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The document discusses rate-controlled drug delivery systems (CDDS), including definitions, types, advantages, and disadvantages. It highlights various systems, such as sustained release and controlled release, designed to provide prolonged therapeutic effects through predictable drug release. Specific examples, such as Progestasert and Nitro-Dur, illustrate different formulations and their mechanisms of action.
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- 1. VariousVarious raTE-CoNTroLLEDraTE-CoNTroLLED DruG DELiVErYDruG DELiVErY sYsTEMssYsTEMs PrEsENTED BY :- ishiTa BajPai Masters in Pharmaceutics
- 2. Contents : Introduction : definition of controlled drug delivery systems (C.D.D.S) Advantantages and Disadvantages Types of rate controlled drug delivery systems Examples of each device and their functioning June 5, 2016 2
- 3. INTRODUCTION i. Sustained release, ii. sustained action, iii. controlled release, iv. extended action, v. timed release dosage forms Are the terms used to identify drug delivery systems that are designed to achieve a prolonged therapeutic effect by continuously releasing medication over an extended period of time after the administration of single dose. June 5, 2016
- 4. June 5, 2016 4 Controlled release : Usually represents those systems from which therapeutic agents may be AUTOMATICALLY DELIVERED at PREDEFINED RATES over a long period of time. It also implies a predictability & reproducibility in the drug release kinetics, which means that the release of drug ingredient from a controlled delivery system proceeds at a rate profile that is not only predictable kinetically, but also reproducible from one unit to another. Sustained Release : Describes a pharmaceutical dosage form formulated to RETARD the release of a therapeutic agent such that its appearance in the systemic circulation is delayed &/or prolonged & its plasma profile is sustained in duration.
- 5. ADVANTAGES : 1. Less drug blood levels fluctuation. 2. dosing frequency reduces. 3. Improved patient convenience & compliance. 4. Avoidance of night time dosing. 5. More uniform effect. 6. Reduction in GI irritation and dose related side effects June 5, 2016 5
- 6. DisadvantagesDisadvantages 1. Decreased systemic availability in comparison to immediate release conventional dosage forms. 2. Poor in vivo – in vitro correlation. 3. Possibility of dose dumping. 4. Retrieval of drug is difficult. 5. Higher cost of formulation. June 5, 2016 6
- 7. CLASSIFICATION Based on their technical sophistication : Rate preprogrammed drug delivery system Activation-modulated drug delivery system Feedback-regulated drug delivery system Site targeting drug delivery system June 5, 2016 7
- 8. RATE PRE-PROGRAMMEDRATE PRE-PROGRAMMED DRUG DELIVERY SYSTEMDRUG DELIVERY SYSTEM In this group , the release of drug molecule from the system has been pre-programmed at specific rate profile. June 5, 2016 8
- 9. RATE PRE-PROGRAMMED CLASSIFICATION 1. Polymer membrane permeation-controlled drug delivery system 2. Polymer matrix diffusion-controlled drug delivery system 3. Micro-reservoir partition-controlled drug delivery system June 5, 2016 9
- 10. 1.Polymer Membrane Permeation-1.Polymer Membrane Permeation- controlled Drug Delivery Systemcontrolled Drug Delivery System Herein, drug is totally or partially encapsulated within drug reservoir. Its drug release surface is covered by a rate-controlling polymeric membrane having a specific permeability. Drug reservoir may exist in solid, suspension or solution form. Polymeric membrane may be nonporous or microporous i.e semipermeable membrane. Encapsulation of the drug formulation inside the reservoir compartment is accomplished by injection,spray-coating,capsulation or micro-encapsulation. June 5, 2016 10 June 5, 2016 1010 Polymer membrane Drug reservoir Drug release
- 11. Drug release is controlled by : Partition coefficient of the drug molecule. Diffusivity of the drug molecule. The thickness of the rate controlling membrane. June 5, 2016 11
- 12. Progestasert intra-uterine device Example #1 June 5, 2016 12
- 13. Progestasert Intra UterineProgestasert Intra Uterine DeviceDevice arrangement : drug reservoir (D.R) = progesterone -barium sulphate suspension in silicone medical fluid. D.R encapsulated in vertical limb of a T- shaped device walled by a non-porous membrane of ethylene-vinyl acetate co- polymer. Designed to deliver natural progesterone continuously in uterine cavity at a daily dosage rate of at least 65 μg/day to achieve contraception for 1 year. June 5, 2016 13
- 14. June 5, 2016 14 Example #2 Ocusert
- 15. In the Ocusert system the drug reservoir is a thin disk of Pilocarpine alginate complex sandwitched between two transparent sheets of etylene vinyl acetate copolymer membrane. Microporous membrane permit the tear fluid to penetrate into the drug reservoir compartment to disssolve pilocarpine from the complex Pilocarpine molecules are then released at a constant rate of either 20or 40 µg/hr for the management of glaucoma for upto 7 days June 5, 2016 15
- 16. D Example Transderm- Nitro June 5, 2016 16 Adhesive layer
- 17. Transderm Nitro: Working Drug resevoir , nitroglycerine-lactose triturate dispersion in the silicon medical fluid, encapsulated in thin ellipsoidal patch. It is constructed from a drug impermeable metallic plastic laminate as the backing membrane and a constant surface of rate controlling microsporous membrane of etylene- vinyl acetate copolymer as the drug releasing surface Deliver nitroglycerine at dosage rate of 0.50 mg/cm²/day for transdermal absorption to provide daily relief from Angina attacks June 5, 2016 17
- 18. 2.Polymer Matrix Diffusion-controlled Drug2.Polymer Matrix Diffusion-controlled Drug Delivery SystemDelivery System Drug reservoir is prepared by homogeneously dispersing drug particle in rate controlling polymer matrix from either a lipophilic or a hydrophilic polymer. The drug dispersion in the polymer matrix is accomplished by either, 1. blending therapeutic dose of drug with polymer or highly viscous base polymer, followed by cross linking of polymer chains. OR 2. mixing drug solid with rubbery polymer at elevated temp. 18 18 Drug dispersed in polymer matrix Polymer membrane drug release Drug depletion zone drug release
- 19. The rate of the drug release from this system, Q = (2ACRDp)1/2 t½ Where, Q/t1/2 - rate of release of drug A – initial drug loading dose in the polymer matrix CR – drug solubility in polymer Dp – drug diffusivity in polymer matrixJune 5, 2016 19
- 20. Release of drug molecule is controlled by Loading dose Polymer solubility of drug Drug diffusivity in polymer matrix. Example . Nitro-Dur : Nitro-Dur is a transdermal system contains nitroglycerin in acrylic-based polymer adhesives with a resinous cross-linking agent to provide a continuous source of active ingredient. June 5, 2016 20
- 21. Nitro dur 21 It is designed for application on to intact skin for 24 hrs to provide a continuous transdermal infusion of nitroglycerin at dosage rate of 0.5 mg/cm2 /day for the treatment of angina pectoris.
- 22. 3.Microreservior Partition-controlled3.Microreservior Partition-controlled Drug Delivery SystemDrug Delivery System Here, drug reservoir is fabricated by micro dispersion of an aqueous Suspension of drug in biocompatible polymer such as silicon elastomers to form homogeneous dispersion . Depending upon the physicochemical properties of drugs & desired rate of drug release, the device can be further coated with a layer of biocompatible polymer to modify the mechanism & the rate of drug release. June 5, 2016 22 June 5, 2016 22 Microdispersion of drug in biocompatable polymer Polymer membrane drug release.
- 23. Release of drug molecules from this type of system can follow either a dissolution or a matrix diffusion controlled process Release of drug molecule is controlled by, Partition coefficient Diffusivity of drug Solubility of drug June 5, 2016 23
- 24. Example #1: Syncro Mate - C June 5, 2016 24
- 25. June 5, 2016 25 It is fabricated by dispersing the drug reservoir, which is a suspension of Norgestomet in an aqueous solution of PEG 400, in a viscous mixture of silicone elastomer, After catalyst addition, suspension will be delivered into silicone medical grade tubing, which serves as mold as well as the coating membrane & then polymerized in situ. The polymerized drug polymer composition is then cut into a cylindrical drug delivery device with the open ends. It is designed to be inserted into the subcutaneous tissue of the livestock’s ear flap & to release Norgestomet for up to 20 days for control of estrus & ovulation as well as for up to 160 days for growth promotion.
- 26. Transdermal Nitro disc June 5, 2016 26
- 27. June 5, 2016 27 Drug reservoir is formed by a suspension of nitroglycerine and lactose triturate in aqueous solution of 40% polyethylene glycol 400 and dispersing it with isopropyl palmitate as dispersing agent , in a mixture of viscous silicone elastomer. Drug polymer dispersion is then molded to form a solid medicated disk in situ on a drug –impermeable metallic plastic laminate, with surrounding adhesive rim, by injections molding under instantaneous heating. Transdermal administration of nitroglycerine at a daily dosage of 0.5 mg/cm² for once a day medication of angina pectoris.
- 28. IshIta BajpaI Thank you friends and viewersThank you friends and viewers June 5, 2016 28