Industrial Pharmacy Lecture Notes PDF

COMPONENTS OF TDDS components of the transdermal drug delivery system include: Polymer matrix / Drug Reservoir Drug Permeation enhancers Pressure sensitive adhesive (PSA) Backing laminates Release liner Other excipients  POLYMER MATRIX Polymers are the backbone of TDDS...

COMPONENTS OF TDDS components of the transdermal drug delivery system include: Polymer matrix / Drug Reservoir Drug Permeation enhancers Pressure sensitive adhesive (PSA) Backing laminates Release liner Other excipients  POLYMER MATRIX Polymers are the backbone of TDDS, which control the release of the drug from the device. Polymer matrix can be prepared by dispersion of drug in liquid or solid state synthetic polymer base. Polymers used in TDDS should have biocompatibility and chemical compatibility with the drug and other components of the system such as penetration enhancer. Additionally they should provide consistent and effective delivery of a drug throughout the product's intended shelf life and should be of safe status EXAMPLES Natural Polymers: e.g. cellulose derivatives, zein, gelatin, shellac, waxes, gums, natural rubber and chitosan etc. Synthetic Elastomers: e.g. poly butadiene, hydrin rubber, polyisobutylene, silicon rubber, nitrile, acrylonitrile, neoprene, butyl rubber etc. Synthetic Polymers: e.g. polyvinyl alcohol, polyvinylchloride, polyethylene, polypropylene, polyacrylate, polyamide polyurea, polymethylmethacrylate ere. polyvinylpyrrolidone.  Drug The requirement of TDDS is that the drug possesses the right mix of physicochemical and biological properties for transdermal drug delivery. It is generally accepted that the best drug candidates for passive adhesive transdermal patches Permeation Enhancers These are the chemical compounds that increase permeability of stratum corneum so as to attain higher therapeutic levels of the drug candidate. Penetration enhancers interact with structural components of stratum corneum i.e., proteins or lipids. They alter the protein and lipid packaging of stratum corneum, thus chemically modifying the barrier functions leading to increased permeability  permeation enhancer should be pharmacologically inert, nontoxic, non irritating, nonallergic, odourless, tasteless, colourless, compatible with most drug and excipients, inexpensive, and have good solvent properties Different classes of penetration enhancers includes: 1. Alcohols and polyols (ethanol, propylene glycol). 2. Surfactants (Tween, Span, SLS). 3. Fatty acids (Oleic neid), 4. Amines and amides (N-methyl pyrrolidone). 5. Terpenes (limonene). 6. Sulfoxides (dimethyl sulfoxide) 7. Esters(isopropyl myristate). Mechanism of Permeation Permeation enhancers can enhance the skin permeability by a variety of mechanisms, including Interaction with intercellular lipids leading to disruption of their organization and increasing their fluidity. Extraction of lipids from the stratum corneum. Displacement of bound water. Release or let out of horny cells Enhancing solubility Increasing spliting into the stratum corneum.  Classification of Permeation enhancers:- a. Solvents. b. Surfactants. i) Anionic surfactants: Dioctyl sulphosuccinate, Sodium lauryl sulphate. ii) Non-ionic surfactants: Pluronic F127, Pluronic F68. iii) Bile salts : Sodium taurocholate, Sodium deoxycholate. c. Binary systems : Propylene glycol, oleic acid. d. Miscellaneous chemicals: Urea. Pressure sensitive adhesive (PSA) A PSA is a material that helps in maintaining contact between transdermal system and the skin surface. It should adhere with not more than applied finger pressure, be aggressively and permanently , exert a strong holding force. Additionally, it should be removable from the smooth surface without leaving any remains. Polyacrylates, polyisobutylene and silicon based adhesives are widely used in TDDSs.  Backing laminates While designing a backing layer, the consideration of chemical resistance of the material is most important. compatibility should also be considered because the prolonged contact between the backing layer and the excipients may cause the additives to leach out of the backing layer or may lead to diffusion of excipients, drug or penetration enhancer through the layer. √ Hold and protect the drug reservoir from exposure to atmosphere. √ Avoid loss of drug. √ Accept printing. √ High flexibility. Examples: vinyl polyethylene polyester films. Release liner During storage the patch is covered by a protective liner that is removed immediately before the application of the patch to skin. It is therefore regarded as a part of the primary packaging material rather than a part of dosage form for delivering the drug. However, as the liner is in intimate contact with the delivery system, it should comply with specific requirements regarding chemical inertness and permeation to the drug, penetration enhancer and water. Typically, release liner is composed of a base layer which may be non- occlusive (eg. paper fabric) or occlusive (e.g. polyethylene, polyvinylchloride) and a release coating layer made up of silicon or teflon. Other materials used for TDDS release liner include polyester foil and others.  Other excipients Various solvents such as chloroform, methanol, acetone, isopropanol and dichloromethane are used to prepare drug reservoir During storage the patch is covered by a protective liner that is removed and discharged immediately before the application of the patch to skin. It is therefore regarded as a part of the primary packaging material rather than a part of dosage form for delivering the drug.  Physico chemical evaluation Interaction studies Thickness of patch Weight uniformity Folding Percentage moisture content Water vapour permeability evaluation Flatness study Break test Drug content determination Content uniformity test  In vitro evaluation Invitro release studies In vitro skin permeation studies In vivo evaluation Animal studies Human models Skin irritation test Stability studies