Novel drug delivery systems a research 2.pptx

novel drug delivery system ppt

1. NOVEL DRUG DELIVERY SYSTEM PART 2 www.medacademy.org.in

2. Microencapsulation is a process by which very tiny droplets or particles of liquid or solid material are surrounded or coated with a continuous film of polymeric materials. Particles having a diameter between 3-800µm are known as micro particles. Microcapsules can be classified into three types. As follow as- (1) Mononuclear-Contain the shell around the core. (2) Polynuclear-Having many cores enclosed within a shell. (3) Matrix type- Distributed homogeneously into the shell material. 2 www.medacademy.org.in MICROENCAPSULATION

3. ADVANTAGES: ⚫ To increase bioavailability. ⚫ To alter the drug release. ⚫ To improve the patient’s compliance. ⚫ To decrease the evaporation rate of the core material. ⚫ To produce a targeted drug delivery. ⚫ To convert liquid to solid form. DISADVANTAGES: ⚫ Difficult to achieve continuous and uniform film. ⚫ The shelf life of hygroscopic drugs is reduced. ⚫ Polymers may produce toxic effects. ⚫ Costly. 3 www.medacademy.org.in MICROENCAPSULATION

4. APPLICATIONS OF MICROENCAPSULATION ⚫ To improve the flow properties. E.g.=Thiamine ⚫ To enhance the stability. E.g.=Vitamins ⚫ To reduce the volatility of materials. E.g. =Methyl salicylate ⚫ To mask the unpleasant taste and odour. E.g.=castor oil ⚫ To convert liquids into solids. E.g.=castor oil ⚫ To reduce gastric irritation. E.g.= indomethacin 4 www.medacademy.org.in MICROENCAPSULATION

5. Transdermal delivery systems are topically administered medications in the form of patches that deliver drugs for systemic effects at a predetermined and controlled rate. ADVANTAGES 1. Drugs with very short half-lives e.g. nitroglycerine when administered as transdermal patches, release medicaments at a constant rate for a time period more than that obtainable with oral formulations. 2. Drugs with narrow therapeutic indices can be safely administered since better control of release is possible. 3. The noninvasive nature of these systems permits easy removal and termination of drug action in situations of toxicity. 4. Problems encountered with oral administration like degradation, gastric irritation, first-pass effect, etc. are avoid should ideally be below 800-1000). 5 www.medacademy.org.in TRANSDERMAL DRUG DELIVERY SYSTEM

6. The route is unsuitable when 1.The drug dose is large 2.The drug has a large molecular size (which makes absorption difficult, should ideally be below 800-1000). 3. The drug is skin-sensitising and irritating. 4. The drug is metabolised in the skin. 5. The drug undergoes protein binding in the skin. 6, the drug is highly lipophilic or hydrophilic (should be moderately soluble in both oil and water). Other disadvantages of such systems include 1. Variation in absorption efficiency at different sites of the skin, 2. The difficulty of adhesion to certain skin types and 3. Length of time for which a patch can be left on any area due to permeability changes (usually not more than 7 to 10 days). 6 www.medacademy.org.in TRANSDERMAL DRUG DELIVERY SYSTEM

7. Transdermal drug delivery devices can be divided into broad categories based on the mechanism by which drug release is controlled: 1.Monolithic (or matrix) systems. 2. Reservoir (or membrane) systems The choice of a monolithic or reservoir type of system for controlling drug release depends upon the major rate-limiting step in the absorption of drugs from such devices. The two rate-limiting steps are: 1. Rate of drug diffusion from the device, R1, and 2. Rate of drug permeation through the stratum corneum, R2. The overall rate of drug transport is proportional to the sum (R1 + R2). 7 www.medacademy.org.in TRANSDERMAL DRUG DELIVERY SYSTEM

8. MONOLITHIC (OR MATRIX) DEVICES These devices are used when R2 is the rate-controlling step (R₂ < R₁) and the drug has a large therapeutic index so that overdosing does not precipitate toxic reactions. The two categories of matrix devices are one in which the drug is dissolved (usually below saturation levels) in the polymer matrix and the other in which the drug is dispersed (generally much above saturation levels). The polymers employed for matrix systems may be hydrophilic or lipophilic and include PVC, PVP, polysaccharides, polyesters, microporous polypropylene and ethylene vinyl acetate copolymers. 8 www.medacademy.org.in TRANSDERMAL DRUG DELIVERY SYSTEM

9. RESERVOIR (OR MEMBRANE) DEVICES These devices are used when the drug permeation rate is rapid and absorption should therefore be controlled by controlling drug release (R₁ < R₂). The drug is usually contained within the reservoir as a suspension in a liquid (such as silicone) or gel carrier. The rate-controlling thin polymeric membrane is made of olefinic polymers and copolymers, cellulosic esters, polyamides or PVC. When applied on the skin, the device shows a rapid release at first (initial burst effect) followed by a constant zero-order release as long as the solution inside the reservoir is saturated. 9 www.medacademy.org.in TRANSDERMAL DRUG DELIVERY SYSTEM

10. MIXED MONOLITHIC-RESERVOIR DEVICES A third type of system is basically a device having drug release kinetics intermediate between monolithic and reservoir systems. Here the drug-polymer matrix is layered by a rate-controlling membrane. The release is controlled initially by the membrane but as the drug gets depleted, the rate is controlled by the diffusion of the drug through a thicker layer of the polymer matrix. A major limitation of transdermal therapy is the poor skin penetrability of several drugs. This problem can be overcome by the use of penetration enhancers such as glycerol, propylene glycol, DMSO, SLS, etc. Drugs commonly presented in such systems are nitroglycerine , clonidine, scopolamine and estradiol . 10 www.medacademy.org.in TRANSDERMAL DRUG DELIVERY SYSTEM

11. Novel drug delivery system, volume 50, Y.W.Chien The theory & practice of industrial pharmacy, Leon Lachman , Herbert A.Lieberman , Joseph L.Kanig,3 rd edition. The Eastern pharmacist, november 1993. Sustained release drugs, V R.Gudsoorkar & D.Rambhau page 27-32 Biopharmaceuitics & pharmacokinetics, D M.Brahmankar & Sunil B. Jaiswal. Vyas S.P. , Khar R.K. ,Targeted & Controlled Drug Delivery, Novel Carrier Systems, CBS Publication ,2002 ,Page No.249-279 Malhotra M. and Jain N.K. Niosomes as Drug Carriers. Indian Drugs 1994, Page No: 81-86. Chandraprakash K.S., Udupa N., Umadevi P. and Pillai G.K. Pharmacokinetic evaluation of surfactant vesicles containing methotrexate in tumor bearing mice. Int. J. Pharma. 1990; R1-R3: 61. www.pharmainfo.net www.sciencedirect.com     11 www.medacademy.org.in REFERENCE

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