Session 11.2: Pharmacokinetics 4

Question 1

how does CYP450 become induced

Answer 1

increased transctiption and translation…slower degragation (1-2 weeks)

Question 2

what happens when CYP450 becomes induced

Answer 2

elimination rate increases and plasma level of drug falls

Question 3

what is an example of CYP450

Answer 3

CBZ - anti epileptix drug..induced cytochrome p450 enzyme to control epilepsy

Question 4

what happens if another drug is metabolised at the same time

Answer 4

could inhibit CYP450 (competitive or non competitive) as one maybe metabolised by inhibited isoenzyme…so rate of elimination of other drug reduced
eg: grapefruit juice inhibits an isoenzyme which works to metabolise a drug to treat high BP so increases amount of drug absorbed into blood

Question 5

what can different efficacies of metabolism of codine cause

Answer 5

codeine into morphine
poor metaboliser = no pain relief as not form morphine
fast metaboliser = morphine intoxication, enhanced therapeutic effect

Question 6

what are the main processes involved of elimination in the kidney

Answer 6

glomerular filtration
active tubular secretion
passive tubular reabsorption

Question 7

how else can drugs be eliminated

Answer 7

bile, lung, sweat, tears, genital, saliva, breast milk

Question 8

how does drug get into glomular filtration

Answer 8

unbound drug enters via bowmans capsulse

Question 9

what happens during proximal tubular secretion

Answer 9

active secretion of drugs through OAT and OCT (low affinity, high capacity), carry ionised molecules out