Common Incompatibilities

Question 1

alcohol + sedative-hypnotics,
opioid analgesics,
TCAs,
antihistamines

Answer 1

additive CNS depression,
sedation,
ataxia,
increased risk of accidents

Question 2

alcohol + ______ = additive CNS depression,
sedation,
ataxia,
increased risk of accidents

Answer 2

sedative-hypnotics,
opioid analgesics,
TCAs,
antihistamines

Question 3

aminoglycosides + loop diuretics

Answer 3

enhanced ototoxicity

Question 4

antacids + iron supplements,
fluoroquinolones,
ketoconazole,
tetracyclines

Answer 4

decreased gut absorption

Question 5

antibiotics + estrogens, including oral

contraceptives

Answer 5

many antibiotics lower estrogen levels

and reduce contraceptive effectiveness

Question 6

antihistamines (H1-blockers) + antimuscarinics,

sedatives

Answer 6

additive effects with the drugs involved

Question 7

antimuscarinic drugs + drugs absorbed from small intestine

Answer 7

slower onset of effect

Question 8

barbiturates (esp. 
phenobarbital) + azoles,
CCBs,
propranolol,
quinidine,
steroids,
warfarin,
and many other drugs metabolized in 
the liver

Answer 8

increased clearance of the affected

drugs

Question 9

beta-blockers + insulin

Answer 9

masking of symptoms of hypoglycemia

Question 10

beta-blockers + prazosin

Answer 10

increased “first-dose” syncope

Question 11

bile acid-binding resins + acetaminophen,
digitalis,
thiazides,
thyroxine

Answer 11

reduced absorption of the affected

drugs

Question 12

carbamazepine +
doxycycline,
estrogen,
haloperidol,
theophylline,
warfarin

Answer 12

reduced effect of the affected drugs

Question 13

cimetidine +
benzodiazepines,
lidocaine,
phenytoin,
quinidine,
theophylline,
warfarin

Answer 13

increased effect

Question 14

disulfiram,
metronidazole,
certain cephalosporins + ethanol

Answer 14

increased hangover effect

Question 15

erythromycin + cisapride,
quinidine,
sildenafil,
theophylline

Answer 15

risk of toxicity

Question 16

ketoconazole and other  +
azoles
benzodiazepines,
cisapride,
cyclosporine,
fluoxetine,
lovastatin,
omeprazole,
quinidine,
tolbutamide,
warfarin

Answer 16

risk of toxicity

Question 17

MAOIs + catecholamine releasers

amphetamine, ephedrine

Answer 17

increased NE in the sympathetic nerve

endings

Question 18

MAOIs + tyramine-containing food and

beverages

Answer 18

hypertensive crisis

Question 19

NSAIDs + anticoagulants

Answer 19

increased bleeding tendency

Question 20

NSAIDs + ACE inhibitors

Answer 20

decreased antihypertensive efficacy

Question 21

NSAIDs + loop diuretics,

thiazides

Answer 21

reduced diuretic efficacy

Question 22

phenytoin + doxycycline,
methadone,
quinidine,
steroids,
verapamil

Answer 22

increased metabolism of drugs involved

Question 23

quinidine + digoxin

Answer 23

increased digoxin levels

Question 24

rifampicin +
azole antifungals,
corticosteroids,
methadone,
theophylline,
tolbutamide

Answer 24

decreased efficacy of the drugs involved

Question 25

salicylates + corticosteroids

Answer 25

additive toxicity to gastric mucosa

Question 26

salicylates + heparin,

warfarin

Answer 26

increased bleeding tendency

Question 27

salicylates + methotrexate

Answer 27

decreased clearance of drug involved

Question 28

salicylates + sulfinpyrazone

Answer 28

decreased uricosuric effect

Question 29

SSRIs +
MAOIs,
meperidine,
TCAs

Answer 29

Serotonin syndrome

Question 30

thiazides + digitalis

Answer 30

increased risk of digitalis toxicity

Question 31

thiazides + lithium

Answer 31

increased plasma levels of lithium

Question 32

warfarin +
cimetidine,
erythromycin,
lovastatin,
metronidazole

Answer 32

increased anticoagulant activity

Question 33

warfarin + anabolic steroids,
aspirin,
NSAIDs,
quinidine,
thyroxine

Answer 33

increased anticoagulant effect

Question 34

warfarin + barbiturates,
carbamazepine,
phenytoin,
rifampicin

Answer 34

decreased anticoagulant effect