Pharmacokinetics Flashcards
What do drug effects depend on
mechanism of action, physiochemical properties,
What does the concentration of drug when given depend on
absorption, distribution, metabolism, excretion
What is pharmacokinetics
branch of pharmacology concerned with the movement of drugs in the body
What does drug metabolism and pharmacokinetics reduce when its integrated into drug development
attrition
How are drugs absorbed and distributed through the body
diffusion and transfer through bloodstream
What does the movement of drugs between compartments usually involve
penetration of lipid diffusion barriers
What molecules diffuse freely through lipids
non polar uncharged molecules
What does diffusion of drugs through lipids increase
rate of absorption from gut, penetration into brain, renal elimination
What is the most important determinant of pharmacokinetic characteristics of a drug
lipid solubility
What influences drug absorption in the body
access to desired site of action
How are oral or rectal drugs excreted
faeces
How are inhaled drugs excreted
expired air
What factors affect absorption of drugs
method of administration, molecular weight, lipid solubility, pH and ionisation
What does molecular weight of drugs effect
rate of diffusion
What does lipid solubility of drugs effect
ability to cross lipid membrane by diffusion
What happens to weak acids at low pH
un-ionized
How can pH affect drug movement
affect the steady state distribution of drugs between aqueous compartments
What do basic pH environments favour
dissociation of acids
What can weak acids become trapped in in basic environments
basic compartments e.g. renal tubules
What is the effect of increasing plasma pH on weakly acidic drugs
causes extraction from CNS into plasma where they get ‘trapped’
What is the effect of trapping weakly acidic drugs
neurotoxicity
True or False - carrier mediated transport can affect drug absorption
true
What are genetic variants of organic cation transporter 1 associated with
different responses to metformin in healthy humans
