Chapter 4 - Drug Absorption Flashcards
true or false
ONLY free drug can get distributed to the target site/other tissues
true
3 routes of administration
intravascular
extravascular
topical
how can extravascular drug administration be further divided?
parenteral and non-parenteral
name the extravascular parenteral routes
IM and SUBQ
NOT IV!!!!!!!! IV is intravascular
true or false
extravascular parenteral is preferred over extravascular non-parenteral
FALSE
non-parenteral is preferred bc less expensive painless, can self-medicate, and more likely to comply
what is the first layer of the skin? is it more or less lipophilic than the dermis?
stratum corneum
3-5x more lipophilic than the dermis(hard to penetrate!)
compare the surface area for topical absorption vs through the small intestine
skin - 1.73 meters squares
small intestines - 150-200 meters squared
mechanism of topical absorption through the skin
passive diffusion
the stratum corneum can be considered ____ phase
what is continuous?
2 phase lipid/protein
lipid is continuous
5 DOSAGE FORM factors that affect topical absorption through the skin
-drug’s affinity for the vehicle
-surface area of the film
-thickness of the film
-permeation enhancers
-concentration of drug in the delivery system
true or false
the larger the surface area of the patch, the quicker the absorption rate
true
true or false
the thicker the film, the faster the drug will permeate
FALSE
if thinner, will permeate faster
true or false
we do not want the drug to have a very high affinity to the vehicle for topical absorption
true
otherwise will take forever to come out and absorb through the skin
rate limiting layer of skin permeation
the stratum corneum
true or false
skin permeation is an active process
FALSE - passive diffusion
*****4 advantages of topical absorption
-no 1st pass I
-long acting
-no degradation in GI
-can deliver potent lipophilic drugs with a short half life ***
what kinetics do we want for transdermal delivery
zero order
***major advantage of transdermal delivery is the type of drug we can deliver —-
potent, lipophilic drug with a short half life
if given orally - would need very frequent dosing! transdermal is a very good way to administer it - provides a long duration of action for it!!!!!!!!!!!
3 disadvantages of topical/transdermal absorption
metabolism of drug in skin
binding to the epidermis
blood supply
True or false
dosage form does not have an impact on bioavailability
FALSE
impacts absorption and thus impacts bioavailability
true or false
if a drug is rapidly absorbed, it is less likely to degrade in the GI fluids
TRUE - bc not there for that long
true or false
a disadvantage of rapid oral drug absorption is that it increases variability
FALSE - actually decreases variability
3 major factors that influence the release of the drug from the dosage form administered orally
physiochemical properties of:
-the drug
-the dosage form
-human body variations
true or false
the human body variations ONLY AT THE SITE OF ABSORPTION can affect absorption
FALSE - also at the site of administration