Drug metabolism and interactions

Question 1

Barbituates

Answer 1

induction

Question 2

Rifampicin

Answer 2

induction

Question 3

Griseofulvin

Answer 3

induction

Question 4

Phenytoin

Answer 4

induction

Question 5

Ethanol

Answer 5

induction

Question 6

Carbamazapine

Answer 6

autoinduction

Question 7

St John’s Wort

Answer 7

induction

Question 8

cimetidine

Answer 8

inhibition

Question 9

antifungals

Answer 9

inhibtion

Question 10

erythromycin

Answer 10

inhibtion

Question 11

ciclosporin

Answer 11

inhibition

Question 12

psoralen (grapefruit juice)

Answer 12

inhibition

Question 13

What drug should you not prescribe omeprazole with??

Answer 13

clopidogrel, metabolised by the same enzyme.

Question 14

Avoid aspirin and ? because of renal elimination??

Answer 14

methotrexate
NSAIDs reduce renal perfusion anyway
huge counselling point

Question 15

ACE-I and diuretics?

Answer 15

Careful with thiazides because they can cause hypokalaemia
Careful with severe hypotension
Take before bed

Question 16

diltiazem- do not prescribe with??

Answer 16

beta blockers, due to asystole risk

use a dihydropyridine instead

Question 17

why be cautious with warfarin?

Answer 17

avoid with enzyme inducers, this would lead to its failure in therapy
conversely, with inhibitors of cp450, it could lead to increased bleeding
could interact with erythromycin or ciprofloxacin
aspirin- increased bleeding

Question 18

veramapril and beta blockers?

Answer 18

no, no. risk of aystole

Question 19

which drugsshould you avoid with digoxin??

Answer 19

amiodarone and veramapril- toxicity risk

Question 20

be mindful of what with OTP?

Answer 20

risk of co-prescribing with induction effect-drugs. this would inc. risk of pregnancy