Pharmacology: Subcutaneous and Transdermal Administration Flashcards
describe what subcutaneous administration involves
drug delivered by needle inserted into fatty tissue just beneath surface of the skin
how does subcutaneous drug route reach systemic circulation
by diffusion into either; capillaries, or lymphatic vessels
what are the advantages of subcutaneous drug route
absorption relatively slow due to poor vascular supply(can be good/bad), suitable for many protein drugs and oil-based drugs, can be used to introduce ‘depot’ of drug under skin released slowly into circulation, relatively simple and painless
what are the disadvantages of subcutaneous drug administration
injection volume limited
why is the skin an attractive route of drug administration for systemic effect
application is simple and non-sterile, potentially allows for steady-state plasma conc., avoids first pass metabolism, drug absorption can be terminated rapidly
what is the usual method of transdermal drug delivery
drug usually incorporated into an adhesive patch applied to the epidermis
how does drug absorption occur in transdermal drug delivery
by diffusion across cutaneous barrier, controlled by a drug release membrane
what drugs is transdermal drug delivery(TDD) most suitable for
low molecular weight, moderately lipophilic, potent or of relatively brief half-life
what are the advantages of transdermal drug delivery(TDD)
steady rate of drug delivery, decreased dosing frequency, avoid first-pass metabolism, rapid termination, user friendly, convenient, painless
what are the disadvantages of transdermal drug delivery(TDD)
relatively few drugs suitable for, allergies and cost
give 2 examples of drugs suitable for TDD
scopolamine, nicotine-GTN
describe what chemical enhancement can be used for transdermal drug delivery
enhancers interact with the lipid matrix of stratum corneum to increase permeability, mainly to drugs that also cross skin reasonably well
