ATOVAQUONE - A NEW ANTIPNEUMOCYSTIS AGENT

The mechanism of action, pharmacokinetics and pharmacodynamics, clinic al efficacy, adverse effects, and dosage of atovaquone in the manageme nt of mild to moderate Pneumocystis carinii pneumonia (PCP) are review ed. Atovaquone has a novel mechanism of action that has been hypothesi zed to result in microbicidal rather than microbistatic activity again st Pnemocystis carinii. Absorption of the drug is significantly enhanc ed by the presence of food, particularly food with a high fat content. In comparative trials, atovaquone was slightly less effective than tr imethoprim-sulfamethoxazole and as effective as pentamidine isethionat e in treating mild to moderate PCP. Atovaquone is associated with a lo wer incidence of treatment-limiting adverse reactions than are trimeth oprim-sulfamethoxazole and pentamidine isethionate. The most commonly occurring adverse effect in patients receiving atovaquone is rash, and the drug does not appear to cause bone marrow suppression. The FDA-ap proved dosage regimen for atovaquone in treating mild to moderate PCP is 750 mg (three 250-mg tablets) administered orally three times daily with food for 21 days. Atovaquone may be considered a first-line trea tment for patients with the acquired immunodeficiency syndrome who hav e mild to moderate PCP and have demonstrated an intolerance to trimeth oprim-sulfamethoxazole.