9: Transdermal Delivery Systems Flashcards
what is the difference between TDS and topical
TDS get into systemic circulation for widespread effects
topical = local effect only
list 3 advantages of TDS drugs
- avoids deactivation
- noninvasive
- less frequent application
- avoids interactions
- effective for drugs that cause nausea
- patient compliance
- ease of removal
- controlled release property
- easily recognizable in emergency
what are some limitations of TDS
- absorption of drugs from skin may be limited
- dermatitis at site
- lag time
the stratum corneum is made up of _____ ____ cells separated from each other by a _________
protein rich cells
thin layer of intercellular lipids
3 ways a drug can pass through the stratum corneum
- paracellular
- transcellular
- through hair follicles and sweat glands
what is the most important mechanism of percutaneous absorption
diffusion
what are the 3 characteristics that makes the best drug for TDS
low MW and melting point, moderate lipophilicity and excretion
3 parts of a TDS
backing membrane
adhesive layer
release liner
the backing membrane of a TDS must be
occlusive
what can the backing membrane be made of
propylene, polyethylene, and polyolefins
where is the drug contained layer located
between the backing membrane and adhesive layer
what is commonly used for the adhesive layer
polybutyl acrylate
which system is zero order release
- membrane controlled system
- monolithic system
membrane release system
if a membrane controlled patch is used right after manufacturing there will be a ________
if it is expired there may be a _________
lay time
dose dumping
what is the only factor we can change of a TDS for release
concentration of drug in reservor