Chloroquine + Cimetidine = Precautionary

Effect on Concentration

Chloroquine
Increase
Applies within class?
No
Cimetidine
Decrease
Applies within class?
No

Pharmacologic Effects

Chloroquine
Effect
N/A
Applies within class?
No
Cimetidine
Effect
N/A
Applies within class?
No

Interaction History

N/A

Last Updated 15-May-2020

Summary

Cimetidine can inhibit the metabolism of chloroquine, increasing its plasma level. Concomitant use of cimetidine should be avoided.

Sources

Chloroquine elimination in humans: effect of low-dose cimetidine ^

Study Design

A controlled study was carried out in ten healthy, male volunteers to determine the effect of low-dose cimetidine on chloroquine elimination. The control group subjects received two tablets of chloroquine sulfate (300-mg base) only, while the test group subjects took 400-mg cimetidine at bedtime for four days prior to chloroquine (two tablets of chloroquine sulfate) administration and throughout the duration of the study. Blood samples, 5 mL, were collected periodically after chloroquine administration.

Study Results

The apparent oral clearance rate of chloroquine was reduced from 0.49 /- 0.04 L/d/kg in the control group to 0.23 /- 0.02 L/d/kg in the test group, and the elimination half-life was prolonged from 3.11 days in the control group to 4.62 days in the test group. The apparent volume of distribution at steady state was increased from 0.46 /- 0.07 L/kg in the control group to 0.72 /- 0.10 L/kg in the test group.

Study Conclusions

The author concluded that cimetidine impairs the elimination of chloroquine in healthy subjects.

References

Ette, EI. Chloroquine elimination in humans: effect of low-dose cimetidine. J Clin Pharmacol. 1987; 10: 813-6..