DESC:Field of Invention
The invention is related to a pharmaceutical osmotic delivery system, in particular, an osmotic drug delivery system for controlled delivery of anti-depressant without laser drilling technique.
Background of the invention 5
Desvenlafaxine (DSV) is an active metabolite of the third generation anti-depressant, venlafaxine. DSV is comparable to venlafaxine in efficacy and has lesser side effects. Venlafaxine is the treatment of choice for Major Depressive disorders. Venlafaxine is metabolized via cytochrome P450 (CYP)2D6 isoenzyme to an active metabolite, 0-desmethylvenlafaxine, which is also a SNRI like its parent compound. 10 Desvenlafaxine succinate (DVS) is the succinate salt monohydrate of this major metabolite. DSV, being a weak basic drug, dissolves easily in gastric fluids and is highly absorbed after oral administration, which exaggerates its side effects. This highlights the need to prepare extended release of DSV tablets to increase the compliance of patients suffering from depressive disorder and decrease side effects 15 compared to the immediate release formulation.
Conventional oral dosage forms of DSV have limited bioavailability and require frequent dosing of the drug to maintain the effective therapeutic concentration in the body. This result in poor patient compliance and fluctuations in the plasma drug levels and increase side effects. To overcome such problems and to enhance the 20 efficiency and bioavailability of the drug, modified drug delivery systems such as
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extended release delivery systems (controlled release; sustained release) and delayed release delivery systems have been developed which can prolong the release and absorption of the drug. And hence action of the drug in the body and decrease side effects.
Desvenlafaxine is available in the market as PRISTIQ (manufactured by Pfizer) in the 5 form of extended release tablets. DSV preparations that have been marketed include sustained-release preparations with different specifications, such as ordinary capsules, sustained-release tablets, sustained-release capsules, and sustained-release pellets. However, the DSV of common preparations has the problems of short half-life frequent administration of patients and large side effects due to fluctuation in the 10 blood concentrations.
In spite of the work done till date regarding DSV sustained release formulations there are still some challenges which are not solved in the prior art. To overcome the existing problems associated with formulating a stable and bioavailable DSV, inventors of the present invention have prepared a Controlled release osmotic 15 delivery device for DSV.
The release of drugs can be controlled by different techniques for example using a polymeric matrix or reservoir or using osmosis principle. Osmosis is defined as movement of water across the semi-permeable membrane by difference in osmotic pressure and osmotic system exploit this technique to develop an ideal controlled 20 drug delivery system. Since the release of drug is dependent on osmotic pressure,
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biological factors such as pH, presence of food and other drugs have no effect on the release of drug. Thus osmotic drug delivery system is an ideal approach to control the delivery of drug. These systems can be employed for oral route as well can be used as an implant.
An oral osmotic drug delivery system generally includes a core comprising drug with 5 excipients such as osmogens, a semipermeable coating system around the core and generally have at least one orifice for release of drug from the semipermeable membrane. The rate at which the core absorbs water depends on the osmotic pressure generated by the core components and the permeability of the semipermeable membrane [Eckenhoff B, et. al., Pharmaceutical Technology. 1981;5(1):35–44 & 10 Thombre AG, Journal of Controlled Release. 2004;94(1):75–89.] Thus, selection of components while designing osmotic drug delivery is a crucial factor.
The prior art teaches mechanical means such as laser, drill and/or etching apparatus, for making the orifice or preformed passage for drug release from the osmotic delivery device. However mechanical means have certain disadvantages such as the 15 cost of apparatus or device used for forming holes or passage is very high and required additional work force thus increases the production time. The involvement of laser drilling often leads to inadequate formation of holes due to missed drilling, over drilling, wrong drilling position and insufficient depth of drilling.
Different types of osmotic delivery devices have already been disclosed in the prior 20 art. One of the most commonly used osmotic delivery devices is the controlled porous
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osmotic drug delivery system which releases the drug through semi-permeable membrane. A controlled porous osmotic drug delivery system comprises a core and a semi-permeable membrane around the core, wherein the core comprises active agents, osmogens and other pharmaceutical acceptable excipients and a semi-permeable membrane around the core comprising polymer and pharmaceutical acceptable 5 excipients wherein the semi permeable membrane comprises atleast one orifice. The orifice(s) can be formed by mechanical means or by using pore forming agent(s). Thus instead of drilling orifice(s)/pore(s) for release of the drug, in case of controlled porous osmotic drug delivery device the drug release can be achieved through pores created by pore formers present in the semi-premeable membrane. 10
The semi-permeable membrane of a controlled porous osmotic delivery device plays an important role in the final bioavailability of the drug. The drug release depends upon hydrostatic pressure created by inlet water which enters through the semipermeable membrane, and the size and number of pores formed in the semi-permeable membrane. Thus the drug release from a Controlled porous osmotic pump 15 is dependent on the semi-permeable membrane.
The controlled porous osmotic devices disclosed in the prior art have been reported to generally suffer from an inability to dispense all or substantially all the active agent from the core prior to the loss of osmotic pressure that occurs at osmotic equilibrium.
For example, US 6,599,284 B2 tries to solve the problem associated with dispensing 20 of the active ingredient by forming a dedicated preformed passage in the semi
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permeable membrane which increases in size while using. But laser drilling is required to obtain the pre-formed passage way in the semipermeable membrane.
Similarly, US Patent No. 6,004,582 discloses a multi-layered osmotic device comprising a core surrounded by a semipermeable membrane having a preformed hole in it. The hole is subsequently plugged by an inert erodible water soluble coating 5 and then covered with a water soluble drug-containing coating.
U.S. Pat. No. 5,873,793 to Emerton et al. (Emerton et al. '793) and U.S. Pat. No. 5,376,771 to Roy (Roy '771) disclose laser apparatuses capable of simultaneously forming a plurality of holes on the semipermeable membrane of an osmotic device.
Thus there is still a need in the art for a controlled release osmotic delivery device 10 which delivers the drug through the pores formed in the semipermeable membrane without the need of additional drilling to dispense all or substantially all the active agent from the core prior to the loss of osmotic pressure that occurs at osmotic equilibrium.
The inventors of the present invention found that pore-formers present in semi-15 permeable membranes of controlled release osmotic delivery devices alone were not able to generate pores properly for the release of drug DSV from the membrane and the release of DSV was greatly affected due to inadequate pore formation thus resulting in poor dispensing of the drug from the osmotic tablets. Surprisingly, the inventors found that the problem can be solved by optimizing the semi-permeable 20 membrane and without any additional drilling. The optimizations of the
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semipermeable membrane were done by adding porosity enhancer in the coating solution. The addition of porosity enhancer while preparing semi-permeable membrane was also found to effectively improves and controls the size of pores for the release of DSV. Thus, as compared to existing oral osmotic drug delivery system the present invention provides a simple and controlled porous osmotic drug delivery 5 system without the need to be drilled and improves the delivery of drug through the semi-permeable membrane by using porosity enhancers.
Objectives of the Invention
The principal objective of the present invention is to provide a pharmaceutical composition comprising antidepressant and process of preparation thereof wherein 10 the composition is an osmotic drug delivery system and antidepressant is desvenlafaxine or pharmaceutical acceptable salt thereof and wherein the composition is stable and bioavailable.
Another objective of the present invention is to provide an osmotic drug delivery system for controlled or extended delivery of desvenlafaxine or pharmaceutical 15 acceptable salt thereof, wherein the osmotic system is in form of tablets, capsule, pellets, granules. In some embodiment, an osmotic drug delivery system is tablet.
A further objective of the present invention is to provide controlled porous osmotic drug delivery system in form of oral tablet comprising a core comprising active agent and pharmaceutical acceptable excipients; and a semi-permeable membrane 20
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surrounding the core, comprising a mixture of cellulosic polymer and pore formers, porosity enhancers and coating solvent.
Summary of the invention
The present invention provides a simple controlled osmotic drug delivery system comprising antidepressant wherein the controlled drug delivery system is controlled 5 porous osmotic drug delivery system which provide controlled or extended delivery of drug to the target site and increase bioavailability of drug. The controlled osmotic drug delivery system is in form of oral tablet which comprises a core having antidepressant, osmogent and other pharmaceutical acceptable excipients and a semi-permeable membrane around the core wherein the semi-permeable membrane 10 comprises cellulosic polymer and pore formers, porosity enhancers and coating solvent.
Brief Description of Drawings:
Figure 1 represent comparative dissolution profile (Osmotic tab of present invention against reference marketed product) 15
Detailed Description
The present invention provides a simple, cost effective osmotic drug delivery system comprising anti-depressant agent that provide controlled or extended release of the drug with increased bioavailability without the need of laser drill technology.
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A controlled porous osmotic drug delivery system in form of tablet comprises a core and a semi-permeable membrane around the core, wherein the core comprises anti-depressant agents, osmogens and pharmaceutical acceptable excipients and wherein the semi-permeable membrane comprises a polymer, pore-formers, porosity enhancers and coating solvent. The pore formers provide multiple orifice or delivery 5 ports for controlled release of active agent. The inventors of the present invention found that the pore-formers alone were not able to generate pores properly and the release of drug from the membrane was greatly affected due to inadequate pores formation. The inventors of the present invention unexpectedly were able to establish that adding porosity enhancer in the coating solution while preparing semi-permeable 10 membrane effectively improves and increases the size of pores during use and thereby solving the problems associated with low dispensation of the drug from the osmotic tablet. Thus, as compared to existing oral osmotic drug delivery system the present invention provides a simple and controlled porous osmotic drug delivery system without the need to be drilled improves the delivery of drug by using porosity 15 enhancers.
Thus, in an embodiment the present invention provides a controlled osmotic drug delivery system comprising antidepressants and pharmaceutical acceptable excipients wherein the osmotic drug delivery system is an oral controlled porosity osmotic drug delivery system. The oral controlled porosity osmotic drug delivery system of present 20 invention comprises a core having antidepressant, osmogens and pharmaceutical
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acceptable excipients and a semi-permeable membrane around the core wherein the semi-permeable membrane comprises cellulosic polymer, pore-formers and porosity enhancers
In an embodiment, the controlled porosity delivery system of present invention is an oral delivery system, wherein oral drug delivery system is selected from tablet, 5 capsule, pills or granules. In most preferred embodiment the oral drug delivery system is a controlled porosity osmotic tablet.
In another embodiment, the controlled porosity osmotic tablet of present invention comprises:
a) a core comprising an antidepressant, osmogens and pharmaceutical excipients 10
b) a semi-permeable membrane around the core comprising polymer, pore formers, porosity enhancer and coating solvent In an embodiment the core of porosity osmotic tablet comprises antidepressant wherein antidepressant is desvenlafaxine or pharmaceutically acceptable salts thereof. In a preferred embodiment the core comprises desvenlafaxine succinate in an amount 15 ranging from 35 to 60 % based on total weight of core, and preferably in an amount ranging from 40 to 50 % based on total weight of core. In an embodiment the osmogent present in the core of the controlled porosity osmotic tablet can be selected from hydrophilic compounds which imbibe biological fluids from semi-permeable membrane which on dissolution increases the osmotic pressure 20
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inside the core and pushes the drug from core through pores present in semi-permeable membrane. The osmogent in the present invention are selected from inorganic salt such as magnesium chloride or magnesium sulfate, lithium, sodium or potassium chloride, lithium, sodium or potassium hydrogen phosphate, lithium, sodium or potassium dihydrogen phosphate, salts of organic acids such as sodium or 5 potassium acetate, magnesium succinate, sodium benzoate, sodium citrate or sodium ascorbate; carbohydrates such as mannitol, sorbitol, arabinose, ribose, xylose, glucose, fructose, mannose, galactose, sucrose, maltose, lactose, raffinose. In a preferred embodiment the osmogent is potassium chloride in an amount ranging from 0.5 to 5% based on total weight of core. 10 In an another embodiment the core of porosity osmotic tablet further comprises pharmaceutical excipients wherein excipients are selected from group consisting of binder, diluent, glidant, lubricant and anti-adherent or combinations thereof. In one embodiment the core of the osmotic tablet comprises one or more diluents selected from lactose e.g., directly compressible lactose, lactose monohydrate, lactose 15 anhydrous, and spray dried lactose; microcrystalline cellulose sugar alcohols, e.g., sorbitol, erythritol, xylitol, and mannitol, starch. In preferred embodiment one or more diluent is lactose monohydrate and mannitol present in an amount ranging from 5 to 40 % based on total weight of core. In an another embodiment the core of porosity osmotic tablet comprises binder 20 wherein binder is selected from microcrystalline cellulose, starch, pregelatinized
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starch, polyethylene glycol (PEG), sorbitol, celluloses for example hydroxypropyl methylcellulose (HPMC); hydroxy ethylcellulose, hydroxypropyl cellulose, methylcellulose, and ethylcellulose, povidone or combination thereof. In preferred embodiment binder is hydroxypropyl methylcellulose (HPMC) present in an amount ranging from 1 to 5% based on total weight of core. 5 In an another embodiment the core of porosity osmotic tablet comprises disintegrant selected from croscarmellose sodium, crospovidone, sodium starch glycolate, chitin and combination thereof. In a preferred embodiment disintegrant is croscarmellose sodium present in an amount ranging from 0.5 to 2% based on total weight of core. In an another embodiment the core of porosity osmotic tablet comprises glidant 10 selected from calcium phosphate tribasic, magnesium silicate, colloidal silicon dioxide, and talc or a combination thereof. In a preferred embodiment glidant is colloidal silicon dioxide present in an amount ranging from 1 to 5% based on total weight of core. In an another embodiment the core of porosity osmotic tablet comprises lubricant 15 selected from group consisting of sodium stearyl fumarate, magnesium stearate, calcium stearate, stearic acid, talcum and colloidal anhydrous silica and combinations thereof. In a preferred embodiment lubricant is magnesium stearate present in an amount ranging from 1 to 5% based on total weight of core. In an another embodiment the core of porosity osmotic tablet comprises anti-adherent 20 selected from group consisting of starch, cellulose, talcum, colloidal silicon dioxide,
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magnesium stearate or combinations thereof. In a preferred embodiment anti-adherent is talcum present in an amount ranging from 1 to 5% based on total weight of core. In a preferred embodiment the core of present invention comprises: a. Desvenlafaxine succinate in an amount ranging from 40 to 50 % based on total weight of core. 5 b. potassium chloride as an osmogent in an amount ranging from 0.5 to 5% based on total weight of core. c. hydroxypropyl methylcellulose (HPMC) as a binder present in an amount ranging from 1 to 5% based on total weight of core. d. croscarmellose sodium as a disintegrant present in an amount ranging from 0.5 to 10 2% based on total weight of core. e. colloidal silicon dioxide as glidant present in an amount ranging from 1 to 5% based on total weight of core f. magnesium stearate as lubricant present in an amount ranging from 1 to 5% based on total weight of core. 15 g. Talcum as anti-adherent present in an amount ranging from 1 to 5% based on total weight of core. h. lactose monohydrate and mannitol as diluent present in an amount ranging from 5 to 40 % based on total weight of core. The present invention provides a controlled porosity osmotic tablet wherein the 20 composition comprises a core having active agent, osmogent and other
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pharmaceutical acceptable excipients wherein the core is coated with water permeable polymer coating which is permeable to aqueous fluids but impermeable to core contents thus act as a semi-permeable membrane. In an embodiment of the present invention, the osmotic drug delivery tablets comprise a semi-permeable membrane wherein the polymer used for forming the 5 semi-permeable membrane are cellulose derivatives selected from cellulose esters, cellulose diesters, cellulose triesters, cellulose ethers, cellulose ester-ethers, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose acetate proprionate, and cellulose acetate butyrate or combinations thereof. In a preferred embodiment the semi-permeable membrane is made up of cellulose acetate present in an amount 10 ranging from 5 to 20% based on total weight of the composition. In an embodiment, the semi-permeable membrane comprises pore formers already present in the polymer, wherein the pore-former is a hydrophilic polymer which on contact with fluid leached out from the membrane forming multiple pores for the release of drug from the membrane. 15 In an embodiment of the present invention the semi-permeable membrane comprises porosity enhancer which increases and controls the size of pores thereby enhancing the drug dispensing activity through semi-permeable membrane without the need of additional drilling. In an another embodiment the semi-permeable membrane comprises porosity 20 enhancer such as potassium chloride, potassium sulfate, calcium chloride, and magnesium sulfate, sodium chloride, sodium bicarbonate, mannitol, sodium sulfate,
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calcium phosphate. In most preferred embodiment the porosity enhancer is mannitol present in an amount ranging from 0.5-2 % based on the total weight of composition. In a preferred embodiment the present invention provides a polymer coating around the core which act as a semi-permeable membrane comprising following ingredients: i. Water permeable polymer present in an amount ranging from 5 to 20% based 5 on total weight of the composition, wherein polymer coating further comprises hydrophilic pore-formers. ii. Porosity enhancer present in an amount ranging from 0.5-2 % based on the total weight of composition.
In another embodiment the present invention provides a method of preparation of 10 controlled porosity osmotic tablet comprising:
Preparation of core: Active agent along with osmogent and other pharmaceutically acceptable excipients were dry or wet mixed to form granules and compressed to form tablets.
The compressed tablets were further coated with polymer coating comprising a 15 cellulose polymer, pore former and porosity enhancer to form a controlled porosity osmotic drug delivery system.
In a preferred embodiment the present invention provides a controlled porosity osmotic tablet comprising:
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A core comprising: desvenlafaxine succinate as active agent present in an amount ranging from 40-50% based on total weight of core, lactose monohydrate and mannitol as diluent present in an amount ranging from 5-40% based on total weight of core, potassium chloride as osmogent present in an amount ranging from 0.5-5% based on total weight of core, hydroxy propyl cellulose (HPMC) as 5 binder present in an amount ranging from 1-5% based on total weight of core,crosscarmellose sodium as disintegrant present in an amount ranging from 0.5-2% based on total weight of core, colloidal silicon dioxide as glidant present in an amount ranging from 1-5% based on total weight of core, talcum as anti-adherent present in an amount ranging from 1-5% based on total weight of 10 core,magnesium sterate as lubricant present in an amount ranging from 1-5% based on total weight of core.
Semi-permeable membrane made up of cellulose acetate as polymer around the core present in amount ranging from 5-20% based on total weight of composition wherein the membrane further comprises water soluble pore formers and 15 mannitol as porosity enhancer present in an amount ranging from 0.5-2% based on total weight of composition.
In an embodiment the present invention provides a simple, stable controlled porosity osmotic drug delivery system comprising a tablet coated with cellulose acetate as a semipermeable membrane wherein the membrane comprising porosity enhancer to 20 improve the release of desvenlafaxine succinate from the membrane. The
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semipermeable membrane acts a protective barrier or coating to control the release of drug over longer period of time. In an embodiment the present controlled porosity tablet provide a controlled release over 24 hours. The in vitro release profile shows that more 60% of drug release over 12 hours and more than 85% of drug releases over 24 hours. 5
The present invention is illustrated below by reference to the following examples. However, one skilled in the art will appreciate that the specific methods and results discussed are merely illustrative of the invention, and not to be construed as limiting the invention, as many variations thereof are possible without departing from the spirit and scope of the invention. 10
Example-1 Formula for Desvenlafaxine controlled porosity tablet
S.NO.
INGREDIENTS
%
FUNCTION
1
Desvenlafaxine succinate 40-50
Active agent
2
Lactose monohydrate 5-40
Diluent
3
Mannitol 5-40
Diluent
4
Potassium chloride
0.5-5
Osmogent
Binder Material
5
HPMC (E-5)
1-5
Binder
6
Purified water
q.s.
solvent
Lubrication Material
18
Example 2 – Comparative experimental studies Dissolution profile of the formulation prepared based on the present invention against the marketed product Pristiq 50mg was studied. Figure 1 provides the comparative dissolution profile of osmotic tablets of the present invention against marketed 5 product Desvenlafaxine tablets (Pristiq 50mg). From Fig 1 it can be seen that the osmotic tablets of the present invention showed comparable or better dissolution profile compared to marketed product.
10
7
Crosscarmellose sodium
0.5-2
Disintegrant
8
Mannitol (pearlitol SD 200) 5-40
Diluent
9
Colloidal silicon dioxide
1-5
Glidant
10
Talcum
1-5
Anti-adherent
11
Magnesium stearate
1-5
Lubricant
Coating Material
16
Cellulose acetate
5-20
Coating polymer
17
Acetone
q.s.
Coating solvent
18
Mannitol 0.5-2
Porosity enhancer
19
Purified water
q.s.
solvent
19
Claims:
I/We Claims:
1. An osmotic drug delivery system comprising:
a) a core comprising an antidepressant, osmogens and pharmaceutical excipients 5
b) a semi-permeable membrane surrounding the core comprising polymer, pore formers, porosity enhancer and coating solvent
2. An osmotic drug delivery system as claimed in claim 1, wherein said osmotic drug delivery system is an oral controlled porosity osmotic tablet.
3. A controlled porosity osmotic tablet as claimed in claim 2 wherein 10 antidepressant is Desvenlafaxine or pharmaceutically acceptable salts thereof more preferably Desvenlafaxine succinate.
4. A controlled porosity osmotic tablet as claimed in claim 2 wherein osmogens is potassium chloride in an amount ranging from 0.5 to 5% based on total weight of core. 15
5. A semi-permeable membrane as claimed in claim 2 wherein semi-permeable membrane is made of polymer selected from cellulose acetate present in an amount ranging from 5 to 20% based on total weight of the composition.
6. A semi-permeable membrane as claimed in claim 2 further comprises pore formers wherein pore formers is a hydrophilic polymer which on contact with 20
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fluid leached out from the membrane forming multiple pores for the release of drug from the membrane.
7. A semi-permeable membrane as claimed in claim 1, further comprising porosity enhancer wherein porosity enhancer is mannitol present in an amount ranging from 0.5-2 % based on the total weight of composition. 5
8. A controlled porosity osmotic tablet as claimed in claim 1 wherein the core comprises:
i. Desvenlafaxine succinate in an amount ranging from 40 to 50 % based on total weight of core.
ii. potassium chloride as an osmogent in an amount ranging from 0.5 to 10 5% based on total weight of core.
iii. hydroxypropyl methylcellulose (HPMC) as a binder present in an amount ranging from 1 to 5% based on total weight of core.
iv. croscarmellose sodium as a disintegrant present in an amount ranging from 0.5 to 2% based on total weight of core. 15
v. colloidal silicon dioxide as glidant present in an amount ranging from 1 to 5% based on total weight of core
vi. magnesium stearate as lubricant present in an amount ranging from 1 to 5% based on total weight of core.
vii. Talcum as anti-adherent present in an amount ranging from 1 to 5% 20 based on total weight of core.
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viii. lactose monohydrate and mannitol as diluent present in an amount ranging from 5 to 40 % based on total weight of core.
9. The semi-permeable membrane as claimed in claim 1 acts a protective barrier or coating to control the release of Desvenlafaxine over 24 hours wherein in-vitro profile shows that more 60% of drug release over 12 hours and more 5 than 85% of drug releases over 24 hours.
10. A method of preparation of controlled porosity osmotic tablet comprising:
a) Desvenlafaxine along with osmogent and other pharmaceutically acceptable excipients were dry or wet mixed to form granules and compressed to form tablets.
b) The compressed tablets were further coated with polymer coating comprising a cellulose polymer, pore former and porosity enhancer to form a controlled porosity osmotic drug delivery system.
Dated this August 01st, 2022
For Akums Drugs & Pharmaceuticals Ltd.
Siddhartha Dulakakhoria
(Authorized representative for Applicant)

ABSTRACT Osmotic drug delivery system with enhanced porous semi-permeable membrane
The invention is related to an oral controlled osmotic drug delivery system comprising antidepressant wherein the controlled osmotic delivery system is an oral controlled porous osmotic drug delivery system. The present invention provides a 5 simple and controlled porous osmotic drug delivery system without the need to be drilled and improves the delivery of drug through the semi-permeable membrane by using porosity enhancers. ,CLAIMS:1. An osmotic drug delivery system comprising:
a) a core comprising an antidepressant, osmogens and pharmaceutical excipients
b) a semi-permeable membrane surrounding the core comprising polymer, pore formers, porosity enhancer and coating solvent
2. An osmotic drug delivery system as claimed in claim 1, wherein said osmotic drug delivery system is an oral controlled porosity osmotic tablet.
3. A controlled porosity osmotic tablet as claimed in claim 2 wherein antidepressant is Desvenlafaxine or pharmaceutically acceptable salts thereof more preferably Desvenlafaxine succinate.
4. A controlled porosity osmotic tablet as claimed in claim 2 wherein osmogens is potassium chloride in an amount ranging from 0.5 to 5% based on total weight of core.
5. A semi-permeable membrane as claimed in claim 2 wherein semi-permeable membrane is made of polymer selected from cellulose acetate present in an amount ranging from 5 to 20% based on total weight of the composition.
6. A semi-permeable membrane as claimed in claim 2 further comprises pore formers wherein pore formers is a hydrophilic polymer which on contact with fluid leached out from the membrane forming multiple pores for the release of drug from the membrane.
7. A semi-permeable membrane as claimed in claim 1, further comprising porosity enhancer wherein porosity enhancer is mannitol present in an amount ranging from 0.5-2 % based on the total weight of composition
8. A controlled porosity osmotic tablet as claimed in claim 1 wherein the core comprises:
i. Desvenlafaxine succinate in an amount ranging from 40 to 50 % based on total weight of core.
ii. potassium chloride as an osmogent in an amount ranging from 0.5 to 5% based on total weight of core.
iii. hydroxypropyl methylcellulose (HPMC) as a binder present in an amount ranging from 1 to 5% based on total weight of core.
iv. croscarmellose sodium as a disintegrant present in an amount ranging from 0.5 to 2% based on total weight of core.
v. colloidal silicon dioxide as glidant present in an amount ranging from 1 to 5% based on total weight of core
vi. magnesium stearate as lubricant present in an amount ranging from 1 to 5% based on total weight of core.
vii. Talcum as anti-adherent present in an amount ranging from 1 to 5% based on total weight of core.
viii. lactose monohydrate and mannitol as diluent present in an amount ranging from 5 to 40 % based on total weight of core.
9. The semi-permeable membrane as claimed in claim 1 acts a protective barrier or coating to control the release of Desvenlafaxine over 24 hours wherein in-vitro profile shows that more 60% of drug release over 12 hours and more than 85% of drug releases over 24 hours.
10. A method of preparation of controlled porosity osmotic tablet comprising:
a) Desvenlafaxine along with osmogent and other pharmaceutically acceptable excipients were dry or wet mixed to form granules and compressed to form tablets.
b) The compressed tablets were further coated with polymer coating comprising a cellulose polymer, pore former and porosity enhancer to form a controlled porosity osmotic drug delivery system.