L5 - therapeutic conc Flashcards
what are ADME pricniples
absorption, distribution, metabolism, excretion
what are the phases uptil the Cmax and Tmax
absorption and distribution
what are the phases after the Cmax
and Tmax
metab and excret
routes of entry
absorption fromGIT
- injection
- inhalation
- absorp from skin
- intramuscular
what happens when a drug is absorbed in GIT
- this mean via liver
- metab can happen in gut or liver will alter plasma conc achieved
- this is first pass metab
what happens when a drug is absorbed in GIT
- this mean via liver
- metab can happen in gut or liver will alter plasma conc achieved
- this is first pass metab
factors affecting the distribution of the drug
membrane permeability
- protein binding
- pH partioning
- accul in adipose tissue
what is Volume distrib (Vd)
vol of fluid containing total amount of drug at the same conc as present in plasma
formula for Vd
dose of drug(mg)/ Cp (plasma conc of drug, mg/L)
the relationship between Vd and Cp
Vd=Cp
relationship between Vd and Cp if the drug is in the tissues
Cp decreases due to less drug in plasma
and Vd increase due to more being distributed
sites for drig metab
liver - has large SA due to sinusoids, dual blood supply and there’s first pass metab
lungs - when there is all of CO and large SA due to exchange function
kidneys - plasma filtered and drug as well (most less < protein weight and size ) for excretion
what is clearance
vol of body fluid cleared of a substance per item
clearance formula
C=Cmax e^-kt
kinetic profiles for first order drug
the curve goes steep then fall flat
half life = ln(2)/k
