Metabolism of Drugs - Exam 3 Flashcards
definition of metabolism of drugs
chemical alteration of the drug molecule by the cells of the animal
bioinactivation
detoxification, most common, parent drug -> inactivate
bioactivation
lethal synthesis, “prodrug” -> active drug
liver as a site of biotransformation
most common site, sER, hepatocyte cytoplasm, mitochondria, lysosomes, nuclear envelope, plasma membrane
other tissue sites of biotransformation
nervous tissue, kidney, GI epithelium, lungs, skin, plasma
example of active drug -> active metabolite
aspirin converted to salicylic acid
example of inactive drug -> active metabolite
cortisone -> cortisol
prenisone -> prednisolone
example of nontoxic drug -> toxic metabolite
parathion -> paroxon
ethylene glycol -> glyoxylic acid “lethal transformation”
antifreeze toxicity is an example of ________ ; includes what 2 toxic metabolites
biotransformation; glycoaldehyde & glycoxylate
microsomal enzymes
non-specific, large groupings of enzymes, cause oxidation, reduction, hydrolysis, & conjugation to glucuronic acid
T/F: enzymatic reactions are saturable
true
T/F: enzymes can inhibited or induced by drugs
true
Phase I reactions include
oxidation, reduction, hydrolysis; non-synthetic
Phase II reactions include
conjugation; synthetic
definition of oxidation
loss of one or more electrons by a substance, gain O2, remove H+; most common biotransformation reaction
definition of reduction
gain of one or more electrons by a substance, gain H+, remove O2
definition of hydrolysis
splitting of a molecule into fragments by the addition of H2O
microsomal oxidation phase I
sER
nonmicrosomal oxidation phase I
cytoplasm, mitochondria
microsomal reduction phase I
reduction of chloramphenicol
nonmicrosomal reduction phase I
aldehyde reduction of chloral hydrate
lipid soluble drugs must go to phase ____ prior to excretion
II
conjugation reactions phase II
combination of a drug or its metabolite with an endogenous substance
conjugation is deficient in
neonates & cats