Atovaquone

How it works

It selectively inhibits the parasite cytochrome bc1 complex of the mitochondrial electron transport chain, disrupting pyrimidine biosynthesis and energy production.

Prescribing in practice

• Absorption is poor and highly dependent on fat, so atovaquone must be taken with a fatty meal to achieve adequate plasma concentrations and treatment efficacy, particularly important in patients with diarrhoea or malabsorption.
• It is generally less effective than co-trimoxazole for Pneumocystis pneumonia, so it is reserved for those intolerant of first-line therapy.
• Concurrent rifampicin and certain other agents can substantially lower atovaquone levels and reduce efficacy.

Monitoring

Monitor clinical response and tolerability, with attention to whether the drug is being taken with food to ensure adequate absorption.

Counselling the patient

• Always take this medicine with food, ideally something containing fat, to help it work.
• Continue prophylaxis for as long as advised even when you feel well.
• Report persistent diarrhoea or vomiting, which may reduce how well the drug is absorbed.

Evidence & guidelines

Atovaquone is recommended in UK guidance as an alternative agent for Pneumocystis jirovecii pneumonia prophylaxis and treatment in patients intolerant of co-trimoxazole.