Lack of a pharmacokinetic interaction between azithromycin and chloroquine.

A study was conducted to investigate a possible pharmacokinetic interaction between azithromycin and chloroquine. Twenty-four subjects received azithromycin, 1,000 mg a day for three days, followed by a washout period, then azithromycin, 1,000 mg plus chloroquine 600 mg base on days 1 and 2, and azithromycin, 1,000 mg plus chloroquine 300 mg base on day 3 of the final period. A second group of 16 subjects received chloroquine, 600 mg base on days 1 and 2, then 300 mg base on day 3. Blood samples were obtained serially up to 624 hours after the day 3 dose in each period. Log transformed maximum concentration and area under the curve values of azithromycin and chloroquine were compared using 90% confidence intervals calculated from appropriate analysis of variance models. Ninety percent confidence intervals for all pharmacokinetic parameters were contained within the interval 80-125%, which indicates the absence of a clinically relevant pharmacokinetic interaction.