pharmacokinetics 2 Flashcards
concentration of the drug depends on these 4 factors?
absorbtion, distribution, metabolism, exctretion
DMPK? stands for and what is it
Drug metabolism and pharmacokinetics - a step in early phase 1
Water components of the body?
plasma, interstitial, transcellular, intrecellular, lymph
Blood brain barrier what is it and what can pass
endothelial layer with tight junctions so impermeable to water soluble but not to lipid soluble
role of albumin in drug distribution
can bind to weak acid drugs, up to two molecules a time (1.2 mM) so that drug not available to bind to receptor. Can overcome by saturating all albumin but increases load of drug so danger
Liver role in metabolism?
step 1 - catabolic reaction to break down to an intermediate that can be dangerous?
step 2 - anabolic reactions to form inactive drug
Cytochrome p450? what is it and its role, genes
metabolic enzyme, microsomal (in cell) so drug has to cross PM, may require a transporter if polar
genes - CYP1,2,3
name 2 enzyme that metabolise in the liver?
alcohol dehydrogenase and MAO
What is the paracetamol intermediate and its issue?
NAPQI and is toxic to the liver
What is a pro drug?
drug that is only active when metabolised - can control its induction e.g. asprin is a pro drug of salicylic acid
Environmental (eating) that can effect metabolism?
grapefruit juice - inhibits cytochrome p450
brussel sprouts - increase its metabolic activity
why does diazepam stay in body longer?
can be stored in fat and can cross the BBB
main way and other ways drugs excreted ?
urine - 90%
GI
lungs
if reduce to half dose what are effect ?
half life stays the same but will leave body quicker
what should max rate you take in drugs not exceed?
metabolic rate
