Mepron (Atovaquone) - Drug Interactions, Contraindications, Overdosage, etc

DRUG INTERACTIONS

Drug Interactions

Atovaquone is highly bound to plasma protein (>99.9%). Therefore, caution should be used when administering MEPRON concurrently with other highly plasma protein-bound drugs with narrow therapeutic indices, as competition for binding sites may occur. The extent of plasma protein binding of atovaquone in human plasma is not affected by the presence of therapeutic concentrations of phenytoin (15 mcg/mL), nor is the binding of phenytoin affected by the presence of atovaquone.

Rifampin

Coadministration of rifampin and MEPRON Suspension results in a significant decrease in average steady-state plasma atovaquone concentrations (see CLINICAL PHARMACOLOGY: Drug Interactions). Alternatives to rifampin should be considered during the course of PCP treatment with MEPRON.

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.

OVERDOSAGE

There is no known antidote for atovaquone, and it is currently unknown if atovaquone is dialyzable. The median lethal dose is higher than the maximum oral dose tested in mice and rats (1,825 mg/kg/day). Overdoses up to 31,500 mg of atovaquone have been reported. In 1 such patient who also took an unspecified dose of dapsone, methemoglobinemia occurred. Rash has also been reported after overdose.

CONTRAINDICATIONS

MEPRON Suspension is contraindicated for patients who develop or have a history of potentially life-threatening allergic reactions to any of the components of the formulation.