Drug/Drug interaction > 3

Question 1

Bisphosphonates

Answer 1

antacids, iron

Question 2

Calcium

Answer 2

reduces absorption of
bisphosphonates, tetracyclines and
levothyroxine

Question 3

Calcium

Answer 3

reduce absorption of bisphosphonates,
tetracyclines and
levothyroxine

Avoid with sodium
bicarbonate

Question 4

Calcium channel
blockers

Answer 4

Avoid with beta-blockers

Question 5

Carbamazepine

Answer 5

reduce concentration of drugs such as warfarin,
progestogens and
estrogens

lower the seizure threshold – such as TCAs, SSRIs and tramadol

reduce efficacy of anticonvulsant
medicines.

Question 6

Cephalosporins

Carbapenems

Answer 6

Enhance the anticoagulant effect of warfarin

Increase nephrotoxicity of
aminoglycosides

reduce efficacy of valproate

Question 7

Clopidogrel

Answer 7

CYP 450 inhibitors block
its activation –

omeprazole, erythromycin, antifungals, SSRIs etc.

Risk of bleeding increases with antiplatelet, anticoagulant
drugs and NSAIDs

Question 8

Corticosteroids

Systemic
Prednisolone
Hydrocortisone
Dexamethasone

Answer 8

NSAIDs increase risk of
peptic ulceration /
bleeding

Risk of hypokalemia
when taken with B2-
agonists, loop or thiazide
diuretics

Efficacy reduced by CYP
inducers such as
phenytoin and rifampin.

reduce immune response to vaccines.

Question 9

As these drugs are
inhaled, there are no
clinically significant drug
interactions

Answer 9

Corticosteroids

Inhaled
Beclometasone
Budesonide
Fluticasone

Question 10

Corticosteroids Topical- No significant drug interactions

Answer 10

Hydrocortisone
Betamethasone