Adverse Drug Reactions

Question 1

Why is heparin initially prescribed alongside warfarin?

Answer 1

ironically warfarin has a pro-coagulant effect initially as well as taking a few days to become an anti-coagulant; thus
heparin should be prescribed alongside warfarin and continued until the
INR exceeds 2.

Question 2

Impact of K+ on digoxin effect

Answer 2

Low K+ augments digoxin effect
High K+ limit the effect

Digoxin competes with potassium at the myocyte Na+/K+ ATPase, limiting
Na+ influx.

Since Ca2+ outflow relies on Na+ influx, Ca2+ accumulates in the cell. This lengthens the action potential and slows the heart rate.

This summary is important because changes in serum K+ at the receptor can
compete with digoxin;

Question 3

Why should b-blockers and verapamil not be prescribed together?

Answer 3

profound hypotension and asystole
and the combination is
therefore avoided

(and strictly
contraindicated if IV verapamil)

Question 4

Alcohol + NSAIDs

Answer 4

GI bleeding

Question 5

Alcohol + warfarin

Answer 5

Acute alcohol (inhibitor): increased anticoagulant effect

Chronic alcohol (inducer): decreased anticoagulant effect

Question 6

Alcohol + monoamine oxidase inhibitors

Answer 6

Hypertensive crisis

Question 7

Alcohol + metronidazole

Answer 7

Sweating, flushing, nausea and
vomiting

Question 8

Alcohol + disulfiram

Answer 8

Sweating, flushing, nausea and
vomiting

Question 9

Alcohol + metformin

Answer 9

Lactic acidosis

Question 10

Alcohol + barbiturates

Answer 10

Sedation

Question 11

Alcohol + opioids

Answer 11

Sedation

Question 12

Alcohol + benzodiazepines

Answer 12

Sedation

Question 13

Treatment of antipsychotic induced Parkinsonism

Answer 13

Procyclidine hydrochloride