Osmotic Drug Delivery System

Osmotic drug delivery system

1. Osmotic drug delivEry system PRESENTED BY R.SHIVA SAI KIRAN 22PH203A09 M.PHARMACY(PHARMACEUTICS) ANURAG UNIVERCITY

2. Contents Introduction Advantages and Disadvantages Principle of osmosis Types of osmotic pumps Factors Affecting Release of drug from osmotic drug delivery system.

3. Introduction Osmotic drug delivery uses the osmotic pressure of drug or other solutes ( osmoagents ) for controled delivery of drugs . o smotic drug delivery has came a long way since australian physiologists Rose and Nelson developed an implantable pump in 1955 .

4. ADVANTAGES The delivery rate of zero order ( which is most desirable ) is achieved 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 . Production scale up is easy .

5. Disadvantages Expensive. chance of toxicity due to dose dumping . Rapid development of tolerance . hypersensitivity reaction may occur . integrity and consistency are difficult .

6. Principle of osmosis Osmosis refers to the process of movement of solvent from lower concentration of solute towards higher concentration of solute across the semi permeable membrane . Abbe Nollet first reported osmotic effect in 1748, but Pfeffer in 1877 had been the pioneer quantitative measurement of osmotic effect. Pfeffer measured the effect by utilizing a membrane which is selectively permeable to water but impermeable to sugar. The membrane separated sugar solution from pure water.

7. BASIC COMPONENTS OF OSMOTICPUMP OSMOGEN / OSMAGENT / OSMOTIC DRIVING AGENT For the selection of osmogen , the two most critical properties to be considered are osmotic activity and aqueous solubility. Osmotic agents are classified as, • Inorganic water soluble osmogens : Magnesium sulphate, s odium chloride, •Organic water soluble osmogens : Sorbitol, Mannitol. Organic polymeric osmogens : Na CMC, HPMC, HEMC,

8. SEMIPERMEABLE MEMBRANES semipermeable membrane must possess certain performance criteria: It must have sufficient wet strength and water permeability. It should be selectively permeable to water and biocompatible. Cellulose acetate is a commonly employed semipermeable membrane for the preparation of osmotic pumps.

9. HYDROPHILIC AND HYDROBHOBIC POLYMERS These polymers are used in the formulation development of osmotic systems containing matrix core. The selection of polymer is based on the solubility of drug as well as the amount and rate of drug to be released from the pump. The highly water soluble compounds can be co-entrapped in hydrophobic matrices and moderately water soluble compounds can be e ntrapped in hydrophilic matrices to obtain more controlled release.

10. WICKING AGENTS It is defined as a material with the ability to draw water into the porous network of a delivery device. The function of the wicking agent is to draw water to surfaces inside the core of the tablet, thereby creating channels or a network of increased surface area. Examples: colloid on silicon dioxide, kaolin, titanium dioxide, alumina, niacinamide,sodium lauryl sulphate (SLS) .

11. ELEMENTARY OSMOTIC PUMP (EOP) Rose Nelson pump was further simplified in theorem of elementary osmotic pump ( byTheeuwes , 1975) which made osmotic delivery as a major method of achieving controlled drug release. ELEMENTARY OSMOTIC PUMP (EOP) It essentially contains an active agent having a suitable osmotic pressure. It is fabricated as a tablet coated with semi permeable membrane, usually cellulose acetate. A small orifice is drilled through the membrane coating.

12. ELEMENTARY OSMOTIC PUMP (EOP)

13. This pump eliminates the separate salt chamber unlike others, When this coated tablet is exposed to an aqueous environment, the osmotic pressure of the soluble drug inside the tablet draws water through the semi permeable coating and a saturated aqueous solution of drug is formed inside the device. The membrane is non-extensible and the increase in volume due to imbibition of water raises the hydrostatic pressure inside the tablet, eventually leading to flow of saturated solution of active agent out of the device through the small orifice. The process continues at a constant rate till the entire solid drug inside the tablet is eliminated leaving only solution filled shell. This residual dissolved drug is delivered at a slower rate to attain equilibrium between external and internal drug solution.

14. Controlled Porosity Osnmotic Pump(CPOP) The delivery orifice is formed by incorporation of a leachable water-soluble component in the coating material . Drug release from the whole surface of device rather than from a single hole which may reduce stomach irritation problem .

15. Osmotic bursting osmotic pump Core: API ± osmogents Coat: Semi permeable membrane without delivery orifice When placed in aqueous environment, water is imbibed and hydraulic pressure is built up inside the system, then wall ruptures and the contents are released. It is used for pulsated release.

16. Multichamber osmotic pump Push Pull Osmotic System (PPOP) They contain two or three compartment separated by elastic diaphragm Upper compartment contain drug with or without Osmogen (drug compartment nearly 60 - 80 %)and lower compartment (Push compartment)contain Osmogen at 20- 40 %.It is a bilayer tablet coated with semi permeable membrane.

17. 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

18. A. Solubility . B. Osmotic pressure . C. Delivery orifice . D. Membrane type . Factors affecting release of medicament from Osmotic DDS