Chloroquine + Antacids = Precautionary

Effect on Concentration

Chloroquine
Decrease
Applies within class?
No
Antacids
No change
Applies within class?
No

Pharmacologic Effects

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

Interaction History

N/A

Last Updated 15-May-2020

Summary

Antacids and kaolin can reduce absorption of chloroquine; an interval of at least 4 hours between intake of these agents and chloroquine should be observed.

Sources

Adsorption of paracetamol and chloroquine phosphate by some antacids ^

Study Design

An in vitro study indicated that certain antacids and adsorbents may decrease the oral availability of the two widely used antimalarial agents chloroquine and pyrimethamine. To determine if this data was applicable to the clinical (in vivo) situation, plasma levels of one of the antimalarial agents (chloroquine) were followed in six African--Arab volunteers both when given alone and when taken with separate doses of two of the implicated interactants (magnesium trisilicate and kaolin).

Study Results

Chloroquine area under the plasma concentration-time curve data were decreased by both magnesium trisilicate (18.2) and kaolin (28.6).

Study Conclusions

Author concluded that in order to avoid loss of drug, chloroquine should not be taken with gastrointestinal medications of this type or that their administration should be separated by at least 4 h to reduce the risk of them interacting in the gut, thus preventing drug adsorption to the antacids/adsorbents, and loss of systemic availability.

References

Iwuagwu, MA, Aloko, KS. Adsorption of paracetamol and chloroquine phosphate by some antacids. J Pharm Pharmacol. 1992; 8: 655-8..