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Malarone (Atovaquone / Proguanil Hydrochloride) - Drug Interactions, Contraindications, Overdosage, etc

 
 



DRUG INTERACTIONS

Rifampin/Rifabutin

Concomitant administration of rifampin or rifabutin is known to reduce atovaquone concentrations [see Clinical Pharmacology]. The concomitant administration of MALARONE and rifampin or rifabutin is not recommended.

Anticoagulants

Proguanil may potentiate the anticoagulant effect of warfarin and other coumarin-based anticoagulants. The mechanism of this potential drug interaction has not been established. Caution is advised when initiating or withdrawing malaria prophylaxis or treatment with MALARONE in patients on continuous treatment with coumarin-based anticoagulants. When these products are administered concomitantly, coagulation tests should be closely monitored.

Tetracycline

Concomitant treatment with tetracycline has been associated with a reduction in plasma concentrations of atovaquone [see Clinical Pharmacology]. Parasitemia should be closely monitored in patients receiving tetracycline.

Metoclopramide

While antiemetics may be indicated for patients receiving MALARONE, metoclopramide may reduce the bioavailability of atovaquone and should be used only if other antiemetics are not available [see Clinical Pharmacology].

Indinavir

Concomitant administration of atovaquone and indinavir did not result in any change in the steady‑state AUC and Cmax of indinavir but resulted in a decrease in the Ctrough of indinavir [see Clinical Pharmacology]. Caution should be exercised when prescribing atovaquone with indinavir due to the decrease in trough concentrations of indinavir.

OVERDOSAGE

There is no information on overdoses of MALARONE substantially higher than the doses recommended for treatment.

There is no known antidote for atovaquone, and it is currently unknown if atovaquone is dialyzable. Overdoses up to 31,500 mg of atovaquone have been reported. In one such patient who also took an unspecified dose of dapsone, methemoglobinemia occurred. Rash has also been reported after overdose.

Overdoses of proguanil hydrochloride as large as 1,500 mg have been followed by complete recovery, and doses as high as 700 mg twice daily have been taken for over 2 weeks without serious toxicity. Adverse experiences occasionally associated with proguanil hydrochloride doses of 100 to 200 mg/day, such as epigastric discomfort and vomiting, would be likely to occur with overdose. There are also reports of reversible hair loss and scaling of the skin on the palms and/or soles, reversible aphthous ulceration, and hematologic side effects.

CONTRAINDICATIONS

Hypersensitivity

MALARONE is contraindicated in individuals with known hypersensitivity reactions (e.g., anaphylaxis, erythema multiforme or Stevens-Johnson syndrome, angioedema, vasculitis) to atovaquone or proguanil hydrochloride or any component of the formulation.

Severe Renal Impairment

MALARONE is contraindicated for prophylaxis of P. falciparum malaria in patients with severe renal impairment (creatinine clearance <30 mL/min) because of pancytopenia in patients with severe renal impairment treated with proguanil [see Use in Specific Populations and Clinical Pharmacology].

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