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level: level 2

Questions and Answers List

III. Design features of transdermal drug delivery systems

level questions: level 2

QuestionAnswer
TDDSs are designed to support the passage of drug substances from the surface of the skin through its various layers and into the systemic circulation. True or FalseTrue
Transdermal drug delivery systems may be constructed of a number of layers, including:1) an occlusive backing membrane to protect the system from environmental entry and from loss of drug from the system or moisture from the skin 2) Drug reservoir or matrix system; store and release the drug at the skin-site; 3) a release liner, which is removed before application and enables drug release; 4) an adhesive layer to maintain contact with the skin after application.
TDDSs may be categorized into two types:1 Monolithic 2 Membrane-controlled systems
1 incorporate a drug matrix layer between backing and frontal layers. 2 designed to contain a drug reservoir, or pouch, usually in liquid or gel form, a rate-controlling membrane, and backing, adhesive, and protecting layers.1 Monolithic systems 2 Membrane-controlled transdermal systems
1 composed of a polymeric material in which the drug is dispersed. 2 controls the rate at which the drug is released for percutaneous absorption.1 drug-matrix layer 2 polymer matrix
With or without excess of drug In the preparation of monolithic systems, the1 __ and the 2 __ are 3 __1 drug 2 polymer 3 dissolved or blended together, cast as the matrix, and dried BCD
1 Membrane-controlled transdermal systems EXAMPLES 2 If the drug is delivered to the stratum corneum at a rate less than the absorption capacity, the __ is the controlling factor 3 if the drug is delivered to the skin area to saturation, the __ is the controlling factor 4 the rate of drug transport in all TDDSs, monolithic and membrane, is controlled by either __1 Transderm-Nitro, Transderm-Scop 2 device 3 skin 4 artificial or natural (skin) membranes.
Membrane-controlled systems have the advantage over monolithic systems in that as long as the drug solution in the reservoir remains __, the release rate of drug through the controlling membrane remains __1 saturated, constant.
must be occlusive to retain skin moisture hydrate the site of application, enabling increased drug penetration low moisture vapor transmission rate Transparent or pigmented films of polypropylene, polyethylene, polyolefin 2-3mm thickBacking Layer
must be pressure sensitive-> (ability to adhere to the skin with minimal pressure and remain in place for intended period to wear) non-irritating allow easy to peel off after use permit unimpeded drug flux to the skin compatible with all other components Tested for skin compatibility, test for irritation, sensitivity and toxicityAdhesive Layer
Commonly used Adhesive LayerPolybutyl acrylate
Two types of Adhesive layers1 Peripheral Adhesive 2 Face Adhesive
1 contains adhesive around the outer edge of TDDS, usually in wide strip surrounding the active drug portion. positioned in the back of the device & extending peripherally 2 covers the entire face of TDDS; positioned in the face of the device1 Peripheral Adhesive 2 Face Adhesive
Design objectives of TDDS1. Deliver the drug to the skin for percutaneous absorption at therapeutic levels at an optimal rate 2. Contain medicincal agents having the necessary physicochemical characteristics to release from the system and partition into the stratum corneum 3. Occlude the skin to ensure one way flux of the drug into the stratum corneum 4. Have a therapeutic advantage over other dosage forms and DDS 5. Not irritate or sensitize the skin 6. Adhere well to the patient's skin and have size, appearance, and site placement that encourage acceptance.