WO2011125075A2

WO2011125075A2 - A novel gastroretentive delivery of macrolide

Info

Publication number: WO2011125075A2
Application number: PCT/IN2011/000241
Authority: WO
Inventors: Nandan Mohan Chandavarkar; Kour Chand Jindal; Rajkumar Malayandi
Original assignee: Fdc Limited
Priority date: 2010-04-08
Filing date: 2011-04-07
Publication date: 2011-10-13
Also published as: WO2011125075A3

Abstract

Disclosed herein is a novel gastroretentive delivery system of macrolide consisting of a hydrophilic swellable floating matrix system either alone or in combination with a bioadhesive system, which comprises super-disintegrants together with hydrophilic polymers and in-situ gelling agents to improve the gastroretention of dosage forms.

Description

"A NOVEL GASTRORETENTIVE DELIVERY OF MACROLIDE" Field of the invention:

The present invention relates to a novel gastroretentive delivery system of macrolide, comprising a hydrophilic swellable floating matrix system either alone or in combination with a bioadhesive system.

Background of the invention:

Macrolides are a class of broad-spectrum antibiotics that are used to treat a wide range of bacterial infections. Macrolides are derived from Streptomyces species. They have a common macrolytic lactone ring, to which one or more sugars such as cladinose and desosamine are attached. They are different from one another in their chemical substitutions on structures of various carbon atoms in the amino and neutral sugars. The lactone rings are usually 14, 15 or 16-membered. Currently available macrolides in common use are erythromycin and the newer agents clarithromycin and azithromycin. These new macrolides are semisynthetic derivatives of erythromycin, with structural modifications to improve tissue penetration and broaden the spectrum of activity.

The mechanism of action of the macrolides involves inhibition of bacterial protein synthesis by binding reversibly to the subunit 50S of the bacterial ribosome, thereby inhibiting translocation of peptidyl-tRNA during translation (the production of proteins under the direction of DNA). Although the cells of humans also have ribosomes, these eukaryotic cellular protein factories differ in size and structure from the ribosomes of prokaryotes.

Macrolides tend to accumulate within leukocytes, and are therefore actually transported into the site of infection. Thus, macrolides bind to the large ribosomal subunit in the vicinity of the peptidyl transferase center and cause cell growth arrest due to inhibition of protein synthesis. This action is mainly bacteriostatic, meaning that bacterial growth and reproduction are inhibited, in contrast to bactericidal antibiotics which directly kill bacteria. Macrolides can be bactericidal in high concentrations. Macrolide antibiotics are used in the treatment of infections such as respiratory tract, genital, gastrointestinal and soft tissue infections. Macrolides have activity against many gram-positive bacteria (excluding enterococci and methicillin-resistant Staphylococcus aureus), respiratory gram-negative pathogens, Mycobacterium avium infections and gonorrhea. Macrolide antibiotics are noted for their intracellular accumulation and activity against intracellular pathogens such as Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella spp. Apart from antimicrobial activities, macrolides can modify host cell functions. Clarithromycin and azithromycin have similar spectrum to erythromycin but increased activity against Hemophilus, Mycobacterium avium intracellulare and toxoplasma. Azithromycin has increased gram-negative activity, while clarithromycin has increased gram-positive activity, against Methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae (only penicillin-susceptible Streptococcus pneumoniae (PSSP)), Viridans Streptococci, Bacillus and Corynebacterium. Newer macrolides (clarithromycin and azithromycin) have enhanced activity (azithromycin>clarithromycin>erythromycin) against gram-negative aerobes (H. influenzae, M. catarrhalis, Neisseria sp.). All macrolides have excellent activity against a typical bacteria including Legionella pneumophila - Dissolved Organic Carbon (DOC), Chlamydia sp., Mycoplasma sp and Ureaplasma urealyticum.

Oral administration of drugs, in conventional form, is perhaps the least predictable route of drug administration, however it is the most preferable route of administration as far as the patient compliance is concerned. Some aspects of unpredictability include wide range of highly variable conditions such as pH, agitation intensity and composition of the gastrointestinal fluids as a dosage form passing down the gastrointestinal tract (GIT). One particular aspect of unpredictability is in controlling the site of absorption throughout the tract. Certain therapeutic agents are only absorbed by specific part of the GIT, such as in the stomach or proximal GIT.

The absorption of therapeutic agents in the GIT is dictated by the drug release location in the GIT as well as by the gastrointestinal contents. Some agents are more efficiently absorbed from upper part of the GIT while others are absorbed from lower parts of the GIT. Therefore, in instances where the drug is not absorbed uniformly over the length of the GIT, the rate of absorption may not be constant in spite of the drug delivery system delivering the agent at a constant rate into the gastrointestinal fluids.

Gastroretentive drug delivery is an approach to prolong gastric residence time of the drug, thereby targeting site-specific drug release in the upper gastrointestinal tract for local or systemic therapies. Gastroretentive dosage forms can remain in the gastric region for long period of time, and hence significantly prolong the gastric retention time of drugs. Prolonged gastric retention improves bioavailability, reduces drug waste, and improves the solubility of drugs that are less soluble in a high pH environment. It has applications also for local drug delivery to the stomach and proximal small intestines.

There are several literatures describing the technologies concerned with gastroretentive drug delivery system and their therapeutic applications in last two decades. Several gastroretentive drug delivery system being designed and developed, including high density (sinking) system that is retained in the bottom of the stomach, low density (floating) system that causes buoyancy in gastric fluid, mucoadhesive system that causes bioadhesion to stomach mucosa, and unfoldable, extendible or swellable systems which limits emptying of the dosage forms through the pyloric sphincter.

Oral medications are generally administered as immediate release dosage forms. The major disadvantage of such immediate release preparations is the high frequency of drug administration and fluctuations in drug plasma levels. Use of an oral controlled release preparation circumvents these problems.

Controlled floating drug delivery systems are designed to deliver a therapeutic agent in such a way that the dosage form is released within a particular therapeutic window so that effective and safe blood levels are maintained for a period as long as the system continues to deliver the drug at a particular rate. Such controlled delivery usually results in substantially constant blood levels of the therapeutic agent as compared to fluctuations observed with immediate release dosage forms. Controlled delivery may also result in optimum therapy, reduce the frequency of dosing, and may also reduce the severity of side effects. Gastric emptying of dosage forms is an extremely variable process, and ability to prolong and control the emptying time is a valuable asset for dosage forms, which reside in the stomach for a longer period of time than conventional dosage forms. Several difficulties are faced in designing controlled release systems for better absorption and enhanced bioavailability. One of such difficulties is the inability to confine the dosage form in the desired area of the gastrointestinal tract. Drug absorption from the gastrointestinal tract is a complex process, and is subject to many physiological and drug variables. It is widely acknowledged that the extent of gastrointestinal tract drug absorption is related to contact time with the small intestinal mucosa. In last two decades, large amount of research has been carried in designing and development of gastroretentive dosage forms. However, very few products are entered into clinical development and subsequently entered into the market. Due to variability in gastrointestinal physiology and associated unpredictable gastric emptying, many systems show poor in vitro and in vivo correlation. Hence, there is a need for developing a gastroretentive system for the delivery of macrolide, which ensures the gastric retention as well as clinical benefit.

Int. J. Pharm., 270, 1-8 (2004) describes the comparative oral pharmacokinetics of immediate-release (IR) and control led-release (CR) dosage forms of azithromycin. The purpose of the study is to the prove risk associated with high peak plasma drug concentration after oral administration of IR dosage form and subsequent toxicity associated with peak plasma drug concentration. Controlled release formulation shows elimination of pronounced peak as well as fluctuations, which reduces or minimizes azithromycin adverse effects associated with IR products.

Am. J. Oto., 31, 1 (2009) discusses the efficacy of extended release azithromycin with amoxicillin/clavulanate. Three hundred and seventy eight patients are randomized for single dose extended release azithromycin and three hundred and seventy one for amoxicillin/clavulanate. More patients randomized to azithromycin extended-release, experienced resolution of symptoms at day 5 than those randomized to amoxicillin/clavulanate.

AAPS Pharm SciTech., 9 (1), 231-237 (2008) discloses the hydrodynamically balanced delivery system for Clarithromycin in the treatment of Helicobacter pylori mediated peptic ulcer, which, after oral administration should have the ability to prolong gastric resistance time with the desired in vitro release profile for the localized action in the stomach. However, the article describes the method of treatment for H. Pylori infection only and is not directed to treat other systemic infections.

J. Control. Rel., 125, 33-41 (2008) discloses floating in-situ gelling system of clarithromycin, which was prepared using gellan gum as gelling polymer, and calcium carbonate as floating agent, for potentially treating gastric ulcers associated with Helicobacter pylori. The article explains the treatment strategy for local infection and systemic therapies.

US 6068859 discloses a controlled release dosage form of azithromycin, process for preparing the dosage form, and method of treating a microbial infection. The enteric coated dosage form can also operate by releasing the bulk of azithromycin contained therein in the portion of GIT distal to the duodenum. The oral dosage form is designed for sustained or delayed drug release. The said formulation in the patent, describes the controlled and/or delayed release formulation.

The above said formulation describes the release of drug in intestine, where the drug gets poor solubility and dissolution; hence it may lead to poor and incomplete absorption of the drug from the dosage form.

US 6984403 discloses an oral dosage form having an effective amount of an alkalizing agent and an azithromycin multiparticulate, wherein said multiparticulate comprises azithromycin, a mixture of glyceryl mono-, di- and tri behenates and a poloxamer. The proposed formulation in the patent describes the bioavailability enhancement using alkaline substance. However, azithromycin being a high dose drug, require longer period of time for dissolution in alkaline conditions, and hence offers incomplete absorption. Moreover, if the drug gets absorbed from stomach, it may cause adverse drug reactions due to peak plasma drug concentration.

WO 001 5198 discloses a pharmaceutical composition in the form of tablets or capsules which provides a combination of spatial and temporal control of drug delivery comprising an active ingredient or drug, a gas generating component, a swelling agent, a viscolyzing agent and optionally a gelling polymer. The application describes the composition, which comprises of viscolyzers such as xanthan gum and guar gum as one of the component. Moreover, carbonates and other acid salts are used as a gas generating system in the said application.

Orally administered immediate-release formulations of macrolide are absorbed rapidly, and pharmacokinetically exhibit a two-compartment model. Macrolide therapy with immediate release formulations is associated with various adverse effects such as nausea, vomiting, abdominal cramping, headache and dizziness. Conventional immediate-release formulations have a more-pronounced incidence of adverse effects as result of higher peak plasma concentrations of macrolide. Controlled release formulations of macrolides reported in literatures, consist of delayed release formulation and/or sustained release formulation. Macrolides being a high dose drug with pH dependent solubility along with gastric instability creates critical issues in formulation development. High dose of drug, associated with poor solubility in higher pH lead to incomplete absorption, whereas lower pH offers gastric instability.

None of the systems in aforementioned prior art has attempted to stabilize the macrolides in presence of acidic pH, where the drug gets better dissolution and absorption by designing gastroretentive formulation. Thus the present invention discloses pharmaceutical formulations having approach to eliminate the peak plasma concentration of macrolide by developing a stable floating controlled-release drug delivery system. The controlled-release drug delivery system releases macrolide at a predetermined rate, eliminating the undesired peak plasma concentration, and reducing or eliminating unwanted side effects and resulting in a better dosage regimen. Hence, there is an urgent need to develop the gastroretentive formulation of macrolide consisting of a hydrophilic swellable floating matrix system either alone or in combination with a bioadhesive system, which releases the macrolides at a predetermined rate, while ameliorating the drawbacks of existing prior art. Object of the invention:

The principal object of the present invention is to design a novel gastroretentive drug delivery system for administration of macrolide antibiotics, which releases said macrolides at a predetermined rate and eliminates the undesired peak plasma drug concentration.

Another object of the present invention is to provide gastroretentive drug delivery system for administration of macrolide antibiotics, with reduced side effects and better safety and clinical efficacy by maintaining the plasma drug concentration within the therapeutic window.

Yet another object of the present invention is to provide gastroretentive dosage form for administration of macrolide antibiotics, which releases the macrolide in upper part of GIT, and hence enhances the bioavailability of dosage forms by using different technologies such as hydrophilic swellable floating matrix system and bioadhesive system.

Further object of the present invention is to improve the stability of macrolides in presence of acidic environment of stomach.

Summary of the invention:

The present invention discloses a novel gastroretentive delivery system of macrolide comprising a hydrophilic swellable floating matrix system either alone or in combination with a bioadhesive system, which involves the use of super-disintegrants with hydrophilic polymers and in-situ gelling agents, which can improve the gastroretention of dosage forms. Further, the controlled release gastroretentive dosage form of the present invention offers enhanced stability of the macrolides in gastric fluid by incorporating an alkali in the matrix system, which not only stabilizes the drug in acidic pH but also controls the drug release by reducing its solubility in stomach by offering alkaline micro- environmental pH. The invention further provides controlled mode of drug release and minimal fluctuation in plasma drug concentration. Detailed description of the invention:

The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.

The present invention provides a novel gastroretentive delivery system of macrolide, comprising a hydrophilic swellable floating matrix system either alone or in combination with a bioadhesive system.

The phrase "hydrophilic swellable floating matrix system" as used herein consists of polymers like hydrophilic polymers, natural gums and their derivatives. These polymers swell in the presence of dissolution media and form thick gel on the surface of the dosage form. The swelling of the dosage forms reduce the density of the dosage form and hence favor for floating of the dosage form on the dissolution media. Moreover, thick gel on the surface of the hydrophilic matrix, retard the drug release by increasing the diffusion layer thickness. The release profile of the dosage form is based on the concentration of hydrophilic polymer and other excipients. The controlled release profile from the hydrophilic swellable floating systems, provide constant drug level in blood and prevents dose dumping of the dosage form.

The phrase "bioadhesive system" as used herein is designed to retain the drug and/or dosage form in the specific part of the body in order to provide the prolonged effect. Bioadhesive polymers have strong affinity with gastric mucosa and hence provide prolonged gastroretention, which favors for drug absorption.

The oral delivery of macrolide antibiotics for systemic effect has been considered as a challenging task for a formulation scientist. Macrolide antibiotics exhibit high dose and pH dependent solubility along with poor permeability, poor biopharmaceutical properties and bioavailability. This class of antibiotics shows better solubility at acidic pH, than at neutral pH and alkaline pH. Optimization of biopharmaceutical properties and hence improvement of bioavailability by proper formulation designing, is the prerequisite for delivery of macrolides. Macrolides due to their high dose, require longer gastric residence time for complete absorption. Moreover at acidic pH, the macrolides degrade in the stomach and hence offer poor absorption and bioavailability. In contrast to that, intestinal pH offers good stability of macrolide antibiotics, but the rate limiting step for intestinal delivery is poor solubility in intestinal pH. High dose of macrolides along with poor solubility in intestine, offers poor and incomplete absorption of the drug in distal part of GIT. It is therefore an urgent need to develop an ideal system for oral delivery of macrolide antibiotics. The present invention is found effective to deliver the macrolide antibiotics by gastroretentive dosage form.

Accordingly, the instant invention provides gastroretentive delivery system of macrolide consisting of a hydrophilic swellable floating matrix system either alone or in combination with a bioadhesive system comprising:

a) macrolide in an amount of 10% to 98% w/w;

b) hydrophilic polymers in an amount of 0.1% to 30% w/w;

c) in-situ gelling agents in an amount of 0.5% to 25% w/w and

d) superdisintegrants in an amount of 0.1% to 20% w/w of the total formulation.

The macrolides are class of antibiotics characterized by their large lactone ring structures and by their growth-inhibiting (bacteriostatic) effects on bacteria. The macrolide used in the formulations of this invention, are selected from a group consisting of erythromycin, azithromycin, clarithromycin, roxithromycin, dirithromycin spiramycin, josamycin, midecamycin, telithromycin and troleandamycin preferably azithromycin and clarithromycin, ranging from 10% to 98% w/w.

In a preferred embodiment, the present invention describes use of superdisintegrants with hydrophilic polymers as rate controlling polymer, and in-situ gelling agents, which can improve the gastroretention of dosage forms.

The unique combination of superdisintegrants, hydrophilic polymer and in-situ gelling agent, offers different mechanisms such as floating , bioadhesion and swellable matrix to ensure the gastric retention of dosage form for desired period of time. Superdisintegrants are used in the formulation to increase the swellability of the dosage form, and offer increased size of dosage form that is not affected by gastric emptying. In addition, superdisintegrants increase the wettability of dosage forms which allow penetration of gastric fluid inside the dosage form. The intimate contact of gastric fluid with hydrophilic polymer, increases the gel strength of the matrix, and hence offers controlled mode of drug release from the dosage forms.

Superdisintegrants are used because of their high absorption properties. The formulation containing superdisintegrants swell in presence of gastric fluid, and hence create high pressure within the tablet matrix, which favors for faster disintegration of tablets. However, the role of superdisintegrants according to the present invention is to absorb high quantity of gastric fluids and hence offer aqueous environment for the matrix system. Gastric fluid is absorbed by superdisintegrants that leads to gellation of hydrophillic polymer and form a viscous gel layer. The formed gel layer maintains the integrity of the tablet dosage form and acts as a barrier for drug release.

Moreover, use of superdisintegrants in tablet dosage form, increases the floating time and reduces the floating lag time by offering low density and high matrix integrity. Hence superdisintegrants along with hydrophillic polymer and in-situ gelling agent, offer ideal gastroretention drug delivery system that would provide better drug release in stomach. Superdisintegrants used in the present invention include but are not restricted to crospovidone, croscarmellose sodium and sodium starch glycollate, ranging from 0.1% to 20% w/w of the total formulation.

Hydrophillic polymers are a network of polymeric chains that are water-insoluble, sometimes found as a colloidal gel wherein water is the dispersion medium. Hydrophillic polymers are highly absorbent i.e. they can contain over 99% water, and are derived from natural or synthetic polymers. Hydrophillic polymers also possess a degree of flexibility very similar to natural tissue, due to their significant water content. These polymers are used in the present invention not only to provide the stable matrix system, but also to act as a barrier for drug release. Hydrophillic polymers used in the present invention are selected from a group consisting of cellulose, cellulose derivatives, cellulose esters, natural gums, polyvinylpyrrolidone, polyvinyl alcohol and poly(ethylene oxide), ranging from 0.1 % to 30% w/w of the total formulation.

Moreover, in-situ gelling agents in the formulation offer not only rigidity to the matrix, which prevents dose dumping, but also provides controlled mode of drug release in addition to hydrophilic gelling polymer. In general, in-situ gellation takes place by one or more combinations of mechanism such as thermal gellation, ionic gellation, pH induced gellation. The present invention involves the in-situ gelling agent selected from the categories of pH induced gellation and/or ionic gellation.

In-situ gelling agents are selected from a group consisting of gellan gum, sodium alginate, locust bean gum and other natural gums, cellulose esters, modified cellulose esters, acrylate, methacrylates copolymers, and co-block polymers of acrylates and acrylic acid derivatives preferably gellan gum and sodium alginate, ranging from 0.5% to 25% w/w of the total formulation.

Ionic agents are used to induce the gellation by exchange of ions preferably cations with the in-situ gelling agents. The ionic agents are selected from a group consisting of calcium chloride, calcium sulfate, calcium carbonate, calcium stearate, magnesium chloride, magnesium sulfate, magnesium carbonate, magnesium stearate, zinc chloride and zinc carbonate preferably calcium carbonate, calcium chloride and calcium stearate.

In an another embodiment, the proposed controlled release gastroretentive dosage form, offers enhanced stability Of the macrolides in gastric fluid by incorporating alkali as stabilizer in the matrix system. The alkali present in the matrix system not only stabilizes the drug in acidic pH, but also controls the drug release by reducing its solubility in stomach by offering alkaline micro-environmental pH.

Stabilizers/alkali are used to improve the stability of macrolides antibiotics in presence of acidic gastric fluid. The stabilizer alters the microenvironment pH, and hence offer controlled mode of drug release from tablet matrix. Carbonates and bicarbonates are used to generate the carbon dioxide in the presence of gastric fluid, and hence reduces the density of dosage form, which favors reduction in floating lag time and increase in the floating time.

The stabilizers used in the formulations are selected from a group consisting of carbonates, phosphates and borates preferably carbonates and bicarbonates more preferably sodium carbonate, sodium bicarbonate, magnesium carbonate, calcium carbonate, aluminium carbonate and zinc carbonate, ranging from 0.5% to 15% of the total formulation.

The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.

Examples:

Example 1:

Azithromycin dihydrate, Methocel K 100 M, sodium alginate, sodium bicarbonate and crospovidone are individually weighed and sieved through # 40 mesh and blended together for 15 minutes followed by blending the same with talc. The final blend is lubricated with calcium stearate and compressed into the tablets. Dissolution profile

Example 2:

Azithromycin dihydrate, hydroxyethylcellulose, sodium alginate, calcium carbonate and crospovidone are individually weighed and sieved through # 40 mesh and the mixture is granulated with water for 10 minutes. The obtained wet mass is sieved through # 8 mesh and dried. The resulting dried granules are passed through # 30 mesh. Talc is added to the dried granules and the final blend is lubricated with calcium stearate and compressed into tablets.

Dissolution profile

Time (Hr) % drug release

1 8

2 16

4 32 6 53

8 72

12 96

Example 3:

Azithromycin dihydrate, Polyox N 60 K, sodium alginate and sodium starch glycollate are individually weighed and sieved through # 40 mesh and the mixture is then granulated with water for 10 minutes. The obtained wet mass is sieved through # 8 mesh and dried. The resulting dried granules are passed through # 30 mesh. Calcium carbonate and talc are added to the dried granules and the final blend is lubricated with calcium stearate and compressed into tablets.

Dissolution profile

Time (Hr) % drug release

1 18

2 28

4 43

6 56

8 67

12 84 Example 4

Azithromycin dihydrate, Methocel K 100 M, Sodium alginate, Microcrystalline cellulose, Crospovidone and Calcium sulfate dihydrate are individually weighed and sieved through # 40 mesh and the mixture is granulated with water for 10 minutes. The obtained wet mass is sieved through # 8 mesh and dried. The resulting dried granules are passed through # 30 mesh. Sodium bicarbonate and precipitated colloidal silicon dioxide are added to the dried granules and the final blend is lubricated with magnesium stearate and compressed into tablets.

Dissolution profile

Time (Hr) % drug release

1 12

2 26

4 53

6 76

8 90

12 101 Example 5:

Azithromycin dihydrate, Methocel 100 M, Sodium alginate, Microcrystalline cellulose, Crospovidone and Calcium sulfate dihydrate are individually weighed and sieved through # 40 mesh and the mixture is granulated with water for 10 minutes. The obtained wet mass is sieved through # 8 mesh and dried. The resulting dried granules are passed through # 30 mesh. Sodium bicarbonate and precipitated colloidal silicon dioxide are added to the dried granules and the final blend is lubricated with magnesium stearate and compressed into tablets.

Dissolution profile

Time (Hr) % drug release

1 2

2 18

4 41

6 56

8 67

12 84 Example 6

Clarithromycin, Methocel K 100 M, Sodium alginate, Sodium starch glycollate and calcium chloride are individually weighed and sieved through # 40 mesh and the mixture is granulated with isopropyl alcoho water (50: 50) for 10 minutes. The obtained wet mass is sieved through # 8 mesh and dried. The resulting dried granules are passed through # 30 mesh. Sodium bicarbonate and talc are added to the dried granules and the final blend is lubricated with magnesium stearate and compressed into tablets.

Dissolution profile

Example 7:

Sr. Ingredient mg/ tablet

No

1. Clarithromycin 250 mg 2. Methocel K 100 M 75 mg

3. Gellan gum 30 mg

4. Calcium bicarbonate 20 mg

5. Sodium starch glycollate 10 mg

6. Magnesium stearate 15 mg

7. Talc 10 mg

Example 8:

Sr. Ingredient mg/ tablet No

1. Azithromycin dihydrate 1121 mg

2. Methocel K 100 M 150 mg

3. Gellan gum 75 mg

4. Calcium carbonate 40 mg

5. Croscarmellose sodium 35 mg

6. Magnesium stearate 35 mg

7. Talc 15 mg

Example 9:

Sr. Ingredient mg/ tablet

No

1. Telithromycin 600 mg

2. Methocel K 14 M 120 mg

3. Sodium alginate 60 mg

4. Sodium bicarbonate 30 mg

5. Crospovidone 22 mg

6. Calcium stearate 35 mg

7. Talc 18 mg Example 10

Example 11

Sr. Ingredient mg/ tablet

No

1. Azithromycin dihydrate 250 mg (Equivalent to azithromycin)

2. Methocel K 100 M 40 mg

3. Sodium alginate 20 mg

4. Sodium bicarbonate 15 mg

5. Microcrystalline cellulose 22 mg

6. Crospovidone 06 mg

7. Calcium sulfate dihydrate 07 mg

8. Magnesium stearate 10 mg

9. Precipitated colloidal silicon dioxide 10 mg

Claims

We claim,

1. A gastroretentive delivery system of macrolide consisting of a hydrophilic swellable floating matrix system either alone or in combination with a bioadhesive system comprising:

e) macrolide in an amount of 10% to 98% w/w;

f) hydrophilic polymers in an amount of 0.1 % to 30% w/w;

g) in-situ gelling agents in an amount of 0.5% to 25% w/w and

h) superdisintegrants in an amount of 0.1% to 20% w/w of the total formulation.

2. The gastroretentive delivery system of macrolide as claimed in claim 1, wherein the macrolides are selected from a group consisting of erythromycin, azithromycin, clarithromycin, roxithromycin, dirithromycin spiramycin, josamycin, midecamycin, telithromycin and troleandamycin.

3. The gastroretentive delivery system of macrolide as claimed in claim 1, wherein the superdisintegrants are selected from a group consisting of crospovidone, croscarmellose sodium and sodium starch glycollate.

4. The gastroretentive delivery system of macrolide as claimed in claim 1, wherein the hydrophillic polymers are selected from a group consisting of cellulose, cellulose derivatives, cellulose esters, natural gums, polyvinylpyrrolidone, polyvinyl alcohol and poly(ethylene oxide).

5. The gastroretentive delivery system of macrolide as claimed in claim 1, wherein the in-situ gelling agents are selected from a group consisting of natural gums including gellan gum and locust bean gum, sodium alginate, cellulose esters, modified cellulose esters, acrylate, methacrylates copolymers, and co-block polymers of acrylates and acrylic acid derivatives, and ionic agents such as calcium chloride, calcium sulfate, calcium carbonate, calcium stearate, magnesium chloride, magnesium sulfate, magnesium carbonate, magnesium stearate, zinc chloride and zinc carbonate.

6. The gastroretentive delivery system of macrolide as claimed in claim 1, wherein the hydrophilic swellable matrix system is incorporated with an alkali-, as stabilizer.

7. The gastroretentive delivery system of macrolide as claimed in claim 6, wherein the stabilizer is selected from a group consisting of carbonates, phosphates and borates.

8. The gastroretentive. deli very system of macrolide as claimed in claim 7, wherein the stabilizer is preferably selected from a group consisting of sodium carbonate, sodium bicarbonate, magnesium carbonate, calcium carbonate, aluminium carbonate and zinc carbonate.