shalini nagarigari

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OSMOTIC DRUG DELIVERY SYSTEM

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Osmotic drug delivery system:

Osmotic drug delivery system AND RECENT ADVANCEMENT IN IT Presented by: Shalini Nagarigari, Bpharm, Arya College of Pharmacy, Kandi.

Introduction:

Introduction Osmosis can be defined as the net movement of water across a selectively permeable membrane driven by a difference in osmotic pressure across the membrane. It is driven by a difference in solute concentrations across the membrane that allows passage of water, but rejects most solute molecules or ions. Osmotic pressure is the pressure which, if applied to the more concentrated solution, would prevent transport of water across the semipermeable membrane. 2

Introduction:

Introduction The first osmotic effect was reported by Abbe Nollet in 1748. Later in 1877, Pfeffer performed an experiment using semi-permeable membrane to separate sugar solution from pure water. He showed that the osmotic pressure of the sugar solution is directly proportional to the solution concentration and the absolute temperature. In 1886, Vant Hoff identified an underlying proportionality between osmotic pressure, concentration and temperature. He revealed that osmotic pressure is proportional to concentration and temperature and the relationship can be described by following equation. 3

Introduction:

Introduction Π = p c RT Where, p = Osmotic pressure Π = osmotic coefficient c = molar concentration R = gas constant T = Absolute temperature 4

Introduction:

Introduction Solutions of different concentrations having the same solute and solvent system exhibit an osmotic pressure proportional to their concentrations. Thus a constant osmotic pressure, and thereby a constant influx of water can be achieved by an osmotic delivery system that results in a constant zero order release rate of drug. Osmotic pressure is used as driving force for these systems to release the drug in controlled manner. These systems can be used for both route of administration i.e. oral and parenterals . Oral osmotic systems are known as gastro-intestinal therapeutic systems (GITS). Parenteral osmotic drug delivery includes implantable pumps. 5

Introduction:

Introduction About 75 years after discovery of osmosis principle Rose and Nelson, the Australian scientists, initiated the osmotic drug delivery system. They developed an implantable pump, which consisted of three chambers: a drug chamber, a salt chamber contains excess solid salt, and a water chamber. The design and mechanism of this pump is comparable to modern push-pull osmotic pump. The major disadvantage of this pump was the water chamber , which must be charged before use of the pump. 6

Introduction:

Introduction 7 Modified version of Rose Nelson Pump Higuchi Leeper Pump Higuchi-Leeper pump

Introduction:

Introduction It has no water chamber , and the device is activated by water imbibed from the surrounding environment. The pump is activated when it is swallowed or implanted in the body. This pump consists of a rigid housing, and the semipermeable membrane is supported on a perforated frame. It has a salt chamber containing a fluid solution with excess solid salt. Recent modification in Higuchi-Leeper pump accommodated pulsatile drug delivery. Further simplified variant of Rose-Nelson pump was developed by Higuchi and Theeuwes. 8

Introduction:

Introduction This pump comprises a rigid, rate controlling outer semipermeable membrane surrounding a solid layer of salt coated on the inside by an elastic diaphragm and on the outside by the membrane. In use, water is osmotically drawn by the salt chamber, forcing drug from the drug chamber. 9

Advantages:

Advantages The delivery rate of zero-order is achievable with osmotic systems. Delivery may be delayed or pulsed, if desired. Higher release rates are possible with osmotic systems compared with conventional diffusion-controlled drug delivery systems . The release rate of osmotic systems is highly predictable and can be programmed by modulating the release control parameters. For oral osmotic systems, drug release is independent of gastric pH and hydrodynamic conditions. The release from osmotic systems is minimally affected by the presence of food in gastrointestinal tract. A high degree of in vivo- in vitro correlation (IVIVC) is obtained in osmotic systems. 10

disadvantages:

disadvantages 11

Classification:

Classification 12 Oral osmotic tablet

Criteria for selection of a drug :

Criteria for selection of a drug Short biological Half-life (2- 6 hrs) High potency Required for prolonged treatment (e.g: Nifedipine, Glipizide, Verapamil and Chlorpromazine hydrochloride). 13

Basic components:

Basic components Drug Osmotic agent Semi permeable membrane 14

Osmotic agents:

Osmotic agents Polymeric osmogents are mainly used in the fabrication of osmotically controlled drug delivery systems and other modified devices for controlled release of relatively insoluble drugs. Osmotic pressures for concentrated solution of soluble solutes commonly used in controlled release formulations are extremely high, ranging from 30 atm for sodium phosphate up to 500 atm for a lactose-fructose mixture. These osmotic pressures can produce high water flows across semipermeable membranes . 15

Semipermeable membrane:

Semipermeable membrane The membrane must possess certain performance criteria such as: Sufficient wet strength and water permeability Should be biocompatible Rigid and non-swelling Should be sufficient thick to withstand the pressure within the device. Any polymer that is permeable to water but impermeable to solute can be used as a coating material in osmotic devices. e.g. Cellulose esters like cellulose acetate, cellulose acetate butyrate, cellulose triacetate and ethyl cellulose and Eudragits. 16

Osmotic pump & its component:

Osmotic pump & its component 17

Recently in use osmotic pump :

Recently in use osmotic pump 18 Drug solution leaving via delivery portal Removable cap Flow moderator Semi permeable membrane Osmotic agent Flexible impermeable reservoir wall Reservoir

Elementry osmotic pump (EOP):

Elementry osmotic pump (EOP) EOP is the most basic device made up of a compressed tablet. The EOP consists of an osmotic core with the drug, surrounded by a semi permeable membrane . The semi permeable membrane is provided with a hole for the controlled delivery of the saturated solution of the drug formed as a result of imbibitions of water whose rate is determined by the fluid permeability of the membrane and the osmotic pressure of the compressed tablet when the dosage form is placed in the aqueous environment. Application : Moderately soluble drug. Normally EOP deliver 60 – 80 % of its content at constant rate. It has short lag time of 30 – 60 minute. 19

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20 Fig. : EOP Limitations: SPM should be 200-300 μ m thick to withstand pressure Thick coatings lowers the water permeation rate Applicable mostly for water soluble drugs

Controlled porosity osmotic pump:

Controlled porosity osmotic pump 21 It is laser or micro driven orifice. When Controlled Porosity Osmotic pump is placed in aqueous environment the water soluble component of coating dissolves and forms micropores in membrane and water diffuses inside the core through microporous membrane, setting up an osmotic gradiant and thereby controlling the release of drug.

Controlled porosity osmotic pump:

Controlled porosity osmotic pump A controlled porosity wall can be described as having a sponge .like appearance. Generally, materials producing from 5 to 95% pores with a pore size from 10A - 100µm can be used . The resulting membrane is substantially permeable to both water and dissolved solute. Water-soluble additives used for this purpose are dimethyl sulfone, saccharides, amino acids, sorbotil, etc. Core: API ± osmogents Coat: Semi permeable membrane with water soluble additives 22

Push-pull osmotic pump (PPOP):

Push-pull osmotic pump (PPOP) Core Tablet: Layer 1:  API ± osmogents Layer 2: Polymeric osmotic agents Coat: Semi permeable membrane with delivery orifice. It is a bilayer tablet coated with semi permeable membrane. The PPOP system consists of two compartments separated usually by an elastic diaphragm. The upper compartment contains the drug and is connected to the outside environment via a small delivery orifice. It is used for delivery of APIs having extremes of water solubility . Modifications can be done: - delayed push-pull - multi-layer push-pull - push-stick system 23

Push-pull osmotic pump (PPOP):

Push-pull osmotic pump (PPOP) 24

Sandwiched Osmotic tablets (SOTS):

Sandwiched Osmotic tablets (SOTS) It is composed of polymeric push layer sandwiched between two drug layers with two delivery orifices. When placed in the aqueous environment the middle push layer containing the swelling agents, swells and the drug is released from the delivery orifices. Advantage : the drug is released from the two orifices situated on opposite sides of the tablet 25

Sandwiched Osmotic tablets (SOTS):

Sandwiched Osmotic tablets (SOTS) 26

Osmotic pump:

Osmotic pump 27

alzet osmotic pump:

alzet osmotic pump 28

alzet osmotic pump:

alzet osmotic pump Design: Empty reservoir within the core of the pump is filled with the drug or hormone solution to be delivered and is surrounded by salt chamber with impermeable layer between them. Mechanism: Water enters into the salt chamber through semipermeable membrane and causes compression of flexible reservoir and delivery of drug solution. Application: To deliver drugs, hormones, and other test agents continuously at controlled rates from one day to six weeks. 29

alzet osmotic pump:

alzet osmotic pump 30

Marketed formulations:

Marketed formulations 31

Marketed formulations:

Marketed formulations 32

Question bank:

Question bank What is ODDS? Why it is required? Enumerate recent advance in controlled osmotic drug delivery system with their approaches. What are ideal properties of semi permeable membrane? Suggest few materials for this. Give advantage and disadvantage of osmotic drug delivery system. Give name of osmotic pumps. Give detail on elementary osmotic pump. 33

References:

References Gupta Roop, Gupta Rakesh, Basniwal Pawan k, Rathore Garvendras, Osmotically controlled oral drug delivery systems: a review, int. J. Ph. Sci., 2009, 1(2), 269-275. Gohel M.C Parikh .R.K , Shah. N.Y Osmotic drug delivery- an update, pharmainfo.net, 2009, 7(2). Lachman L., Liberman H. A., Kanig J. L., The theory and practise of industrial pharmacy. 2 nd Edition 1991, Varghese publishing house, Pg. 455. Aulton M. E., pharmaceutics the science of dosage form design. 2 nd Edition 2002, Churchill livingstone, Pg. 38, 39, 74, 304, 417. Ajay Babu, M. Prasada Rao, Vijaya Ratna J, Controlled-porosity osmotic pump tablets-an overview, jprhc. Shailesh Sharma. Osmotic controlled drug delivery. Pharmainfo.net. 2008; 6(3). 34

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Osmotic drug delivery system by SHALINI NAGARIGARI 36 THANK YOU

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