Atovaquone (Wellvone) is an anti-protozoal drug, which is approved for the treatment of mild to moderate Pneumocystis pneumonia (PCP) in people who cannot take standard therapies such as co-trimoxazole (Septrin / Bactrim)^[1]. Atovaquone is less effective but better tolerated than co-trimoxazole^[2]. Atovaquone is also an alternative prophylaxis for PCP, being as effective as dapsone and pentamidine (Pentacarinat)^[3][4][5].

Atovaquone is also active against toxoplasmosis, particularly when combined with pyrimethamine (Daraprim) or sulfadiazene^[6][7].

When treating PCP, the recommended dose is 750mg twice daily times daily for between 14 and 21 days. It is also available on a named patient basis for the treatment of toxoplasmosis in people who are intolerant of or have not responded to standard treatments. Tablets used during atovaquone trials were poorly absorbed and less effective than the suspension, thus the tablets are no longer available^[8].

Preliminary results indicate that atovaquone may decrease diarrhoea and increase weight in people with microsporidiosis, although it does not eradicate the organisms from the gut^[9].

Side-effects can include rash, diarrhoea, nausea and fever.

Taking the anti-tuberculosis drug rifampicin (Rifadin / Rimactane) at the same time as atovaquone dramatically reduces blood levels of atovaquone, as does the anti-nausea drug metoclopramide (Maxolon). The protease inhibitors atazanavir (Reyataz), lopinavir, ritonavir (Norvir) and tipranavir (Aptivus) may reduce the levels of atovaquone, so that a dose increase may be necessary.