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
kinetic profiles for zero order drug
the curve is straight and constant
phases in drug metab
phase 1 - biotransformation - to make active molecule
phase 2- conjugation to make another charged molecule
important enzymes involeved in phase 1 metabolism
P450cyt enzymes
- has haem group
- metab wide range for diff molecule
- important site for drug interaction
what group can be added for conjugation in phase 2 metab
GSH, sulfate, glycine or glucronic acid
formula for loading dose
VdxC
is single dose or muiltiple doses better
muitlple cos it can increase plasma drug conc
which is better? continous infusion of 3 units of drug, injection of 3 units of drug once a day or injection of u=one unit of drugs 3 times a day
2nd option
pharmacogenetics
hoe genetic diff in metabolic pathways can affect individual responses to drugs
what is pharmacometabolomics
how drugs are metabolized
