WO2018154538A1

WO2018154538A1 - Method for encapsulating tetracyclines

Info

Publication number: WO2018154538A1
Application number: PCT/IB2018/051227
Authority: WO
Inventors: Vanessa GALLEGO LONDOÑO; Julián LONDOÑO; Santiago MONSALVE BURITICÁ; Andrés Felipe LONDOÑO BARBARÁN
Original assignee: Corporacion Universitaria Lasallista; Gentech Biosciences S.A.S
Priority date: 2017-02-27
Filing date: 2018-02-27
Publication date: 2018-08-30
Also published as: CO2017001953A1

Abstract

The invention relates to a method for encapsulating antibiotics of the tetracycline group, comprising the following steps: separately preparing solutions of gelatine, saccharose and tetracyclines; and mixing the saccharose solution with the tetracycline solution, the mixture obtained then being added to the gelatine solution to form a suspension characterised by a total solids percentage of between 20 and 40% and a particle size of between 0.33 and 0.44µm. Finally, the suspension obtained is dried by the spray drying method until an oral powder formulation is obtained. The method is characterised by yields of between 40 and 60% and an encapsulation efficiency of between 35 and 60%.

Description

TETRACICLINE ENCAPSULATION METHOD

Field of the Invention

The present invention is in the field of chemistry, specifically in relation to encapsulation methods of antibiotics of the tetracycline group for the control of bacterial infections.

Description of the state of the art

Tetracyclines constitute a group of antibiotics, some natural and others obtained by semisynthesis, which cover a broad spectrum in their antimicrobial activity. Despite their great antimicrobial properties, they have gastrolesive effects that are characterized by the production of nausea and vomiting when administered orally. There are some commercial presentations in the form of a tablet that offer an enteric coating, however to administer doses in concentrations other than the composition of the tablet, the tablet must be divided to meet the required dose, which alters the cover and enteric protection of the drug. An alternative that could counteract its irritating effects in its passage through the gastric route is encapsulation, since it allows modifying biopharmaceutical characteristics of the drug, such as its release profile. In this way, two important aspects of its administration could be modified: the dosage frequency and the quantities required. Finally, this will affect the reduction of some of the gastrointestinal adverse effects described above.

US20090004281A1 describes a pharmaceutical composition and its method of preparation and administration. The composition includes a core containing at least one drug (eg doxycycline, insulin) in combination with at least one pharmaceutically acceptable excipient. The composition further includes an osmotic sub-coating surrounding the core (eg sodium chloride, sucrose, mannitol), and a release coating, together with adjuvants and binders (eg starch, pre-gelatinized starch, gelatin). The manufacturing process consists of preparing individual solutions of the drug and of the osmotic subcoats, which are mixed until a homogeneous solution is fed to a spray dryer. US20130196954A1 discloses a method for preparing a sustained-release doxycycline tablet. The tablet comprises doxycycline (0.1-99.0%) together with binders between (5-10%), excipients and adjuvants (25-50%). Doxycycline or other chemically modified tetracycline may be included in the tablet and also contains appropriate inactive ingredients, which are well known in the art, and may include bulking agents such as microcrystalline cellulose, calcium sulfate, starches, disintegrating agents, microcrystalline cellulose, gelatin and sweeteners.

On the other hand, document US8415331B2 discloses a solid dosage form of a doxycycline metal complex and a process for manufacturing a doxycycline metal complex in solid dosage form. The solid dosage further includes pharmaceutically known excipients. The process comprises the steps of: (i) providing an aqueous solution of doxycycline or a physiologically acceptable salt thereof; (ii) mixing a metal salt with the aqueous solution; (iii) mixing a base to increase the pH of the aqueous solution, thereby forming a metal doxycycline suspension; and (iv) drying the suspension, thereby forming a dry granulation of the doxycycline metal complex.

Although tetracycline encapsulation processes are disclosed in the state of the art, it is necessary to develop new methods of encapsulating antibiotics of the tetracycline group in different presentations and dosages, which optimize the pharmacological action and reduce the incidence or intensity of Gastrointestinal lesions when administered orally and that also allow a comfortable administration that favors the maintenance of the pharmaceutical regimen.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a method of microencapsulating antibiotics of the tetracycline group, comprising: separately preparing a solution of gelatin, sucrose, and tetracyclines (eg tetracycline, minocycline, tigylcycline, chlortetracycline, doxycycline, oxytetracycline, demethyl ); mix the sucrose solution with the tetracycline solution; subsequently the obtained mixture is added to the gelatin solution until a homogeneous mixture is formed, characterized by a percentage of total solids between 20 and 40% and a particle size between 0.33 and 0.44μπι; finally the mix Homogeneous is dried by the spray drying method, until an oral powder formulation of encapsulated doxycycline is obtained. The method is characterized by performance percentages between 40 and 60% and encapsulation efficiency between 35 and 60%.

Brief description of the figures

FIG. L Response surface and estimated equation for: A) Size; B) Viscosity

FIG. 2 Release of microencapsulated doxycycline at pH between 1.0 and 3.0 and pH between 6.8 and 7.4: (Tta A). Formulation without carboxymethyl cellulose; (Tto B) Formulation with carboxymethyl cellulose.

FIG. 3 Scanning electron microscopy (SEM) of the microparticles obtained by spray drying: (A) Formulation with gelatin and sucrose; (B) Formulation with gelatin, sucrose and carboxymethyl cellulose.

Detailed description of the invention

Encapsulation is defined as a packaging technology for solid, liquid or gaseous materials. The sealed capsules can release their contents at controlled speeds under specific conditions, and can protect the encapsulated product from light, oxygen and pH, among others. The encapsulation consists of the formation of particles formed by a porous membrane containing an active substance. The material or mixtures of materials to be encapsulated is thus covered or trapped within another material or system. The materials used for encapsulation can be gelatin, fats, oils, gum arabic, calcium alginate, waxes, wheat starch, corn starch, rice starch, potato starch, nylon, cyclodextrin, maltodextrin, sodium caseinate, sucrose and carboxymethyl cellulose.

Encapsulation in the area of medications allows modifying the release profile of an active substance. One of the groups of drugs susceptible to encapsulation treatments due to their gastrolesive effects are tetracyclines. Tetracyclines are broad spectrum antimicrobials, some natural and others obtained by semisynthesis, are characterized by their activity against a large group of gram-positive and gram-negative bacteria, aerobic and anaerobic and atypical microorganisms such as Chlamydia sp, Rickettsia sp, Mycoplasma sp, Borrelia sp, Treponema pallidum, Helicobacter pylori, Plasmodium sp and some mycobacteria. Tetracyclines belong to a group of antibiotics with a basic tetracyclic chemical structure and common biological activity, formed by the fusion of four benzene rings with various substituents; Its chemical structure gives them an amphoteric character that allows the formation of salts, both with acids and with bases, usually using soluble hydrochlorides.

The present invention proposes a method of encapsulation of tetracyclines, for example selected from the group: minocycline, tigylcycline, chlortetracycline, doxycycline, oxytetracycline and demethylchlortetracycline, to obtain an oral powder composition that facilitates its dosing and reduces the gastrolesive effects produced by the irritant capacity of this.

According to the method of the invention, a gelatin solution, a sucrose solution and a tetracycline solution are individually prepared; optionally a carboxymethyl cellulose solution can be added. Subsequently, the tetracycline solution and the sucrose solution are mixed until a dispersion is formed, to which the gelatin solution is added to form a suspension characterized by a percentage of total solids between 20 and 40%, preferably between 30 and 40% and a particle size between 0.30 and 0.48 μπι, preferably 0.35 and 0.40. The suspension is dried until a powder composition of encapsulated tetracyclines is obtained. More specifically, initially each component of the formulation is individually dispersed in an aqueous medium. The quantity of the component to be dispersed should be such that its percentage in total solids quantity is: for gelatin between 10 and 40% w / w, preferably between 20 and 30%; for sucrose between 60 and 90% w / w, preferably 70 and 80%; and for tetracyclines between 5 and 15% w / w, preferably 8 and 10%. Additionally, the suspension may contain sodium carboxymethyl cellulose between 0.2 and 1% w / w, preferably between 0.3 and 0.8% of the total solids. In one embodiment of the invention, the tetracycline used is preferably doxycycline.

The tetracycline solution is mixed with the sucrose solution to form a dispersion, to which the gelatin solution is added to form the suspension. The suspension obtained is homogenized between 2000 and 6000 rpm for 10 cycles of one minute each to guarantee the total incorporation of the components and is characterized by the properties of Table 1.

Table 1. Features stable suspension of tetracyclines

Finally, the suspension is subjected to a mechanical encapsulation method such as spraying, atomization, lyophilization, fluidized bed drying and extrusion. In one embodiment, spray drying is used at an inlet temperature between 100 and 180 ° C, preferably between 120 and 140 ° C, an outlet temperature between 54 and 90 ° C, preferably between 60 and 80 ° C and a percentage of suction between 65 and 85%, preferably between 75 and 80%. The encapsulation method of the present invention has a percentage of encapsulation efficiency between 35 and 60%, preferably between 40 and 50% and yields between 40 and 60%, preferably 50 and 58%.

The encapsulation method of the invention provides a powder composition with a tetracycline content (e.g. doxycycline) between 2 and 10 mg per 100 mg of powder and is characterized by the properties of Table 2.

Table 2. Powder composition stability characteristics

The final powder composition has a release percentage at pH between 1.0 and 3.0 of 0.10 and 0.40% w / w encapsulated tetracycline / initial tetracycline (2-10% w / w), and at pH between 6.8 and 7.4 of 0.10 and 0.20% w / w encapsulated tetracycline / initial tetracycline (2-10% w / w).

The following Examples illustrate the invention, without the inventive concept being restricted thereto.

EXAMPLES

Example 1: Optimization of suspension conditions:

To obtain a stable suspension that allows optimum performance during the spray drying process, a composite central design (DCC) was applied for the optimization of the preparation conditions, in which the parameters of percentage of total solids were evaluated (ST) between 20 to 40% and the homogenization speed between 2000 to 6000 rpm. 4 replicas were applied to the center within the design, that is, it was evaluated at 30% ST and 4000 rpm 4 times. The response variables evaluated were viscosity (μ), particle size and zeta potential (Q. The design was carried out with 6 degrees of freedom and randomized order and in total 12 treatments were analyzed. Table 3. YEAR variable VA response (second order model): A) Zeta potential; B) Size; C) Viscosity

A) Zeta potential

C) Viscosity

The ANOVA for each of the response variables, allows to identify that the zeta potential is not statistically affected in the studied ranges of the factors or by the interactions between them, since no data showed a P-value less than 0.05. Therefore, this variable was not taken into account for the optimization by response surface. For the size it is observed that at a higher percentage of solids and low homogenization rate, the particle size is larger (FIG. 1 A). As for viscosity, as the homogenization rate and the percentage of solids increase, this response is increasing in value (FIG. IB), it may be that increasing the contact area increases the interactions between the encapsulating agents and the system becomes more viscous; with the exception of treatment at 2000 rpm and 40% ST, where that speed is so low that it is not able to homogenize the system and therefore its viscosity value is so high. From the optimization carried out, it was established that the suspension should contain total solids between 20 and 40% to ensure greater efficiency, performance and stability during the drying process. The optimal conditions of the suspension from the DCC were (ST: 33.3% and 6000 rpm) for a μ: 256.0 cp, ζ: 18.74 mV and size: 0.44 μπι. These reached values are within the ranges required for spray drying.

Finally, for the inclusion of the sodium carboxymethylcellulose (CMC) component, a design of D-optimal mixtures was carried out with quadratic arrangement and with the following restrictions: gelatin (9.5 - 34.5% w / w), sucrose (65 - 90% w / w) and sodium carboxymethylcellulose (0.1-0.5% w / w). The response variables taken into account in the design of mixtures were the same as the DCC (viscosity, zeta potential and size).

The ideal proportions of the encapsulants, according to the design, correspond to: 13.64% w / w gelatin, 85.86% sucrose and 0.5% w / w sodium carboxymethylcellulose. The values of the response variables obtained with the optimal mixture, μ: 325.5 cp, ζ: 21.30 mV and size: 0.33 μπι, indicate that the suspension has characteristics that provide stability and are suitable for improving technological parameters (efficiency and performance) during the spray drying process. Example 2: Prepare stable suspension with doxycycline

Total 50gr of suspension were prepared, independently dispersing each of the components in an aqueous medium: 38.25 g of sucrose were added to 18.0 mL of water; 6.08 g of gelatin was dispersed in 45.5 mL of water; 0.22 gr of sodium carboxymethyl cellulose was dispersed in 23.0 mL of water; and 4.95 g of doxycycline were dispersed in 14 mL of water. Each component was suspended in distilled water at 60 ° C and homogenized with magnetic stirring at 2000 rpm.

The suspension for spray drying was prepared by slowly adding 14 mL of the doxycycline solution to 18 mL of the sucrose solution, with constant mechanical stirring and at a temperature of 60 ° C. To guarantee the complete dispersion of the components, the mixture obtained was homogenized with an Ultraturrax at a speed of 6000 rpm for 1 minute. Subsequently, 23.0 mL of the carboxymethyl cellulose solution and 45.5 mL of the gelatin solution were added to the previously formed mixture of doxycycline and sucrose, maintaining mechanical stirring and temperature at 60 ° C. The suspension obtained was homogenized with an Ultraturrax at 6000 rpm for 10 cycles of one minute each. The final suspension obtained is characterized by the parameters in Table 4.

Table 4. Parameters stable suspension with doxycycline

Example 3: Doxycycline encapsulation Doxycycline encapsulation was performed by spray drying technique. For this, the suspension described in Example 2 was dried through a Spray Dryer under the following conditions: feed rate between 2 and 5 mL / min, inlet temperature between 100 and 180 ° C, an outlet temperature between 54 and 90 ° C and a percentage of aspiration between 65 and 85%.

Finally, an encapsulated doxycycline powder is obtained with a percentage of encapsulation efficiency between 35 and 60%, yields between 40 and 60%, encapsulated doxycycline content of 4.86 mg per 100 mg of powder and total doxycycline of 9.46 mg per 100 mg of powder. The doxycycline powder obtained is characterized by the parameters in Table 5.

Table 5. Stability parameters doxycycline powder composition

Example 4: Release tests at different pH values

To determine the percentage of doxycycline released at different pH values, 40mg of the powder composition obtained according to Example 3 was dispersed in 5ml of a 0.1N HCL solution and pH 1.2 with mechanical stirring of 50 rpm for two hours. at 37 ° C, the percentage of release obtained was 0.35% w / w of doxycycline released by the initial amount of doxycycline in the powder (2-10% w / w). The same analysis was performed but this time using a phosphate buffer solution at pH 7.4, the percentage of release obtained was 0.18% w / w% of doxycycline released by the initial amount of doxycycline in the powder (2- 10% w / w).

FIG. 2 corresponds to the percentage of doxycycline released at pH between 1.0 and 3.0 and pH between 6.8 and 7.4 for a formulation without sodium carboxymethylcellulose (Tto A) and with sodium carboxymethylcellulose (Tto B). The characterization of microparticles obtained from Spray drying was performed by scanning electron microscopy (SEM). As seen in FIG. 3, the inclusion of sodium carboxymethylcellulose as an encapsulating agent softens the surface of the particles and gives them the property of having a spherical shape, on the other hand the particles where only gelatin and sucrose were used as encapsulating agents, have forms irregular, cracks and pores. These characteristics are related to the release profile, being greater for the gelatin and sucrose particles at pH between 1.0 and 3.0, than with those that have in their carboxymethyl cellulose formulation, therefore this encapsulating agent grants greater protection at pH low.

Claims

1) A tetracycline encapsulation method comprising the following steps: a) preparing a gelatin solution;

b) prepare a sucrose solution:

c) preparing a solution of an antibiotic of the tetracycline type;

d) mixing the tetracycline antibiotic solution and the sucrose solution; e) add the gelatin solution to the mixture obtained in step (d) and form a homogeneous mixture characterized by a percentage of total solids between 20 and 40% and a particle size between 0.33 and 0.44μπι;

f) Dry the homogeneous mixture from step (e).

2) The process according to Claim 1, wherein the amount of each component must be such that its percentage in the amount of total solids is: for gelatin between 10 and 40% w / w, for sucrose between 60 and 90% w / py for tetracyclines between 5 and 15% w / w.

3) The process according to Claim 1, wherein the tetracycline is preferably doxycycline. 4) The process according to Claim 1, wherein the mixture of step (e) additionally contains carboxymethyl cellulose between 0.2 and 1% w / w total solids.

5) The process according to Claim 1, wherein the mixing of step (e) is carried out with stirring between 2000 and 6000 rpm for 10 cycles of one minute each.

6) The process according to Claim 1, wherein the drying method of step (f) is preferably spray dried, with an outlet temperature between 54 and 90 ° C at an inlet temperature between 100 and 180 ° C, a percentage of suction between 65 and 85%.

7) The process according to Claim 1, with a percentage of encapsulation efficiency between 35 and 60% and yields between 40 and 60%.

8) An encapsulated doxycycline powder composition obtained according to the process of Claim 1 to 7.

9) An encapsulated doxycycline powder composition according to Claim 8, with a doxycycline content between 2 and 10 mg per 100 mg of powder.

10) A doxycycline powder composition according to Claim 8, characterized by a particle size between 0.30 and 0.80 μπι and a z potential between 19.00 and 23.00 mV. 11) A doxycycline powder composition according to Claim 8, with a percentage of release at pH between 1.0 and 3.0 of 0.10 and 0.40 p / p and a percentage of release and at pH between 6.8 and 7.4 of 0.10 and 0.20 w / w encapsulated doxycycline / initial doxycycline.