AU2021104379A4

AU2021104379A4 - Sustained Release Hydrogel Formulation Containing Levofloxacin Hemihydrate for Ocular Drug Delivery

Info

Publication number: AU2021104379A4
Application number: AU2021104379A
Authority: AU
Inventors: Mithun Bhowmick; Pratibha Bhowmick; Adrija Bhunia; Ajit Joshi; Shubhrajit Mantry; Dipansu Sahu
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-07-21
Filing date: 2021-07-21
Publication date: 2022-05-19
Anticipated expiration: 2029-07-21

Abstract

: A major problem in ocular therapeutics is the attainment of an optimal drug concentration at the site of action. To achieve effective ophthalmic therapy, an adequate amount of active ingredient must be delivered and maintained within the eye. The most frequently used dosage forms i.e., eye solution, eye ointments, eye gels and eye suspensions are compromised in their effectiveness by several limitations leading to poor ocular bioavailability' Ophthalmic use of viscosity enhancing agents, penetration enhancers, cyclodextrins, prodrug approaches, and ocular inserts and the ready existing drug carrier systems. The purpose of this research was to develop a Stimuli sensitive mainly temperature sensitive ophthalmic drug delivery system of Levofloxacin hemihydrate, a Fluoroquinolone antibiotic. Poloxamer 407 as thermo responsive gelling agent, PEG 6000 or PEG 400 as viscolyzer and Carbopol 940 or PVA as mucoadhesive agent were employed for the formation of temperature sensitive hydrogels. The promising temperature sensitive formulations Fl, F2 and F3 were evaluated for pH, drug content, in vitro gelation, in vitro viscosity of liquid formulation, in vitro drug release, in-vitro viscosity of gelled formulations, sterility, Pyrogen testing, ocular irritation, and stability. Percent drug content of 97.25%, 98.1% and 98.35%; viscosity of 32.523Pa-s, 34.448 Pa-s, and 38.234 Pa-s at 10 rpm and cumulative percent release of 85.52%, 81.11% and 74.72 % was observed formulations F1, F2 and F3 respectively. The developed formulations were therapeutically efficacious, stable, and non-irritant and provided sustained release of the drug over a period of 8 hour.

Description

Title of Invention Sustained Release Hydrogel Formulation Containing Levofloxacin Hemihydrate for Ocular Drug Delivery

Background of Invention Eye is the most simply reachable site for topical administration of a medication. Drugs are commonly applied to the ocular system for a localized action on the surface or in the interior of the eye. The ocular system is most interesting organ due to its drug disposition characteristics. For illness of the eye, topical ocular drug delivery can be easily appreciated because the drug enters the systemic circulation circumventing the hepatic first pass effect. The preceding summary demonstrated that the formulator faces many constraints and prerequisites when developing a modified-release topical ophthalmic drug. In addition to the traditional requirements of oral drugs for safety, efficacy, and stability, ophthalmic products must exhibit additional properties. The regulatory demands for new ophthalmic chemical entities are, most of the time, outweighed by the development efforts and costs compared to the size of the ophthalmic market. Ophthalmic therapy can be improved by increasing the comeal residence time of drugs. The existing ocular drug delivery systems are thus fair and inefficient. The design of ocular system is undergoing gradual transition from an empirical to rational basis; Interest in the broad areas of ocular drug delivery has increased in recent years due to an increased understanding of a number of ocular physiological process and pathological conditions. Hydrogels are polymeric networks that absorb large quantities of water while remaining insoluble in aqueous solutions due to chemical or physical crosslinking of individual polymer chains. They resemble natural living tissue more than any other class of synthetic biomaterials due to their high-water content; furthermore, the high-water content of the materials contributes to their biocompatibility. Hydrogels show minimal tendency to adsorb proteins from body fluids because of their low interfacial tension. Further, the ability of molecules of different sizes to diffuse into (drug loading) and out of (drug release) hydrogels allow the possible use of dry or swollen polymeric networks as drug delivery systems for oral, nasal, buccal, rectal, vaginal, ocular and parenteral routes of administration. Among Hydrogels the phase-change polymers, which may trigger drug release in response to external stimuli, are the most investigated. Hydrogels providing such 'sensor' properties are referred as "Stimuli Sensitive Hydrogels" or smart hydrogels. "Smart" hydrogels, or Stimuli sensitive hydrogels, are very different from inert hydrogels in that they can "sense" changes in environmental properties such as pH and temperature and respond by increasing or decreasing their degree of swelling. The volume-changing behavior of 'smart' hydrogels is particularly useful in drug delivery applications as drug release can be triggered upon environmental changes. These "intelligent" or "smart" polymers play important role in drug delivery since they may dictate not only where a drug is delivered, but also when and with which interval it is released. The stimuli that induce various responses of the hydrogels systems include physical (temperature) or chemical (pH, ions) stimuli.

Summary: In the present research we aimed our investigation to prepare and evaluate the Stimuli Sensitive (temperature Sensitive) hydrogels of an antibacterial ophthalmic drug Levofloxacin hemihydrate, belonging to a specific category Fluoroquinolones of 3rd generation which have a broad spectrum antibiotic activity, with efficacy against various gram-positive and gram-negative microorganisms, in view of increasing precomeal residence time & bioavailability of drug. "Levofloxacin" is a widely used drug for treatment of acute conjunctivitis. However, use of Levofloxacin in Ophthalmic formulations is limited due to its pH dependent solubility. The drug shows minimum solubility at the pH above 6.2 and to be given by ophthalmic route it must have pH b/w 6.5 to 7.4. Therefore, eye drops of Levofloxacin generally suffer the drawbacks of either poor bioavailability or frequent administration.

To increase the solubility of Levofloxacin at the pH above 6.2, the Temperature Sensitive ophthalmic hydrogels of the drug were formulated along with p-Cyclodextrin; which increased its solubility to a considerable extent. For the preparation of Temperature Sensitive Hydrogels were prepared using Poloxamer 407 as thermosensitive gelling agent along with PEG 6000 or PEG 400 as viscolyzers and PVA or Carbopol as mucoadhesive agents. Formulations were evaluated for different parameters like pH, appearance, drug content, in vitro gelation studies, in vitro viscosity studies of liquid formulations, in vitro release studies, in vitro viscosity studies of gelled formulations, sterility test, Pyrogen testing, ocular irritation and stability studies. The appearance and clarity of all the prepared formulations was found satisfactory. The pH of all formulations was also found to be satisfactory in the range of 6 - 7.4. In vitro gelation studies and In vitro viscosity studies of liquid formulations concluded that all the formulations showed optimum Gelling capacity and Viscosity. These formulations were then subjected to further evaluation parameters. All Temperature Sensitive Ophthalmic Hydrogels formulation showed sustained drug release for a period of 8 hour. Formulation F1 and F2 showed maximum percent drug release. By the Drug release Kinetics studies, it was observed that all the Temperature Sensitive ophthalmic Hydrogels formulation followed zero order release but 'n' value b/w 0.5 to 0.89, suggesting Non Fickian transport mechanism. Results of sterility test and Pyrogen test confirmed that all the selected formulations were sterile and Pyrogen free. From the stability studies it was confirmed that Stimuli Sensitive ophthalmic formulations of Levofloxacin hemihydrate remained more stable at ambient temperature (25°C) and humidity. The maximum instability of Stimuli Sensitive formulations was observed at 60°C and 4°C (significant decrease in drug content).

Working (Method of preparation): Hydrogels were prepared by using Levofloxacin hemihydrate (0.512% w/v) along with some formulation additives to attain the desirable qualities of the ophthalmic dosage forms. The inactive ingredients included in the sol-gel systems to perform different functions such as the p Cyclodextrin (solubility enhancer), Benzalkonium chloride (preservative), sodium chloride (tonicity contributors), Hydroxy propyl methyl cellulose or Polyethylene Glycol (Viscolyzer) and Polyvinyl Alcohol or Carbopol 940 (mucoadhesive) etc. The required amount of Carbopol 940 was dispersed in Phosphate buffer pH 5.5 with continuous stirring until completely dissolved. Then the required amount of HPMC (+3000 cps) was allowed to hydrate with buffer solution for about 24 hours, to minimize the formation of lumps. After 24 hours both the polymer solutions were mixed together with gentle stirring. Levofloxacin was dissolved in small volume of buffer solution. -cyclodextrin, Benzalkonium chloride and sodium chloride were added to drug solution. This drug solution was added to the polymeric mixture and required volume was made up with 5.5 pH phosphate buffer. The pH of formulation was adjusted using sodium hydroxide (2M). Finally, the resultant solution was subjected to membrane filtration by using cellulose membrane. Prepared formulation was then sterilized by autoclaving for 30 minutes at 1200 C temperature and 15 psi pressure.

Preparation of Temperature Sensitive Hydrogels: Various Combinations of Poloxamer 407, Polyethylene glycol 6000, Polyethylene glycol 400, Polyvinyl Alcohol and Carbopol 940 in different concentrations were prepared and evaluated by visually assessing the gelling capacity and viscosity in order to identify the compositions suitable for use as in Temperature Sensitive systems.

Evaluation: Drug Content Temperature Sensitive formulations were then subjected for determination of drug content. The drug content was determined by diluting 1 ml of the formulation to 100 ml with STF pH 7.4. Aliquot of 1 ml was withdrawn and further diluted to 10 ml with STF. Levofloxacin hemihydrate concentration was then determined at 287 nm by using UV spectrophotometer. Test was performed in triplicate and average of two readings was taken as true Drug content. Viscosity Studies of Liquid Formulations All Temperature Sensitive liquid formulations were evaluated for Viscosity. Viscosity was measured using a Brookfield viscometer (DV-II + Pro) in the small volume adapter. The viscosity of liquid formulations measured at 10 rpm was used for purposes of comparative evaluation of prepared Temperature Sensitive Hydrogels. In vitro Release Studies

The in vitro release of Levofloxacin hemihydrate from all Temperature Sensitive formulations was studied through cellophane membrane using a USP-I dissolution testing apparatus (Model 912). The dissolution medium used was Simulated Tear Fluid freshly prepared (pH 7.4). A 2-ml volume of the gelled formulation was accurately kept in Cellophane membrane, previously soaked overnight in the dissolution medium to form a cellophane pouch. Cellophane membrane pouch having drug was put in the cylindrical basket. The cylindrical basket was attached to the metallic driveshaft and suspended in 900 ml of dissolution medium maintained at 37± 2C. The dissolution medium was stirred at 50 rpm. Aliquots, each of 5-ml volume, were withdrawn at regular intervals and replaced by an equal volume of the dissolution medium. The aliquots were diluted with the dissolution medium and analyzed by UV spectrophotometer at 287 nm.

Viscosity Studies of Gelled Formulations Viscosity of instilled formulation is an important factor in determining residence time of drug in the eye. It was noted from various literature that the formulations before gelling should have a viscosity of 5 to 1000 mpa and after gelling in the eye will have a viscosity from about 50 ,000 mpa. The prepared solutions were allowed to gel in the simulated tear fluid and then the viscosity determination was carried out by using Brooke field viscometer (DV-II + Pro) at angular velocity 10 rpm.

Sterility Testing An ophthalmic preparation should be sterile therefore the test for sterility is very important evaluation parameter. Liquid Nutrient broth media containing Peptone (10gm), Meat extract (10gm), Sodium chloride (0.50gm) and Distilled water 1000 ml was prepared. pH of media was adjusted to 7.2 0.2 and it was autoclaved at 125C for 30 minutes. Direct inoculation method was used. 2 ml of liquid from test container was removed with a sterile pipette or with a sterile syringe or a needle. The test liquid was aseptically transferred to Liquid Nutrient broth media (200 ml). The liquid was mixed with the media. The inoculated media were incubated for 15 days at 37°C temperature and 75% relative humidity. Pyrogen Testing An ophthalmic formulation must be Pyrogen free. After sterilization the end products or metabolic products of bacteria might be left in formulation, which may act as Pyrogen. Hence

Pyrogen testing is also necessary in ophthalmic formulations. One formulation is selected and subjected to Qualitative Fever Response Test in rabbits. Pyrogen testing was performed according to IP. Three rabbits weighing 2.25 kg were selected for the purpose. Formulation in a dose of l0ml/kg of body weight was injected in the ear vein of rabbit and injection was completed within 10 seconds. Rectal temperature after giving the formulation was recorded at 1, 2 and 3 hr. and Rise in temperature was determined.

Claims

Claims: 1. Herein we claim a sustained release hydrogel formulation containing levofloxacin hemihydrate for ocular drug delivery.
2. The Formulation claimed in 1 has decreased frequency of drug administration as lower dose is required.
3. The formulation claimed in 1 showed increased ocular residence time.
4. The developed formulation has a sustained release action without the need for surgical implantation.
5. The formulation claimed in 1 has improved bioavailability at the sight of action.
6. We also claim method of preparation of sustained release hydrogel formulation containing levofloxacin hemihydrate for ocular drug delivery,

List of figures: 21 Jul 2021

Fig. 1: FTIR spectra of Levofloxacin hemihydrate Fig. 2: FTIR spectra of Physical Mixture Fig. 3: Percentage cumulative drug release of formulation List of tables: Table 1: Formulation design for Temperature Sensitive Hydrogels 2021104379

Table 2: Optimization of Temperature Sensitive Hydrogels Table 3: Rheological Study of Temperature Sensitive Hydrogels Table 4: Percentage cumulative drug release of formulation Table 5: Pyrogen testing of Formulation

Fig.1: IR Spectra of Levofloxacin hemihydrate

Fig.2: IR Spectra of Physical Mixture

90.00 80.00 70.00 60.00 50.00 40.00 30.00 F1 F2 F3

20.00 10.00 0.00 0 1 2 3 4 5 6 7 8 9 Time (Hrs.)

Fig. 3: Percentage cumulative drug release of formulation

Table 1: Formulation design for Temperature Sensitive Hydrogels

Quantity (% w/w) Contents F1 F2 F3 Drug 0.500 0.500 0.500 Poloxamer 407 20 20 20 Poly ethylene glycol 6000 1 8 6 2021104379

Poly ethylene glycol 400 6 8 10 Poly vinyl alcohol 0.5 0.5 0.5 Carbopol 940 0.4 0.5 0.6 β-CD 0.2 0.2 0.2 Benzalkonium chloride 0.1 0.1 0.1 Sodium chloride 0.9 0.9 0.9 Phosphate buffer pH 7.4 QS QS QS 100 gm 100 gm 100 gm

Table 2: Optimization of Temperature Sensitive Hydrogels

S.NO. Composition of Formulation Resulted formulation (% W/V) F1 Poloxamer 407 (20%) PVA (0.5%), Formulation is good with good gelling capacity PEG 6000 (1%) and optimum viscosity. F2 Poloxamer 407(20%), PVA (0.5%), Formulation is liquid but Gelling capacity is PEG 400 (10%) low. Formed gel dissolves rapidly. F3 Poloxamer 407(20%), PVA (0.5%), Formulation is moderately viscous and Gelling PEG 400 (10%) capacity is optimum.

Table 3: Rheological Study of Temperature Sensitive Hydrogels

Temperature Sensitive Formulations Viscosity of Gelled Formulations at 10 rpm (Pa-S) F1 37.487

F2 38.925 F3 41.112

Table 4: Percentage cumulative drug release of formulation

Time (Hrs) F1 F2 F3 0.5 11.34 14.86 14.35 2021104379

1.5 19.36 19.45 20.35 2 28.64 32.22 29.51 2.5 36.64 38.11 38.73 3 48.11 44.21 42.18 3.5 55.34 49.32 48.91 4 62.45 56.61 53.46 4.5 66.43 61.66 58.99 5 69.11 65.54 63.44 5.5 72.86 68.72 65.36 6.5 80.94 76.33 69.13 7 83.44 79.86 71.77 7.5 84.11 80.53 73.46 8 85.52 81.11 74.72

Table 5: Pyrogen testing of Formulation

Formulations Sr. No. Rise in Temperature (0C) Average rise in of rabbit Temperature After 1hr After 2hr After 3hr F2 Rabbit-1 0.3 0.1 0.4 0.4 Rabbit-2 0.2 0.3 0.4 0.45 Rabbit-3 0.3 0.2 0.2 0.35