.

In another example batch of micronized tobramycin, the D(10), D(50), D(90) are about 3.5 microns, about 16 microns and about 37 microns respectively. The top cut D(98) for the non- micronized tobramycin is about 53.5 microns, meaning that 98% of the particles are smaller than the stated value. The specific surface area is measured at 1.08 m²/g. The surface weighted mean D[3,2] is 5.567 microns and the volume weighted mean D[4,3] is 18.369 microns.

The D(98) is a particular parameter of interest as it reflects the overall diameter cut off for the majority of the particles. It will be appreciated that there is a significant difference between a D(98) of 200 microns or more, and a D(98) for micronized tobramycin of 100 microns or less.

Brief description of the drawings

Figure 1 illustrates (a) the product specification for n SDD Oral Paste according to a preferred embodiment of the invention provided in a syringe and stored between 2 and 8 °C; (b) a product specification for the SDD Oral Paste of (a) showing the specification, purpose and concentration for each of the ingredients;

Figure 2 illustrates (a) the product specification for an SDD Gastric Powder for Suspension according to a preferred embodiment of the invention and stored between 2 and 8 °C; (b) a product specification for the SDD Gastric Powder for Suspension of (a) showing the specification, purpose and concentration for each of the ingredients;

Figure 3 illustrates %RSD of 7 tobramycin assay results as part of a mixing trial carried out on the SDD Gastric Powder for Suspension API blend corresponding to Batch No.'s 1809005 and 1812002, whereby the mixing studies are carried out on samples of a reconstituted liquid suspension in water or saline from bulk powder from a batch under investigation.

Figure 4 illustrates active assay results for reconstituted suspension samples of the SDD Gastric Powder for Suspension taken from Batch No. 1809005 at the start, middle and end of the batch after container filling on finished products;

Figure 5 illustrates the suspension thickening studies involving adjustment of concentration of suspending agent in the SDD Gastric Powder for Suspension (see Example 3);

Figure 6 illustrates thickened suspension and adherence to the containers during the study reported in Example 3: (a) Separation of suspension: overnight separation of suspension was observed in both formulation B and formulation C; (b) Remaining product in formulation B: product remaining in the bottle of the formulation B sample stored at 25 °C at the conclusion of the 5-day study; (c) Remaining product in formulation A: product remaining in the bottle of the formulation A sample stored at 25 °C at the conclusion of the 5-day study;

Figure 7 illustrates a testing trend card comparing assay results for 11 separate batches of the SDD Oral Paste product according to certain embodiments of the invention, including viscosity information; Figure 8 illustrates laser diffraction particle size distribution studies of the raw material tobramycin (Ref: 17L15-B01-344197) that has not been subjected to micronization, using a Malvern Mastersizer 2000 instrument with a Sicirocco dry powder feeder attachment used in the analysis method. The particle size/volume distribution curve is shown together with the relevant processing parameters and Data Table. The feed rate of the powder feeder is 65 at a disperser pressure of 3 bar. The calculation model used is the Fraunhofer method. Obscuration is 1.08%. Weighted Residual is 1.622%. D(10), D(50), D(90) for this non-micronized tobramycin are 10.12 microns, 57.348 microns and 189.049 microns respectively. The top cut D(98) for the non-micronized tobramycin is about 300 microns, meaning that 98% of the particles are smaller than 300 microns. The specific surface area is measured at 0.278 m²/g. The surface weighted mean D[3,2] is 21.585 microns and the volume weighted mean D[4,3] is 189.049 microns; Figure 9 illustrates laser diffraction particle size distribution studies of a batch of micronized tobramycin (micronization of the raw material having Ref: 17L15-B01-344197, and obtained from Fagron), using a Malvern Mastersizer 2000 instrument with a Sicirocco dry powder feeder attachment used in the analysis method. The particle size/volume distribution curve is shown together with the relevant processing parameters and Data Table. The feed rate of the powder feeder is 65 at a disperser pressure of 3 bar. The calculation model used is the Fraunhofer method. Obscuration is 3.64%. Weighted Residual is 0.103%. D(10), D(50), D(90) for this micronized tobramycin are 2.068 microns, 10.822 microns and 28.749 microns respectively. The top cut D(98) for the micronized tobramycin is about 46.373 microns, meaning that 98% of the particles are smaller than 46.373 microns. The specific surface area is measured at 1.52 m²/g- The surface weighted mean D[3,2] is 3.958 microns and the volume weighted mean D[4,3] is 13.751 microns;

Figure 10 illustrates laser diffraction particle size distribution studies of the raw material tobramycin (Ref: 20031047001) that has not been subjected to micronization, using a Malvern Mastersizer 2000 instrument with a Sicirocco dry powder feeder attachment used in the analysis method. The particle size/volume distribution curve is shown together with the relevant processing parameters and Data Table. The feed rate of the powder feeder is 65 at a disperser pressure of 3 bar. The calculation model used is the Fraunhofer method. Obscuration is 1.80%. Weighted Residual is 0.311%. D(10), D(50), D(90) for this non-micronized tobramycin are 12.963 microns, 64.473 microns and 214.735 microns respectively. The top cut D(98) for the non-micronized tobramycin is about 378.137 microns, meaning that 98% of the particles are smaller than 378.137 microns. The specific surface area is measured at 0.219 m²/g. The surface weighted mean D[3,2] is 27.404 microns and the volume weighted mean D[4,3] is 96.192 microns; and

Figure 11 illustrates laser diffraction particle size distribution studies of a batch of micronized tobramycin (micronization of the raw material having Ref: 20031047001, obtained from Fagron), using a Malvern Mastersizer 2000 instrument with a Sicirocco dry powder feeder attachment used in the analysis method. The particle size/volume distribution curve is shown together with the relevant processing parameters and Data Table. The feed rate of the powder feeder is 65 at a disperser pressure of 3 bar. The calculation model used is the Fraunhofer method. Obscuration is 2.43%. Weighted Residual is 0.150%. D(10), D(50), D(90) for this micronized tobramycin are 3.586 microns, 15.745 microns and 36.672 microns respectively. The top cut D(98) for the micronized tobramycin is 53.501 microns, meaning that 98% of the particles are smaller than 53.501 microns. The specific surface area is measured at 1.08 m²/g. The surface weighted mean D[3,2] is 5.567 microns and the volume weighted mean D [4,3] is 18.369 microns. Definitions

As used herein 'BP' means British Pharmacopoeia which provides quality standards and testing specification and directions for particular UK pharmaceutical substances and medicinal products.

As used herein 'PhEur' means European Pharmacopoeia 8th Edition which provides Europe's scientific and legal benchmark for pharmacopoeia standards, including quality standards and testing specification and directions.

As used herein, 'USP' means United States Pharmacopeia which provides the United States' established quality standards and testing specification and directions for manufacturing and supplying drugs worldwide.

Detailed description of the invention

Mechanically ventilated patients in the intensive care setting (ICH) are typically critically ill and are particularly susceptible to hospital acquired infections, including sepsis, which can lead to sepsis and death. Selective decontamination of the digestive tract (SDD) is an intervention for reducing infection rates and deaths in ventilated patients and involves application of an antibiotic paste to the mouth, throat and stomach of the patient together with administration of a short course of intravenous antibiotics.

The present invention provides methods for commercial manufacture of pharmaceutical formulations for selective decontamination of the digestive tract of mechanically ventilated ICU patients to prevent hospital acquired infections in critically ill patients which can lead to sepsis and death.

The pharmaceutical formations of the invention comprise a combination of antimicrobial APIs for topical application to the mouth, throat and/or stomach of the patient. The formulation for mouth and throat application are provided in the form of a viscous paste, while the formulation for application to the stomach in provided in the form of a liquid suspension that has a viscosity/consistency which is suitable for passage through a gastric delivery tube for adults (size ranging from 12 to 18 Fr). For optimal stability reasons, the liquid suspension is reconstituted at a patient's bedside on day one of administration. Thus, preferred products of the invention are supplied to a hospital in a dry powder form which is ready for reconstitution when ready for use. The invention extends to a modified liquid suspension product (and corresponding dry powder for reconstitution) for paediatric patients whose body size means very small diameter gastric tubes are used (e.g., 6 Fr size for neonates, 7 Fr size for infants up to 5 year old, 8 to 10 Fr for children over 5 years old. The modified liquid suspension product for paediatric patients is formulated to not stick to and/or block gastric tubes, even in the case where the liquid suspension is several days old (after reconstitution). It is highly desirable to avoid blockage of such tubes as replacing tubes is time consuming, and a potential safety issue due to insertion challenges.

Preferably, pharmaceutical formulations described herein comprise a combination of micronized tobramycin, colistin and nystatin as APIs. Suitably, the micronized tobramycin is in particulate form, wherein the particles have a size distribution with a top cut d(98) ranging from about 30 microns to about 100 microns.

The pharmaceutical formulations of micronized tobramycin, colistin and nystatin are provided in form that is suitable for topical administration to the mouth, throat and stomach of the patient. For example, in one aspect, the pharmaceutical formulation is provided as a liquid suspension of the antimicrobial API combination which is adapted for administration to the stomach of a patient via a gastric tube.

In another aspect, the pharmaceutical formulation is provided as liquid paste adapted for topical application to mouth and throat of the patient. Suitably, the liquid paste exhibits an average viscosity of from about 85,000 to 125,000 Cp at 20 °C. In some embodiment, the liquid paste exhibits an average viscosity of from about 110,000 to 115,000 Cp at 20 °C, preferably about 110,000 Cp at 20 °C.

Desirably, the pharmaceutical formulations are provided in the form of a pharmaceutical product, preferably a pharmaceutical product commercially manufactured in accordance with GMP principles including assay testing of one or more active pharmaceutical ingredients, such as described herein.

Most preferably, the pharmaceutical product is provided as a kit of parts which enable convenient bedside topical application of micronized tobramycin, colistin and nystatin to the mouth and throat and stomach of the patient in a hospital setting. The kit supports consistent and metered dosing of the antimicrobials to the patient through their treatment in accordance with the SDD protocol. Thus, the kit advantageously addresses variables and inconsistencies in current ad hoc methods of using this protocol in SSD.

Suitably, the kit may comprise at least one container comprising a dry powder blend of the micronized tobramycin, colistin and nystatin APIs which is ready for bedside reconstitution to a liquid suspension for administration to the patient's stomach. The kit preferably further comprises a plurality of containers of dosage forms which deliver consistent and metered doses of the liquid oral paste for bedside topical application of the micronized tobramycin, colistin and nystatin APIs to the mouth and throat of the patient. Preferably, the containers of dosage forms are single use dosage forms which ensure a consistent dose is applied every time. The invention has been developed as follows. For the first time, during manufacture of large- scale batch size quantities of a GMP compliant medicinal product to support the above mentioned SuDDICU clinical trial, a previously unrecognized separation/segregation problem was identified in the case of a dry powder blend consisting of an equilibrium homogeneous mixture of a combination of the active pharmaceutical ingredients (APIs) colistin, tobramycin and nystatin. After blending and mixing to form the homogenous dispersion of actives, it was found that the resultant dry power blend or dispersion of the tobramycin, colistin and nystatin API is extremely unstable. Indeed it was found that separation/segregation of the API components in the blend readily and rapidly occurs, even without agitation, in some cases, over a period of as little as 12 hours. Thus, once blending and mixing ceases, the APIs, particularly the tobramycin, begins to settle out of the homogeneous dispersion (so called 'un-mixing' or reduced homogeneity of the blend). This is a significant problem for manufacture of products using the API blend as a starting point as the active APIs in the blend very quickly become dispersed disproportionally throughout the blend. Such separation is exacerbated by actions/further processing involving movement including agitation and/or vibration. Such movement arises during further manufacturing or processing steps, including packaging, e.g., when the powder blend is passed through a powder dispensing machine for aliquot filing. The problem is so severe that relatively light forces result in fast settling, as does more gentle actions such as scooping by hand. Significant agitation results during transport of large volumes or quantities of the blend. The settling is particularly problematic for batch size manufacture as filling containers from the front of such a batch (e.g. at a discharge outlet) results in a large amounts of the smaller and lighter particles of the nystatin API than intended, whereas filing from the end of the batch would result in an excess of the heavier particles of tobramycin which tend to settle out as time passes.

The now recognised settling problem went previously unrealized as large-scale blends of these APIs have not been produced in this manner before. Furthermore, the ingredients or stability studies on such blends which are required in a GMP compliant manufacturing procedure have not been carried out prior to formulation of the GMP products of the present invention. Instead, conventionally, in a hospital pharmacy setting, compounding pharmacists would tailor make a paste or suspension for a ventilated patient on demand by dispensing a desired amount of colistin, tobramycin and nystatin directly into a single container where the settling problem went unrecognized. Furthermore, where a bench top size batch might have been made, it is not left standing subject to quality control testing. Instead, it would have been immediately dispensed into bottles over a short time of minutes to an hour or so and before significant separation would have occurred.

Large scale GMP batches are made in bulk for individual aliquot dispensing into containers or portions of a batch are taken for further mixing or processing. However, a bottle-by-bottle approach is not at all suitable for the batch sizes required for commercial manufacture of drug products. In contrast, during GMP compliant manufacturing, after API blending is complete, the blend sits idle while quality control/release testing is completed prior to the next phase of manufacture or dispensing and packaging. Until mixing trial studies were carried out as part of a quality control process, the API settling problem was not recognised. Thus, the present invention relates to provision of an inventive solution to a previously unrecognized problem in the art.

In order to solve the above problem, pharmaceutical grade tobramycin was subjected to a micronization process which serves to reduce the particle size distribution significantly. The average particle size, top cut, media cut, and other particle size distribution parameters of the micronized tobramycin described herein can be determined using methods and instruments known to the person skilled in the art and preferred characteristics are described herein. For example, laser diffraction particle analysers such as the Malvern Mastersizer 2000 can be used and give information on the average/mean particle size and particle size distribution (PSD) with respect to a volume particle size distribution of a sample. In preferred embodiments, the micronized tobramycin is supplied by Fagron Compounding Supplies Australia. Suitably, the micronized tobramycin is prepared with or under pressurised air, though any particle micronization technique can be used as long as the resultant particle size distributions are within the parameters described herein (and which may be determined by laser particle size distribution analysis).

On particle size distribution analysis by a laser diffraction technique, a typical pharmaceutical grade raw material tobramycin API (e.g. USP or BP standard) that is not micronized has a d(10) of about 10 microns, a d(50) of about 57 microns and a d(90) of about 189 microns and has a particle size distribution curve as shown herein (see Figure 8). From the corresponding Data Table in Figure 8, it is evident that the top cut d(98) is about 300 microns, meaning 98% of the particles are smaller than 300 microns. Another batch of pharmaceutical grade raw material tobramycin API (e.g. USP or BP standard) that is not micronized has a d(10) of about 13 microns, a d(50) of about 65 microns and a d(90) of about 215 microns and has a particle size distribution curve as shown herein (see Figure 10). The top cut d(98) for this batch is about 378 microns, meaning 98% of the particles are smaller than 378 microns.

In contrast, the micronized tobramycin described herein preferably has a top cut d(98) in the range of from about 30 microns to about 100 microns, more preferably from about 40 microns to about 60 microns, more preferably still from about 45 microns to about 55 microns, meaning that 98% of the particles after micronization are smaller than the micron value for d(98). "About" here means ±3%. This is a significant reduction in overall particle sizes in terms of the particle size distribution of the micronized tobramycin compared to raw tobramycin.

In preferred cases, the top cut D(98) of the particle size distribution as determined by laser particle diffraction particle analysis for raw micronization is reduced by 30% to 95%, 40% to 90%, 45% to 89.5%, 50% to 89%, 60% to 88%, 70% to 87%, 80% to 86%, 80% to 85%, or 80% to 84%.

Another useful parameter to consider is the volume moment mean D[4,3] which reflects the size of those particles which constitute the bulk of the sample volume. On particle size distribution analysis by a laser diffraction technique, a typical pharmaceutical grade raw material tobramycin API (e.g. USP or BP standard) that is not micronized has a D[4,3] of about 189 microns (see Figure 8). Another batch of pharmaceutical grade raw material tobramycin API (e.g. USP or BP standard) but not micronized has a D[4,3] of about 96 microns. In contrast, the micronized tobramycin described herein has D[4,3] of about 13.8 microns (see Figure 9) and in another batch has a D[4,3] of about 18.3.

In preferred cases, the D[4,3] of the particle size distribution as determined by laser particle diffraction particle analysis for raw micronization is reduced by 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or up to 99%. The reduction, for example, may be in result of a top cut D(98) parameter.

In some cases, the micronization process can result in more uniformly shaped tobramycin particles, for example, a spherical shape. A typical micronization process can involve any processes that reduce particle size/diameter, for example, milling. Typical mills include fluid energy mills such as a jet mill, or by mechanical means using high peripheral speed mills such as a pin mill, or ball or bead mills. In an agitator bead mill, grinding beads and agitating elements are used to reduce the API particle size through impact and shear. Jet milling reduces particle size through high velocity particleparticle collisions. Unmilled particles are introduced into the milling chamber while air or nitrogen is introduced via nozzles at high pressure which accelerates the solid particles to sonic velocities. The generated forces cause the particles collide and fracture. While being propelled about the mill, larger particles experience higher centrifugal forces and are forced to the outer perimeter of the mill. Small particles exit the mill through the central discharge stream. Depending on the pressure and powder feed rate, particles of down to 1 pm in diameter can be produced (Telko and Hickey, 2005). A pin mill uses mechanical impact to grind material, both by particle-particle and particle-solid collisions. A pin mill is equipped with a series of concentrically mounted pins located on a spinning rotor and stationary stator plate. The pin mill cannot produce particles as small as those from the jet mill (Drogemeier and Leschonski, 1996). The ball mill is rotating cylinder loaded with drug and "milling media" in the form of balls or beads that grind the material particles against each other as they tumble inside the mill. Other micronization processes involve spray drying, which converts a liquid feed into an atomised spray which contacts a hot gas that quickly evaporates droplets to form a dried particulate. Spray drying tends to form more spherical particles and more homogeneous particle size distributions. Additional micronization processes involve supercritical fluid techniques involving using a supercritical fluid as an extracting solvent.

That using micronized tobramycin in a dry powder blend led to a more stable blend in terms of much reduced tendency towards API separation during manufacture and shortly thereafter was a surprising finding, given the understanding that micronized particles can carry high amounts of electrostatic charge, and therefore tend to be very cohesive. The smaller the particles, the stronger the cohesive forces. Moreover, the micronization process can lead to increased adhesion between the particles. Micronized powders with high energetic surfaces show poor flow properties (Feeley et al., 1998).

Suitably, the micronized tobramycin is provided in suitable free acid or salt form. Preferred is micronized tobramycin sulfate. Most suitably, the micronized tobramycin is provided as tobramycin sulfate BP grade or tobramycin sulfate USP grade, which has been subjected to a micronization process to reduce the starting average particle diameter as described herein.

Thus, in one aspect of the invention, there is provided a method of manufacturing a dry powder pharmaceutical API combination formulation for use in the manufacture of a medicament for selective decontamination of the digestive tract in a mechanically ventilated patient. Successful selective decontamination of the digestive tract can prevent hospital acquired infection, sepsis and death in some patients.

The method of manufacturing the dry powder pharmaceutical API combination comprises the step of: blending micronized tobramycin with colistin and nystatin to form a dry powder blend of antimicrobial active pharmaceutical ingredients (APIs).

Used herein 'dry powder pharmaceutical API combination formulation' is also described interchangeably as an 'API blend', 'API dry powder blend' or a 'dry powder blend'.

The methods described herein are preferably carried out under GMP conditions. Thus, most desirably, the manufacture of the dry powder pharmaceutical API combination formulation is carried out under good manufacturing practice (GMP) conditions that result in a GMP product. GMP conditions ensure that each batch of the formulation or product is consistently produced and controlled according to quality standards, thereby ensuring consistent quality, safety and efficacy of therapeutic products in accordance with regulatory standards.

The inventors have found that using micronized tobramycin in a dry powder blend leads to a more stable dry powder blend in terms of much reduced tendency towards API separation during manufacture and shortly (after about 12 hours) thereafter. It has been found that API blends comprising micronized tobramycin stay as a homogenous dispersion of the API much longer that equivalent blends where regular/bulk tobramycin is used (i.e., tobramycin having an average particle diameter of about 450 microns).

It has been surprisingly found that use of micronized tobramycin in the combination formulation described herein addresses the settling/stability issues observed in bulk API formulations using non-micronized/regular grade tobramycin.

Suitably, the dry powder pharmaceutical API combination is manufactured in bulk. A bulk formulation is one which is manufactured, typically commercially manufactured, e.g., under GMP conditions, to give a batch size of a particular quantity or size. It will be understood that sample aliquots of a particular size are taken from throughout the bulk formulation of a particular batch and are dispensed and packaged into individual containers as desired to provide a number of required doses for patients. The batch size to be prepared may be selected to provide sufficient APIs to treat at least 25 patients, at least 50 patients, more preferably at least 100 patients and in some particularly preferred embodiments, more than 100 patients. Desirably, the minimum batch size of the API combination is at least 5 kg, more preferably at least 10 kg and in some embodiments at least 50 kg. In some embodiments, the batch size may be in a range suitable to manufacture 400 kits, or in some embodiments, 800 kits.

Suitably, the colistin is provided as colistin sulfate, preferably colistin sulfate BP grade or colistin sulfate USP grade, more preferably colistin sulfate BP grade.

Suitably, the nystatin is nystatin BP grade.

Notably, the colistin and/or the nystatin are not micronized and are used in a form that meet the preferred aforementioned specification/standards. For example, the colistin (preferably in form of colistin sulfate), has a preferred particle size of between 50 - 150 pm. Preferably, the nystatin is micronized to about 90% < 10 pm and about 99% < 16 pm.

Desirably, the manufacturing method further comprises a step of adding at least one preservative to the dry powder pharmaceutical combination or API blend. Desirably, the preservative can be a sorbate salt, such as potassium sorbate, which is added to the blend of the dry powder pharmaceutical combination formulation during manufacture.

A suitable activating acid, for example, citric acid, can be added to the blend to ensure the sorbate salt preservative functions correctly.

Inclusion of a suitable preservative system is advantageous as it means that the manufactured API blend meets the preservative efficacy testing (PET) (also known as antimicrobial effectiveness testing) required for GMP compliance and which is undertaken on an API batch as a quality control measure to ensure a pharmaceutical blend or product is not supportive of growth of such microorganisms. PET testing is required by British Pharmacopoeia (BP), European Pharmacopoeia (Ph. Eur.) and United States Pharmacopoeia (USP) standards. Details methods for carrying out PET testing are provided in such Pharmacopoeia/Compendia/Standards.

Suitably, the method further comprises the step of blending a suspending agent, for example, a starch or modified starch, such as SyrSpend® Alka, or SyrSpend® sf, preferably SyrSpend® sf buffered to pH 4. SyrSpend® sf is a preservative free pre-measured suspending base for reconstitution supplied by Fagron® Group BV. It comprises modified food starch, citric acid, sucralose and sodium citrate. The suspending agent is useful to ensure the liquid suspension remains as a homogenous dispersion in the reconstitution liquid for the entire treatment time.

Desirably, the manufacturing method further comprises a step of adding flavouring, mouth feel and/or taste masking agents, for example, such as cyclodextrin, sugar, dextrose, or magnasweet to a blend of the dry powder pharmaceutical API combination formulation. The APIs used in typical SDD protocols have a very unpleasant taste and/or mouth feel. Therefore, such further agents are desirable.

After the blending step(s) are completed, the method further comprises the step of subjecting the resultant dry powder pharmaceutical API combination formulation to quality control (QC) testing. QC tests include PET, mixing trials to ensure stability of dispersion and low RSD for actives tobramycin, colistin and nystatin, microbiological quality, viscosity testing, visual tests, etc.

The invention extends to a dry powder pharmaceutical API combination formulation comprising a dry blend of micronized tobramycin, colistin and nystatin components, for example obtained or obtainable by the manufacturing method of the invention described herein.

In the bulk powder, preferably, colistin sulfate is present in an amount of 10%w/w; Tobramycin sulfate is present at 8% w/w and Nystatin is present at 30% w/w of bulk powders.

Suitably, the dry powder pharmaceutical API combination formulation is a GMP compliant product.

Preferably, the dry powder pharmaceutical API combinations of the invention are a homogenous powder dispersion, preferably an equilibrium homogenous dispersion, of dry powder component, particularly the APIs, and more particularly the APIs with the various excipients and other components described herein.

Preferably the micronized tobramycin is homogenously dispersed throughout the API blend and remains so for longer compared to an equivalent blend that does not use micronized tobramycin.

In some embodiments, the micronized tobramycin is homogenously dispersed (and remains homogeneously dispersed) throughout the formulation for at least 12 hours, more preferably at least 24 hours, more preferably still for at least 36 hours after the blending step(s) have been completed. However, in preferred embodiments, the powder blend is packaged into its final containers within 12 hours.

Homogenously dispersed micronized tobramycin (homogenous dispersion throughout the formulation) is evidenced by an associated low relative standard deviation (RSD) for tobramycin assay during mixing trials. Mixing trials involving taking a plurality of samples from random locations throughout a batch or at random times as the blend is passed out from a discharge outlet. Typically, at least 5 samples, more preferably at least 6 samples, at least 7 samples, at least 8 samples, at least 9 samples, or at least 10 samples can be taken for the assay to determine the mean and RSD of the particular assay. A greater number of samples taken provides more statistically meaningful results.

Each sample taken for the mixing trial may be subjected to a tobramycin assay and the mean and relative standard deviation (RSD) between the assay results calculated. The size of the relative standard deviation (RSD) can be used as an indicator of the homogeneity of the tobramycin through the blend at the time of testing. It will be understood that RSD is the ratio of the standard deviation to the mean assay result. It will be further understood that RSD is an expression of the precision and repeatability of an assay.

The tobramycin assay can be carried out using any suitable analytical technique known to the skilled person, including a chromatographic assay, particularly an HPLC assay. In the case of a tobramycin HPLC assay during mixing trials, a low relative standard deviation (RSD) is one which is 10% or less in mixing trials, preferably 7.5% or less, more preferably 5% or less, more preferably 3% or less, and most preferably 2% or less. An exemplary tobramycin HPLC assay method is described elsewhere herein, though other suitably validated assay methods could also be used.

Preferred dry powder pharmaceutical combination formulations for orogastric topical application comprise one or more preservatives, particularly a preservative system such as a potassium sorbate/citric acid combination. Under GMP manufacturing requirements, there is a regulatory requirement that no inappropriate organisms inadvertently introduced during the manufacturing process can sustain themselves within the product or its packaging and which could result in spoilage and/or infection. Therefore, preservative efficacy testing (PET) (also known as antimicrobial effectiveness testing) is undertaken on the API batch as a quality control measure to ensure a pharmaceutical blend or product is not supportive of growth of such microorganisms. Indeed, PET testing is required by British Pharmacopoeia (BP), European Pharmacopoeia (Ph. Eur.) and United States Pharmacopoeia (USP) standards.

In the present case, it has been found that API blends without preservative do not meet GMP standard PET requirements. Thus, antimicrobial preservatives are preferably added to the blend to inhibit microorganism growth and to enable the blended product to meet the required PET requirements of a GMP manufactured product.

Suitably, the preferred dry powder pharmaceutical combination formulations further comprise a suspending agent, for example starch as described above, such as SyrSpend® Alka or SyrSpend® sf, preferably SyrSpend® sf buffered to pH 4.

Suitably, the preferred dry powder pharmaceutical combination formulations further comprise one or more flavouring and/or taste masking agents, for example, such as cyclodextrin, sugar, dextrose, or magnasweet to mask and/or improve the taste of the product.

In some embodiments, the gastric powder has a shelf life of up to 6 months when stored at 2- 8 °C. Advantageously, during use, the gastric powder can be stored in a temperature controlled room of less than 25 °C for up to one week. In some embodiments, shelf life can be determined based on a stability study carried out on the reconstituted suspension at 25 °C/60% RH for up to 4 weeks. The analytical tests used to confirm stability may include one or more of: appearance, pH, Nystatin assay, Colistin Sulfate assay, Tobramycin assay, microbiological quality (TAMC, TYMC, E. coli) and PET.

Gastric Powder for SDD Liquid Suspension

The liquid suspension is an aqueous liquid preparation containing the APIs as solid particles homogenously dispersed throughout a liquid phase, and in which the solid API particles are present in excess of their solubility. Some suspensions are prepared and ready for use, while others are solid mixtures intended for reconstitution before use with an appropriate vehicle. Preferred suspensions are those that exhibit a stable homogeneous dispersion for at least one week when stored at room temperature.

A preferred gastric powder for reconstitution comprises:

10 % w/w of colistin sulfate,

30% w/w of nystatin, and

8% w/w of micronized tobramycin sulfate, and the remainder of excipients.

A preferred gastric powder for reconstitution comprises:

100 mg/g of colistin sulfate,

300 mg/g of nystatin, and

80 mg/g of micronized tobramycin sulfate, and the remainder of excipients.

Once quality control tests are met, the API blend is filled and sealed into containers to provide a product ready for bedside reconstitution into a liquid suspension for topical administration to a patient's stomach via a gastric tube.

Thus, desirably, the method further comprises the step of filing suitable containers with predetermined aliquots or amounts of the dry powder blend to form a packaged final product for bedside reconstitution to a liquid suspension for administration to a patient's stomach via a gastric tube. Desirably, the filling step does not typically occur until all QC testing has been completed and all tests carried out meet the required standard.

A preferred container for reconstitution of the API blend comprises polyethylene terephthalate, although other container materials may be suitable. Desirably, the container comprises, or is adapted to engage with, a syringe filling adaptor. Suitably, a preferred container is provided with a child resistant screw cap.

SDD Reconstituted Liquid Suspension

When required for use, the final product containers with predetermined aliquots or amounts of the dry powder are made up to a liquid suspension by adding water or other suitable buffer solution.

Thus, invention provides a liquid suspension reconstituted from the dry powder blend which is preferably reconstituted with water, such as purified or distilled water, for example, to 200 mL.

A preferred liquid suspension when reconstituted, for example, to 200 mL, comprises:

9 to 13 mg/mL of colistin sulfate,

1.5 x 10⁶ to 2.5 x 10⁶ lU/mL of nystatin, and

6 to 12 mg/mL of micronized tobramycin sulfate.

A preferred liquid suspension when reconstituted comprises:

9.7 to 11 mg/mL of colistin sulfate,

1.9 x 10⁶ to 2.2 x 10⁶ lU/mL of nystatin, and

7.2 to 9.6 mg/mL of micronized tobramycin sulfate.

A preferred liquid suspension when reconstituted comprises:

10 mg/mL of colistin sulfate,

2 x 10⁶ lU/mL of nystatin, and

8 mg/mL of micronized tobramycin sulfate.

A particularly preferred liquid suspension when reconstituted to 200 mL comprises:

2 g of colistin sulfate,

40 MU of nystatin,

1.6 g of micronized tobramycin sulfate.

A particularly preferred liquid suspension when reconstituted to 200 mL comprises:

2 g of colistin sulfate,

40 MU of nystatin,

1.6 g of micronized tobramycin sulfate

9.10 g of SyrSpend® SF pH4 dry,

0.4 g of potassium sorbate, 0.572 g of citric acid monohydrate.

For paediatric patients (<16 years), preferably, the liquid suspension has a viscosity of 4,000 mPa.s or less. Such viscosities are preferred when small diameter gastric tubes are used, for example, for a paediatric patient, typically tube diameters vary from paediatric 8-12 F up to adult 14 -18 F.

A preferred liquid suspension when reconstituted comprises a suspending agent, such as SyrSpend® sf pH 4, preferably SyrSpend® sf pH 4 that meets USP specification. The formulation includes a suspending agent (SyrSpend® sf pH 4) to ensure that when the bottle is standing, the APIs are evenly dispersed after shaking between administrations to the patient, thereby preventing 'caking' on the bottom of the bottle.

A preferred liquid suspension when reconstituted comprises an acid to control the suspension pH to between pH 4 to pH 5. A suitable acid is citric acid monohydrate, preferably citric acid monohydrate that meets BP specification.

A preferred liquid suspension when reconstituted comprises potassium sorbate, preferably potassium sorbate that meets USP specification.

A preferred liquid suspension when reconstituted comprises 45.5 mg/ml of SyrSpend® sf pH 4, 2.86 mg/mL of citric acid monohydrate, and 2 mg/mL of potassium sorbate.

Particularly preferred liquid suspensions of the invention are stable for up to 8 weeks when stored at 2-8 °C, as indicated by a tobramycin assay having an RSD of <2%, or <1%.

Particularly preferred liquid suspensions of the invention are stable at or below 25 °C for up to 1 week, as indicated by tobramycin assay having an RSD as described above.

A particularly preferred liquid suspension on reconstitution comprises:

10 mg/mL of colistin sulfate,

2 x 10⁶ lU/mL of nystatin, and

8 mg/mL of micronized tobramycin sulfate,

45.5 mg/mL of SyrSpend® sf pH 4,

2.86 mg/mL of citric acid monohydrate, and

2 mg/mL of potassium sorbate.

In one particularly preferred embodiment, the liquid suspension, on reconstitution comprises a reduced amount of SyrSpend® sf pH. For example, the liquid suspension may, on reconstitution, comprise:

10 mg/mL of colistin sulfate,

2 x 10⁶ lU/mL of nystatin, and

8 mg/mL of micronized tobramycin sulfate,

9.10-18.20 mg/mL of SyrSpend® sf pH 4, 2.86 mg/mL of citric acid monohydrate, and

2 mg/mL of potassium sorbate.

In some cases, the reduced SyrSpend® sf pH 4 product results in more consistent reconstitution and reduced thickening of the suspension after 3 days. A reduction of from 20 to 40% is desirable, most preferably a reduction is 30% is most desirable.

In one particularly preferred embodiment, the liquid suspension, on reconstitution comprises a reduced amount of SyrSpend® sf pH. For example, the liquid suspension may, on reconstitution, comprise:

10 mg/mL of colistin sulfate,

2 x 10⁶ lU/mL of nystatin, and

8 mg/mL of micronized tobramycin sulfate,

13.65 mg/mL of SyrSpend sf pH 4,

2.86 mg/mL of citric acid monohydrate, and

2 mg/mL of potassium sorbate.

On reconstitution, the pH of the liquid suspension ranges from pH 4 to pH 5.

Desirably, the liquid suspension is reconstituted from the dry powder in the bottle provided to ensure dosing accuracy.

In one embodiment, a preferred container is a 240 mL capacity bottle, for example, a plastic, amber coated bottle which may be graduated if desired. Preferred plastic is polyethylene terephthalate (PET).

Preferably, the liquid suspension is formulated to contain 20 x 10 mL doses with each 10 mL dose containing: 100 mg colistin sulfate, 80 mg, tobramycin (as sulfate) and 2 x 10⁷ IU nystatin.

The preferred suspension has a shelf life of up to 8 weeks when stored at 2-8°C. Advantageously, during use, the suspension can be stored in a temperature controlled room of less than 25°C for up to one week.

Oral Paste for SDD

A portion of the API blend of the invention described above consisting of the blend of three APIs can be used to make an oral paste for topical administration to the mouth and throat of the patient.

Thus, the invention provides an oral paste comprising a blend of micronized tobramycin as described herein, colistin and nystatin components.

A preferred paste has a viscosity in the range of from 40,000 to 200,000 mPa.s at 20 °C, most preferably about around 110,000 mPa.s at 20 °C.

Suitably, the paste is a GMP compliant product. Preferably, the paste is water free.

Desirably, the paste does not include preservative.

Suitably, the paste is packaged in a dispensing package, for example, a syringe.

Preferably, the dispensing package enables delivery of a metered dose to the mouth and throat of a patient.

Most preferably, the dispensing package is a single use dispensing package.

In one preferred embodiment, the invention provides a paste comprising:

15 to 25 mg/g of colistin sulfate,

2 x 10⁶ to 3 x 10⁶ 1 U/g of nystatin; and

15 to 27.5 mg/g of micronized tobramycin sulfate.

In one preferred embodiment, the invention provides a paste comprising:

19.4 to 22 mg/g of colistin sulfate,

2.37 x 10⁶ to 2.625 x 10⁶ 1 U/g of nystatin; and

18 to 24 mg/g of micronized tobramycin sulfate.

In one preferred embodiment, the invention provides a paste comprising:

20 mg/g of colistin sulfate,

2.5 x 10⁶ 1 U/g of nystatin; and

20 mg/g of micronized tobramycin sulfate.

Desirably, the APIs are homogeneously dispersed throughout the paste.

Suitably, the paste comprises one or more excipients in addition to the above mentioned APIs.

In a preferred embodiment, the paste further comprises at least one mineral oil.

In a preferred embodiment, the paste further comprises at least one thickener. Suitable thickeners comprise hypromellose, for example, methocel™ e4m premium.

In a preferred embodiment, the paste further comprises petrolatum white.

A particularly preferred paste comprises mineral oil, hypromellose (methocel™ e4m premium), and petrolatum white.

In one preferred embodiment, the invention provides a paste comprising:

20 mg/g of colistin sulfate,

2.5 x 10⁶ 1 U/g of nystatin;

20 mg/ml of micronized tobramycin sulfate;

50 mg/g mineral oil light;

177 mg/g hypromellose (methocel™ e4m premium), and

686 mg/g petrolatum white.

In one preferred embodiment, the invention provides a paste comprising, per 0.5g: 10 mg of colistin sulfate,

1.25 x 10⁶ III of nystatin;

10 mg of micronized tobramycin sulfate;

25 mg mineral oil light;

88.5 mg hypromellose (methocel™ e4m premium), and qs petrolatum white.

Desirably, the colistin sulfate meets BP specification.

Desirably, the nystatin meets Eur. Ph. specification.

Desirably, the tobramycin sulfate meets USP specification.

In preferred embodiments, the paste is provided in a metered dose container, such as a syringe, suitably an oral syringe.

Desirably, the metered dose container is configured for a single use, preferably a 1 mL syringe configured to deliver 0.5 g of the paste.

A preferred paste has a viscosity in the range of from 40,000 to 200,000 mPa.s.

Preferred paste has a shelf life of up to 6 months when stored at 2-8°C. Shelf life may be tested by PET and stability studies mentioned above. Advantageously, during use, the paste can be stored in a temperature controlled room of less than 25°C for up to one week and meet the stability requirements specified.

SDD Drug Kit

The invention provides a kit of parts comprising at least one container comprising a dry powder formulation as described herein for topical administration to a patient's stomach, together with a plurality of paste dispensing packages as described herein for topical administration of the paste to the mouth and throat of a patient.

In one preferred embodiment, a drug kit contains twenty 1 mL BD oral syringes of oral paste, a single container of dry powder for reconstitution, and a syringe filling adaptor.

One aspect of the invention relates to use of micronized tobramycin in the manufacture of a medicament for the prevention of hospital acquired respiratory infection and/or sepsis in a mechanically ventilated patient.

Another aspect of the invention relates to the use of a dry powder formulation as described herein in the manufacture of a medicament for prevention of hospital acquired respiratory infection and/or sepsis in a mechanically ventilated patient. Another aspect of the invention relates to a use of a paste as described herein in the manufacture of a medicament for prevention of hospital acquired respiratory infection and/or sepsis in a mechanically ventilated patient.

Therapeutic methods

Another aspect of the invention relates to a method of preventing a hospital acquired respiratory infection in a mechanically ventilated patient comprising one or more the following steps:

(i) topically administering to the patient's orogastric tract a therapeutically effective amount of a suspension reconstituted from a dry powder formulation of the invention;

(ii) topically administering to the patient's stomach a therapeutically effective amount of an oral paste according to the invention.

Preferably, the method comprises both steps (i) and (ii).

Suitably, the method further comprises the step of:

(iii) intravenous administration of antibiotics to the patient.

Colistin and tobramycin are antibiotics while nystatin is an antifungal. Tobramycin sulfate is an aminoglycoside antibiotic with good aqueous solubility. It is effective against many strains of Gramnegative bacteria, including Pseudomonas aeruginosa.

Nystatin is a non-absorbable polyene with wide antifungal activity, especially against Candida spp., including C. giabrata and C. krusei. Non-absorbable polyenes significantly reduce fungal carriage and overall fungal infections and are less likely to promote the emergence of resistant strains of Candida as opposed to other antifungal agents.

Colistin is a multicomponent antibiotic. It consists of a mixture of several closely related decapeptides (polymyxin E). As many as 13 components have been identified. The main components are polymyxin El and E2. Colistin has an antimicrobial spectrum and mode of action similar to that of polymyxin B, but is slightly less active. It has a bactericidal action on most Gram-negative bacteria.

These antibiotics are directed at eradicating the carriage of potentially pathogenic microorganisms including Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), aerobic Gram-negative bacilli and yeasts. The combination of colistin and tobramycin is synergistic against Proteus and Pseudomonas species. It is the most potent anti-pseudomonal combination associated with an effective clearance of Pseudomonas bacteria from the gut.

None of these actives are absorbable and they are only used in topical application to the mouth, throat and stomach of a patient. Only the use of non-absorbable antimicrobials can guarantee concentrations in the saliva and faeces high enough to selectively abolish the carriage of pathogenic micro-organisms without influencing the protective anaerobic flora, thereby decreasing colonisation resistance. Emergence of resistance to colistin is rare. Although there are bacteria producing tobramycin- inactivating enzymes, colistin is thought to protect tobramycin from being destroyed by these bacterial enzymes. Tobramycin is the preferred aminoglycoside because it is intrinsically most active against Pseudomonas and is minimally inactivated by saliva and faeces. It also has beneficial activity against Staphylococcus aureus. Both agents (colistin and tobramycin) absorb endotoxins released by aerobic Gram-negative bacilli in the gut. This feature is important because endotoxins can be absorbed from the gut of seriously ill patients and produce fever, release inflammatory mediators and cause shock. The use of intravenous antimicrobials that suppress the patient's indigenous flora in the digestive tract is associated with overgrowth of extended-spectrum beta-lactamase (ESBL)-producing aerobic Gram-negative bacilli in the gut. Enteral colistin and tobramycin prevent the overgrowth of aerobic Gram-negative bacilli. The combination of colistin and tobramycin administered via the oral and gastrointestinal route also prevents the persistence of ESBL producing aerobic Gram-negative bacilli.

Example 1 - SDD Administration Protocol

Every six hours, 0.5 g of the SDD paste (a pea-sized amount) was evenly applied to the buccal mucosa, oropharynx, while 10 mL of SDD suspension was administered to the gastrointestinal tract via a gastric/poly-pyloric tube.

Both the SDD paste and SDD suspension were administered in conjunction with a four-day course of an intravenous antibiotic if patients were not already receiving an intravenous antibiotic. The patients requiring the four-day course of intravenous antibiotics were prescribed cefotaxime 1 g six-hourly or ceftriaxone 1 g daily, with dose adjusted as appropriate for organ dysfunction. Ciprofloxacin (400mg 12-hourly) was used as an alternative if there was a contraindication to cephalosporins (e.g. allergy). Patients already receiving an intravenous antibiotic to treat infection continued the prescribed antibiotic for the usual duration of therapy.

Example 2 - Tobramycin HPLC Assay - SDD Oral Paste and SDD Suspension

Column: 150mm x 4.6 mm C18 column, particle size 3 microns, 12 nm (YMC-Pack Pro). HPLC Conditions: 1.2 mL/min flow rate. Stop time: 30 mins. Oven Temp: 40 C. Injection Vol. 20 microlitres. Detection: 365 nm (bandwidth 8 nm). Tobramycin retention time: about 15 mins.

Mobile phase: dissolve 2.0 g of tris(hydroxymethyl)aminomethane in 800 mL of water. Add 20 mL of IN sulfuric acid and 1180 mL of acetonitrile. Mix well. Pass through a filter of 0.22 pm of finer pore size.

Solution A: 10 mg/mL of 2,4-dinitroflurobenzene in ethanol anhydrous. This solution may be used for 5 days if refrigerated when not in use. Solution B: 15 mg/mL of tris(hydroxymethyl)aminomethane in water. This solution may be used for 1 month if refrigerated when not in use.

Solution C: 3 mg/ml of tris(hydroxymethyl)aminomethane prepared as follows.

Transfer 20 ml of Solution B to a 100 ml volumetric flask. Add dimethyl sulfoxide while mixing, add dimethyl sulfoxide to volume. Use this reagent within 4 hours. If kept immersed in an ice-water bath below 10C, the reagent may be used up to 8 hours.

Solution D: Chlorofom : Hexane (1:1)

PROCEDURE

Standard

Stock standard solution: Weigh accurately about 33 mg of tobramycin reference standard into a 50 mL volumetric flask. Add about 20 mL of water, 1 ml of 1 N sulfuric acid, and vortex to dissolve. Make up to volume with water (0.66 mg/mL Tobramycin).

Standard solution: Dilute 5 mL of the stock standard solution to 25 mL with water (0.132 mg/mL tobramycin)

Suspension: Shake for 1-2 minutes before weighing each aliquot. Immediately after shaking, accurately weigh about 0.75 g of the well mixed sample into a 50 mL polypropylene tube.

Paste: Accurately weigh about 0.35 g of a well-mixed sample into a 50 mL polypropylene tube.

Add 10 mL of Solution D and vortex for 5 minutes. *Add 15 m L of water and vortex at high speed for a further 10 minutes. Centrifuge at 4000 rpm for 5 minutes. Carefully transfer the upper water layer into a 50 mL volumetric flask.** Repeat two more times from * to **, and combine all the separated water layers into the same 50 mL volumetric flask. Add 1 mL of 1 N sulfuric acid, mix, and make up to volume with water. Filter about 10 mL of the sample solution with 0.45 pm nylon syringe filter. This is the Sample solution.

Derivatisation reaction (Standard solution, Sample solution and blank)

To separate 50 mL volumetric flasks transfer 5 ml of the standard solution, 5 mL of sample solution and 5 mL of water blank. To each flask add 10 mL solution A and 10 mL solution C, mix and insert the stopper. Place the flasks in a constant temperature bath at 60 ± 2 °C, and heat for 50 ± 5 min. Remove the flasks from the bath, and allow to stand further 10 min. Add acetonitrile to about 2 mL below the 50 mL mark. Allow to cool to room temperature, then dilute with acetonitrile to volume. Filter with 0.45 pm nylon syringe filter the derivatised standard, sample and blank solutions into amber HPLC vials.

Perform a single injection of the derivatized standard-1 to check the retention time and if the integration parameters are suitable. Adjust the integration parameters to achieve an appropriate integration of the peak is necessary and check if the resolution is within acceptance criteria.

Inject the derivatised standard-1 solution for 6 times.

Acceptance criteria:

%RSD for peak area of analyte should not be more than 2.0%

%RSD for the retention time of the peak for analyte should not be more than 1.0 %

Column plate number for analyte should be not less than 2000

Tailing Factor for analyte should be between 0.8 and 1.5

Capacity Factor (k¹) for analyte should be not less than 1.5

The resolution of any peaks to analyte peak should be > 1.4.

Inject the derivatised standard-2 solution twice.

The Similarity Factor between standard-1 and standard-2 should be between 0.98 and 1.02.

Similarity Factor = Peak area of standard(2'}x weight o f standard(l) Peak area of standard/!) x weight of standard(2)

Analysis

Inject derivatised blank solution. Inject derivatised sample-1 solution twice followed by 2 injections of derivatised blank solution. Inject derivatised sample-2 solution twice followed by 2 injections of derivatised blank solution. Inject derivatised standard-1 solution after every 8 - 10 injections and at the end of the run.

System precision

Acceptance Criteria:

%RSD for peak area for Tobramycin of all standard-1 is preferably not be more than 2.0% % RSD for the retention time of the peak for Tobramycin of all standards-1 should not be more than 1.0%.

CALCULATION

Suspension

Area spl x Std cc (mg/mL x 50 x std purity (g/g) x SG

Tobramycin (mg/mL)

Area std x spl weight (g)

Paste

Area spl x Std cc (mg/mL) x 50 x std purity (g/g)

Tobramycin (mg/g)

Area std x spl weight (g)

Where:

Spl: sample 1

Std: standard

SG: Specific gravity (g/mL)

The % RSD for all sample injections should be not more than 2%.

Example 3 - SDD Gastric Powder for Suspension Study on Thickening over Time

PURPOSE: The purpose of this study is to determine the effect of varied concentrations of SyrSpend® SF pH 4 on the thickness of the reconstituted SDD Gastric Powder for Suspension when stored at 2-8°C or 25°C.

Three different formulations were assessed in this study: Formulation A which is unchanged from original product having a concentration of 45.5 SyrSpend®; Formulation B which contains a 30% reduction in SyrSpend®; and Formulation C which contains a 50% reduction in SyrSpend®.

MATERIALS:

• 4 bottles potassium sorbate and citric acid (Batch No. 1808002)

• Distilled water

• 3 API premix (Batch No. 1807005)

• SyrSpend® SF pH 4 dry (IGN T170186)

• 2 bottles SDD Gastric Powder for Suspension (Batch No. 1804007)

• Incubator (set to 25°C)

• Refrigerator (2-8°C)

• 10 mL oral/enteral syringes

METHOD: Two bottles of powder for suspension of each formulation were made up as follows (6 in total)

One bottle of each formulation was stored at either 2-8°C (refrigerator) or 25°C (Incubator for a total of 5 days.

Two 10 mL doses were extracted in the morning and again in the afternoon of each day of the study to simulate the 10 mL qid dosing protocol of the SuDDICU study. These doses were dispensed into a white plastic weigh boat to observe any changes in consistency over the study period. All bottles were vigorously shaken and allowed to sit momentarily to allow the foaming to settle prior to drawing up the doses.

RESULTS: There was a marked difference in the consistency of the different preparations and across the different storage conditions in this study. It was noted that the suspension was considerably thicker in those samples stored at 25 °C, as opposed to those stored at 2-8 °C, this was especially apparent in the Formulation A samples (created with 100% of the original formulation of SyrSpend®). Figure 5 below demonstrates the changes in consistency over time and across the 2 storage conditions for the 6 samples tested. Both the 2-8 °C and 25 °C samples with 50% SyrSpend® seemed very watery. Figure 5 illustrate that the suspensions thickened over time and that storage at 25 °C resulted in a thicker suspension for all concentrations.

All doses were able to be extracted from all samples during this study, though care needed to be taken, particularly toward the end of the study not to draw up any air bubbles when extracting the dose. An increase in foaming was also observed in the Formulation C samples.

It was noted that there was an increase in separation of the suspension in the Formulation B and C but all samples were able to be easily re-suspended with shaking.

Separation of suspension: Overnight separation of suspension was observed in both Formulation B and Formulation C. In some cases, the suspension corresponding to Formulation A was too thick to remove from the bottle at the end of the 5-day course, Formulation A and B samples that were stored at 25 °C were cut open at the conclusion of the study to inspect the consistency and volume of residue remaining. The Formulation B sample was observed to have some product adhered to the wall of the bottle; this amount of product was not deemed to be excessive nor was it found to be excessively thick. The Formulation A sample was also found to have some residue adhered to the wall of the bottle but again, this did not seem unmanageably thick nor did it seem to be an excessive volume.

DISCUSSION: The formulation of the originally SDD Gastric Powder for Suspension contains 13.65 g SyrSpend® SF pH4 and is stored at the patient's bedside for the duration of the 5-day course of treatment. It has been reported that nursing staff administering the product to the patients were finding that the consistency is too thick and over the course of treatment becomes even thicker and impossible to draw up into the oral/enteral syringe and administer via a naso-gastric (NG) tube with instances of NG tube blockages reported also.

This study examined the effects of decreasing the concentration of SyrSpend® in the product and looked at the impact of storage at either 2-8 °C or 25 °C.

The Formulation C samples contained a 50% reduction in the amount of SyrSpend® when compared to formulation A (the currently available product). These samples were much easier to handle, however, they seemed very watery in consistency. Additionally, an increased level of foaming was observed in these products regardless of the storage condition.

Table 2 above outlines volumes of purified water to be added to each formulation based on the amount of SyrSpend® it contains. Formulation C had in excess of 200 mL purified water added in order to make up to 210 mL total volume, this exceeds the maximum recommended dilution of the suspending agent which is likely to have led to a breakdown of the active suspending technology from

Fagron®. There may be a risk of an irreversible sediment cake forming with this formulation, leading to less than expected doses of antibiotic being administered to the patient and ultimately, a lack of consistency in the trial data. This over-dilution of the suspending vehicle may also explain the observation of increased foaming in these samples as the anti-foaming agent in the vehicle may have been too dilute to have an effect. Additionally, previous studies have shown a trend toward an increasing pH with decreasing concentrations of SyrSpend® SF pH4, this was particularly apparent with the 50% concentration (equivalent to Formulation C in this study). It is important to maintain the pH of the product within a range of 4-5 in order for the preservative system to perform optimally.

The Formulation B samples were the easiest products to work with in this study, this is supported by previous studies at this concentration. Though an increase in foaming was observed, it was quick to settle. Some overnight separation was also observed in formulation B samples which was quickly able to be re-suspended. Previous studies indicate that the pH is acceptable in samples containing this concentration of SyrSpend®. Over the duration of this study, the consistency of the

Formulation B samples product increased in thickness, this was particularly apparent in the sample stored at 25 °C, however, even at the completion of the study, the sample stored at 2-8 °C was very easy to handle with all doses able to be easily extracted. It was noted that more care was required toward the end of the study to ensure that air was not drawn up into the syringe. This formulation would likely be easy to administer via a naso-gastric tube according to the usual protocol.

Formulation A is highly viscous, more noticeably so when stored at 25 °C. This formulation was made up according to the instructions provided to the investigation sites by adding 190 mL purified water and shaking vigorously. The consistency of this formulation in both storage conditions thickened over the course of the study. Before each dose was drawn up, the bottles were shaken vigorously, this allows the active suspending technology of the SyrSpend® to reduce viscosity. It was noted however, that it can be more difficult and take more time to successfully draw up a dose as care needs to be taken to avoid drawing up air which can happen when the plunger of the syringe is withdrawn too rapidly. The bottle that was stored at 25 °C was cut open at the conclusion of the study and it was demonstrated that the product was not unmanageably thick and minimal product remained with no lumps visible, indicating that the full dose had been extracted each time. This is in contrast to the reports received from some investigation sites, this may potentially be due to incorrect reconstitution or insufficiently vigorous or no shaking of the product prior to administration.

CONCLUSION AND FURTHER STUDIES: While the current formulation seemed satisfactory in this study, it is understood that some sites are having difficulty using this product. As such, an alternative formulation is to be considered. Formulation C would not be a suitable alternative. Formulation B which contains a 30% reduction in SyrSpend® seems the most appropriate option if the currently available product is not satisfactory. It maintains an appropriate pH, is diluted within the range specified by the manufacturer of SyrSpend® and is easy to manage even when stored at 25 °C.

Example 4 - Paediatric Nasogastric Tube Study

As explained above, the liquid suspension tends to thicken slightly on storage and in some cases may block narrow tubes such as used in the paediatric patient population. Therefore, a paediatric liquid suspension was prepared that is formulated to have a reduced viscosity compared to the original formulation. A study was carried out to investigate the likelihood of tube blocking using the paediatric liquid suspension.

A first paediatric liquid suspension was tested daily over the course of 6 days while being stored at <25 °C. A second paediatric liquid suspension was tested daily over the course of 6 days while being stored in the fridge at 2 °C to 8 °C.

It is observed that suspension stored at <25 °C tends to become viscous over time compared to the suspension stored at 2 °C to 8 °C. In fact, the viscosity of the suspension stored at 2 °C to 8 °C over the 6 days tested it was evidence there would be no possibility of tube blockage.

Nasogastric tubes sizes ranging from 6Fr to lOFr were tested with 5 mL or lOmL volumes. None of the suspensions were found to stick to, much less, block any of the tubes tested.

Embodiments

The following Embodiments are disclosed herein:

Embodiment 1. A method of manufacturing a dry powder pharmaceutical API combination formulation for orogastric topical application comprising the step of: blending micronized tobramycin having a top cut d(98) of about 100 microns or less, with one or more additional active pharmaceutical ingredients.

Embodiment 2. The method of Embodiment 1, wherein the micronized tobramycin is dry blended with additional active pharmaceutical ingredients including colistin and nystatin.

Embodiment 3. The method of Embodiment 1 or Embodiment 2, wherein the manufacture is GMP manufacturing.

Embodiment 4. The method of any one of the preceding Embodiments, wherein the micronized tobramycin has d(98) of about 75 microns or less as determined by laser diffraction particle size distribution analysis.

Embodiment 5. The method of any one of the preceding Embodiments, wherein the micronized tobramycin has d(98) of about 40 to about 60 microns as determined by laser diffraction particle size distribution analysis. Embodiment 6. The method of any one of the preceding Embodiments, wherein the method further comprises the step of: blending one or more preservatives into the dry powder pharmaceutical API combination formulation.

Embodiment 7. The method of Embodiment 6, wherein the preservative is a combination of an alkali sorbate and an acid.

Embodiment 8. The method of Embodiment 6 or Embodiment 7, wherein the preservative is potassium sorbate and citric acid.

Embodiment 9. Dry powder pharmaceutical API combination formulation obtainable by the method of any one of the preceding embodiments.

Embodiment 10. A dry powder pharmaceutical API combination formulation comprising micronized tobramycin having a top cut d(98) of about 100 microns or less, colistin and nystatin.

Embodiment 11. The formulation of Embodiment 10, wherein the micronized tobramycin has a d(98) of about 75 microns or less as determined by laser diffraction particle size distribution analysis.

Embodiment 12. The formulation of Embodiment 10 or Embodiment 11, wherein the micronized tobramycin has d(98) of about 40 to about 60 microns as determined by laser diffraction particle size distribution analysis.

Embodiment 13. The formulation of any one of Embodiments 10 to 12, wherein micronized tobramycin has d(98) of about 50 microns as determined by laser diffraction particle size distribution analysis.

Embodiment 14. The formulation of any one of Embodiments 10 to 13, wherein the tobramycin has a uniform particle shape, for example, a substantially uniformly spherical particle shape.

Embodiment 15. The formulation according to any one of Embodiments 10 to 14, wherein the tobramycin is provided as tobramycin sulfate, preferably tobramycin sulfate BP grade or tobramycin sulfate USP grade.

Embodiment 16. The formulation according to any one of Embodiments 10 to 15, wherein the colistin is provided as colistin sulfate, colistin sulfate BP grade or colistin sulfate USP grade.

Embodiment 17. The formulation according to any one of Embodiments 10 to 16, further comprising a suspending agent, for example a modified starch such as SyrSpend Alka or SyrSpend sf, preferably SyrSpend sf buffered to pH 4.

Embodiment 18. The formulation according to any one of Embodiments 10 to 17, further comprising at least one preservative, for example, potassium sorbate.

Embodiment 19. The formulation according to any one of Embodiments 10 to 18, further comprising citric acid. Embodiment 20. A dry powder formulation according to any one of Embodiments 10 to 19, which is formulated for reconstitution as a liquid suspension, for example, reconstituted with purified or distilled water.

Embodiment 21. A dry powder formulation according to Embodiment 20, provided in a container, preferably a container comprising polyethylene terephthalate, for reconstitution with a liquid, for example purified or distilled water.

Embodiment 22. A dry powder formulation according to Embodiment 21, wherein the container comprises a with a syringe filling adaptor, preferably adapted a child resistant screw cap. Embodiment 23. A liquid suspension reconstituted from the dry powder formulation of any one of Embodiments 10 to 22, preferably reconstituted with water, such as purified or distilled water.

Embodiment 24. A liquid suspension according to Embodiment 23, reconstituted to comprise 10 mg/ml of colistin sulfate, 2 x 10⁶ lU/mg of nystatin and 8 mg/ml of micronized tobramycin sulfate. Embodiment 25. A liquid suspension according to embodiment 23 or 24, further comprising SyrSpend sf pH 4.

Embodiment 26. A liquid suspension according to any one of Embodiments 23 to 25, further comprising potassium sorbate.

Embodiment 27. A liquid suspension according to any one of Embodiments 23 to 26, further comprising citric acid.

Embodiment 28. A liquid suspension according to any one of Embodiments 23 to 27, comprising 45.5 mg/ml or 22.75 mg/ml of SyrSpend sf pH 4, 2.86 mg/ml of citric acid monohydrate, and 2 mg/ml of potassium sorbate.

Embodiment 29. A liquid suspension according to any one of Embodiments 23 to 28, wherein the liquid formation is stable at 2-8 °C for up to 8 weeks.

Embodiment 30. A liquid suspension according to any one of Embodiments 23 to 29, wherein the liquid formation is stable at or below 25 °C for up to 1 week.

Embodiment 31. A paste manufactured from a blend of the dry powder formulation according to any one of Embodiments 1 to 22.

Embodiment 32. A paste comprising a blend of micronized tobramycin, colistin and nystatin components.

Embodiment 33. A paste according to Embodiment 32, further comprising mineral oil, a thickener preferably hypromellose, for example, methocel e4m premium; and petrolatum white. Embodiment 34. A paste according to Embodiment 32 or embodiment 33, further comprising mineral oil, hypromellose (methocel e4m premium), and petrolatum white. Embodiment 35. The paste of any one of Embodiments 31 to 34, further comprising flavouring and/or taste masking agents, for example, such as cyclodextrin, sugar, dextrose, or magnasweet.

Embodiment 36. A paste according to Embodiment 31 or Embodiment 35, comprising 20 mg/g of colistin sulfate, 0.2 mu/g of nystatin and 20mg/ml of tobramycin sulfate, 50 mg/g mineral oil, 177 mg/g hypromellose (methocel e4m premium), and 686 mg/g petrolatum white.

Embodiment 37. A paste according to any one of Embodiments 31 to 36, provided in a metered dose container, such as a syringe.

Embodiment 38. A paste according to Embodiment 37, wherein the metered dose container is configured for a single use, preferably, the container is a 1 ml syringe, filled to deliver 0.5g of the paste.

Embodiment 39. A kit comprising at least container of a dry powder formulation according to any one of Embodiments 1 to 22 and a paste according to any one of embodiments 31 to 38.

Embodiment 40. A kit according to Embodiment 39, comprising a plurality of single use dosing units of paste.

Embodiment 41. A kit according to Embodiment 39 or embodiment 40, further comprising instructions for use.

Embodiment 42. Use of micronized tobramycin having a top cut d(98) of about 100 microns or less as a component in a dry powder combination formulation for topical application, particularly orogastric topical application.

Embodiment 43. Use of micronized tobramycin having a top cut d(98) of about 100 microns or less as a component in a dry powder API combination formulation for reconstitution to a liquid suspension.

Embodiment 44. Use of micronized tobramycin of about 100 microns or less in the manufacture of a medicament for the prevention of hospital acquired infection and/or sepsis in ventilated patients.

Embodiment 45. Use of a dry powder formulation according to any one of Embodiments 1 to 22 in the manufacture of a medicament for the prevention of hospital acquired infection and/or sepsis in ventilated patients.

Embodiment 46. A method of preventing a hospital acquired infection and/or sepsis in ventilated patients comprising the steps of topical administering to the respiratory tract of a subject in needed thereof, a therapeutically effective amount of one or more of a reconstituted dry powder formulation according to any one of Embodiments 1 to 22 and a paste according to any one of Embodiments 31 to 38.

Claims

Claims

1. A method of manufacturing a dry powder pharmaceutical API combination formulation for orogastric topical application comprising the step of: blending micronized tobramycin having a top cut d(98) of about 100 microns or less, with one or more additional active pharmaceutical ingredients.

2. The method of claim 1, wherein the micronized tobramycin is dry blended with additional active pharmaceutical ingredients including colistin and nystatin.

3. The method of claim 1 or claim 2, wherein the micronized tobramycin has d(98) of about 75 microns or less as determined by laser diffraction particle size distribution analysis, such as of about 40 to about 60 microns as determined by laser diffraction particle size distribution analysis.

4. The method of any one of the preceding claims, wherein the method further comprises the step of: blending one or more preservatives into the dry powder pharmaceutical API combination formulation.

5. The method of claim 4, wherein the preservative is a combination of an alkali sorbate and an acid, such as potassium sorbate and citric acid.

6. A dry powder pharmaceutical API combination formulation obtainable by the method of any one of the preceding claims.

7. A dry powder pharmaceutical API combination formulation comprising: micronized tobramycin having a top cut d(98) of about 100 microns or less; colistin; and nystatin.

8. The formulation of claim 7, wherein the micronized tobramycin has a d(98) of about 75 microns or less as determined by laser diffraction particle size distribution analysis, such as of about 40 to about 60 microns as determined by laser diffraction particle size distribution analysis.

9. The formulation of claim 7 or claim 8, wherein the tobramycin has a uniform particle shape, for example, a substantially uniformly spherical particle shape.

10. The formulation according to any one of claims 7 to 9, wherein: the tobramycin is provided as tobramycin sulfate, preferably tobramycin sulfate BP grade or tobramycin sulfate USP grade; and/or the colistin is provided as colistin sulfate, colistin sulfate BP grade, or colistin sulfate USP grade.

11. The formulation according to any one of claims 7 to 10, further comprising any one or more of: a suspending agent, for example, a modified food starch; at least one preservative, for example, an alkali sorbate; or a food acid, for example, citric acid.

12. The formulation according to any one of claims 7 to 11, which is formulated for reconstitution as a liquid suspension, for example, reconstitution with purified or distilled water.

13. The formulation according to claim 12, provided in a container, preferably a container comprising a syringe filling adaptor, for reconstitution with a liquid.

14. A liquid suspension reconstituted from the formulation of any one of claims 7 to 13, preferably reconstituted with water, such as purified or distilled water.

15. The liquid suspension according to claim 14, reconstituted to comprise 10 mg/mL of colistin sulfate, 2 x 10⁶ lU/mg of nystatin and 8 mg/mL of micronized tobramycin sulfate, optionally further comprising: a suspending agent, a preservative, or a food acid, or a combination of any two or more of these.

16. The liquid suspension according to claim 15, wherein the liquid formation is stable at 2-8 °C for up to 8 weeks, or stable at or below 25 °C for up to 1 week.

17. A paste manufactured from a blend of the formulation according to any one of claims 1 to 13.

18. A paste comprising a blend of micronized tobramycin, colistin and nystatin components, optionally further comprising: mineral oil; a thickener, preferably hypromellose; and petrolatum white.

19. The paste according to claim 17 or claim 18, provided in a metered dose container, such as a syringe, optionally wherein the syringe is configured for a single use.

20. A kit comprising at least container of a dry powder formulation according to any one of claims 1 to 13 and a paste according to any one of claims 17 to 19.

21. Use of micronized tobramycin having a top cut d(98) of about 100 microns or less as a component in a dry powder combination formulation for topical application, particularly orogastric topical application, or for reconstitution to a liquid suspension.

22. Use of a dry powder formulation according to any one of claims 1 to 13 in the manufacture of a medicament for the prevention of hospital acquired infection and/or sepsis in ventilated patients.

23. A method of preventing a hospital acquired infection and/or sepsis in ventilated patients comprising the steps of topical administering to the respiratory tract of a subject in needed thereof, a therapeutically effective amount of one or more of a reconstituted dry powder formulation according to any one of claims 1 to 13 and a paste according to any one of claims 17 to 19.