Special Populations

Pediatrics: In a study of MEPRON Suspension in 27 HIV- infected, asymptomatic infants and children between 1 month and 13 years of age, the pharmacokinetics of atovaquone were age- dependent. These patients were dosed once daily with food for 12 days. The average steady- state plasma atovaquone concentrations in the 24 patients with available concentration data are shown in Table 1.

Hepatic/ Renal Impairment: The pharmacokinetics of atovaquone have not been studied in patients with hepatic or renal impairment.

Drug Interactions

Rifampin: In a study with 13 HIV- infected volunteers, the oral administration of rifampin 600 mg every 24 hours with MEPRON Suspension 750 mg every 12 hours resulted in a 52% ± 13% decrease in the average steady- state plasma atovaquone concentration and a 37% ± 42% increase in the average steady- state plasma rifampin concentration. The half- life of atovaquone decreased from 82 ± 36 hours when administered without rifampin to 50 ± 16 hours with rifampin.

Rifabutin, another rifamycin, is structurally similar to rifampin and may possibly have some of the same drug interactions as rifampin. No interaction trials have been conducted with MEPRON and rifabutin.

Trimethoprim/ Sulfamethoxazole (TMP- SMX): The possible interaction between atovaquone and TMP- SMX was evaluated in six HIV- infected adult volunteers as proof of a larger multiple- dose, dose- escalation, and chronic dosing study of MEPRON Suspension. In this crossover study, MEPRON Suspension 500 mg once daily, or TMP- SMX tablets (160 mg trimethoprim and 800 mg sulfamethoxazole) twice daily, or the combination were administered with food to achieve steady state. No difference was observed in the average steady- state plasma atovaquone concentration after coadministration with TMP- SMX. Coadministration of MEPRON with TMP- SMX resulted in a 17% and 8% decrease in average steady- state concentrations of trimethoprim and sulfamethoxazole in plasma, respectively. This effect is minor and would not be expected to produce clinically significant events.

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