Drug/Drug interaction > 5

Question 1

Fibrinolytic drugs

Alteplase
Tenecteplase

Answer 1

Antiplatelet drugs / anticoagulants

ACE inhibitor

Question 2

Flucytosine

Answer 2

Anticancer drug
cytarabine

Question 3

Fluoroquinolones

Answer 3

Ciprofloxacin - theophylline
NSAIDs
Prednisolone

Question 4

H2 receptor antagonists
Ranitidine

Answer 4

No clinically significant drug interactions.

Question 5

Heparins

Answer 5

Antithrombotic drugs

Question 6

Insulin

Answer 6

systemic corticosteroids

Question 7

Iron

Answer 7

Reduces absorption of levothyroxine, bisphosphonates and tetracyclines

Question 8

Isoniazid

Answer 8

Acetaminophen
Carbamazepine
Valproate levels

Question 9

Isotretinoin

Answer 9

Vitamin A supplements
Increased risk of pseudotumor cerebri

Question 10

Laxatives

Bulk-forming
Osmotic
Stimulant

Answer 10

No clinically significant drug interactions

Effective of warfarin slightly increased when
taken with osmotic laxatives

Question 11

Lidocaine

Answer 11

epinephrine

Question 12

Linezolid

Answer 12

Increased risk of serotonin syndrome if taken with MAO inhibitors or other serotonergic drugs

Question 13

Macrolides

Answer 13

Clarithromycin / erythromycin

Warfarin; Statin

quinine, amiodarone, antipsychotics, SSRIs, fluoroquinolones etc.

Question 14

Metformin

Answer 14

Prednisolone and diuretics (loop/thiazide)

NSAIDs, ACE inhibitors etc.

Question 15

Methotrexate

Answer 15

Penicillins and NSAIDs

Trimethoprim and phenytoin

clozapine

Probenecid

Question 16

Metronidazole

Answer 16

Warfarin

Phenytoin

Lithium

Question 17

Naloxone

Answer 17

opioids

Question 18

Nicotine addiction
Bupropion

Answer 18

CYP 450 inhibitors- valproate

CYP 450 inducers –phenytoin, carbamazepine

Question 19

Nitrates

Answer 19

PDE5 inhibitors, such as sildenafil

Question 20

Nitrofurantoin

Answer 20

No clinically significant drug interactions

Question 21

NSAIDs

Answer 21

Aspirin, corticosteroids –GI ulceration

Anticoagulants, SSRIs- GI bleeding

Renal impairment – ACE
inhibitors, diuretics

increase bleeding risk of warfarin

Question 22

Ocular, artificial tears

Hypromellose
Carbomers
White soft paraffin

Answer 22

No clinically significant drug interactions.

Question 23

Estrogens

Progestogens

Answer 23

CYP 450 inducers – such as rifampin

Question 24

Opioids

Answer 24

benzodiazepines, antipsychotics, Z-drugs and TCA

Tramadol- SSRIs, TCAs

Question 25

Oxygen

Answer 25

No clinically significant drug interactions

Question 26

Penicillins

Answer 26

Methotrexate (renal)

Enhance anticoagulant effect of warfarin

Question 27

Phenytoin

Answer 27

reduces plasma concentration of warfarin, estrogens and progestogens

CYP inhibitors such as fluconazole, amiodarone and diltiazem.

Efficacy of phenytoin reduced by drugs that lower the seizure threshold (eg. SSRIs, antipsychotics, tramadol)

Question 28

PDE5 inhibitors
Sildenafil

Answer 28

Concurrent use with
nitrates produces
pronounced vasodilation / hypotension.

Question 29

Tadalafil

Answer 29

vasodilators such as
alpha-blockers and
calcium channel blocker

Question 30

Potassium – oral

Answer 30

potassium-elevating drugs / supplements
–such as ACE inhibitors
ARBs
potassium-sparing diuretic
IV potassium chloride
Aldosterone antagonists.

Question 31

Propofol

Answer 31

benzodiazepines and opioids

Question 32

Prostaglandin eye drops

Bimatoprost
Latanoprost

Answer 32

No clinically significant
drug interactions.

Question 33

Proton-pump inhibitors

Lansoprazole
Pantoprazole
Omeprazole

Answer 33

Omeprazole reduces antiplatelet effect of
clopidogrel

Question 34

Quinine

Answer 34

macrolides, fluoroquinolones, amiodarone,
antipsychotics and SSRIs.