Pharmacokinetics of Ethambutol under Fasting Conditions, with Food, and with Antacids

AUTOR(ES)
FONTE

American Society for Microbiology

RESUMO

Ethambutol (EMB) is the most frequent “fourth drug” used for the empiric treatment of Mycobacterium tuberculosis and a frequently used drug for infections caused by Mycobacterium avium complex. The pharmacokinetics of EMB in serum were studied with 14 healthy males and females in a randomized, four-period crossover study. Subjects ingested single doses of EMB of 25 mg/kg of body weight under fasting conditions twice, with a high-fat meal, and with aluminum-magnesium antacid. Serum was collected for 48 h and assayed by gas chromatography-mass spectrometry. Data were analyzed by noncompartmental methods and by a two-compartment pharmacokinetic model with zero-order absorption and first-order elimination. Both fasting conditions produced similar results: a mean (± standard deviation) EMB maximum concentration of drug in serum (Cmax) of 4.5 ± 1.0 μg/ml, time to maximum concentration of drug in serum (Tmax) of 2.5 ± 0.9 h, and area under the concentration-time curve from 0 h to infinity (AUC0–∞) of 28.9 ± 4.7 μg · h/ml. In the presence of antacids, subjects had a mean Cmax of 3.3 ± 0.5 μg/ml, Tmax of 2.9 ± 1.2 h, and AUC0–∞ of 27.5 ± 5.9 μg · h/ml. In the presence of the Food and Drug Administration high-fat meal, subjects had a mean Cmax of 3.8 ± 0.8 μg/ml, Tmax of 3.2 ± 1.3 h, and AUC0–∞ of 29.6 ± 4.7 μg · h/ml. These reductions in Cmax, delays in Tmax, and modest reductions in AUC0–∞ can be avoided by giving EMB on an empty stomach whenever possible.

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