[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Other antiprotozoals](https://durgical.com/en/pharmacology/classes/other-antiprotozoals/) › Atovaquone

# Atovaquone

## Other antiprotozoals?

Other antiprotozoals

Oral suspension for Pneumocystis pneumonia and prophylaxis when trimethoprim-sulfamethoxazole cannot be used; with azithromycin it treats babesiosis.

Updated Nov 1, 2026

## Quick facts

**Group**
[Other antiprotozoals](https://durgical.com/en/pharmacology/classes/other-antiprotozoals/)

**Target**
Mitochondrial cytochrome bc1 complex (complex III), Qo site, of the parasite or fungus

**Used for**
Pneumocystis jirovecii pneumonia · Babesiosis

**Key effects**
Nausea · Headache and dizziness · Rash

**Monitor**
Clinical response · Diarrhoea or vomiting · Rash

**ATC**
P01AX06

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

✂**Mitochondrial cytochrome bc1 complex (complex III), Qo site, of the parasite or fungus**Atovaquone

ⓘ The figure shows atovaquone at the Qo site of yeast (Saccharomyces cerevisiae) cytochrome bc1, a model for the Pneumocystis and Plasmodium complexes.

**Target in 3D:** Mitochondrial cytochrome bc1 complex (complex III), Qo site, of the parasite or fungus. PDB structure 4PD4 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/4PD4) · Drag to rotate · pinch to zoom

A hydroxynaphthoquinone that imitates ubiquinone (coenzyme Q). It binds the Qo site of cytochrome bc1 in the microorganism's mitochondria, stops electron transport and collapses the membrane potential. In Plasmodium this also cuts off pyrimidine synthesis, which depends on the bc1 complex. It is selective because the microbial cytochrome b differs from the human one. Single changes in cytochrome b cause resistance.

- Imitates ubiquinone
- Binds the Qo site of cytochrome bc1
- Electron transport and membrane potential collapse
- The microorganism runs out of energy and pyrimidines

## Indications

- Pneumocystis jirovecii pneumonia in teenagers and adults, and its prevention in people who cannot take another preventive drug (usually trimethoprim-sulfamethoxazole) [Pneumocystis pneumonia (PCP) →](https://durgical.com/en/conditions/pneumocystis-pneumonia/)
- Babesiosis, with azithromycin [Babesiosis →](https://durgical.com/en/conditions/babesiosis/)
- Toxoplasmosis, as an alternative regimen [Toxoplasmosis →](https://durgical.com/en/conditions/toxoplasmosis/)
- Malaria, only in fixed combination with proguanil (see atovaquone + proguanil) [Malaria →](https://durgical.com/en/conditions/malaria/)

## Adverse effects

### Common

- Nausea, vomiting and diarrhoea
- Headache and dizziness
- Rash
- Insomnia and anxiety
- Transient rises in liver enzymes or amylase

### Serious (rare, important)

- Allergic reactions: hives, swelling of the face or throat, trouble breathing, fever
- Treatment failure if absorption is poor (taken fasting, diarrhoea)

## Contraindications

- Hypersensitivity to atovaquone
- Caution: severe gut disorders or diarrhoea that limit absorption; liver disease

## Key interactions

**Rifampicin and rifabutin**
Lower atovaquone levels; the combination is avoided or monitored

**Tetracycline**
Lowers atovaquone concentrations

**Drugs highly bound to plasma proteins**
Atovaquone may compete for binding sites

## What is monitored

- Clinical response (fever, oxygen saturation, breathing) in Pneumocystis pneumonia
- Diarrhoea or vomiting that may reduce absorption
- Rash
- Liver function in liver disease

## Administration and safety

- Oral suspension, shaken gently before each use and measured with a proper dosing spoon or cup.
- Always given with meals (fat improves absorption).
- Vomiting and diarrhoea reduce absorption and can cause treatment failure: report them to the prescriber.

## Pregnancy and breastfeeding

Safety in pregnancy and breastfeeding still needs further study; it is used only when the prescriber judges the benefit worth it.

## Nursing care

- Give with food and check that meals are being eaten; fasting patients absorb it poorly.
- Record diarrhoea and vomiting and report them, since they can cause treatment failure.
- Watch breathing and oxygen saturation in pneumonia.
- Teaching: finish the course; tell the prescriber about rifampicin, rifabutin or antiretrovirals.

## Pharmacokinetics

**Absorption**
Slow and variable; much better with a fatty meal

**Distribution**
More than 99 % bound to plasma proteins; very low levels in cerebrospinal fluid

**Metabolism**
Double peaks in the blood after a dose suggest enterohepatic cycling

## Memory aid

«ATOVAQUONE = A TOtal VAcuum of QUinONE»: it takes the ubiquinone seat in complex III, and it needs FAT to get in.

## Test yourself

Think of the answer, then tap the question to see it.

## What is atovaquone's main indication?

Mild to moderate Pneumocystis jirovecii pneumonia and its prevention in people who cannot take trimethoprim-sulfamethoxazole.

## Why must the suspension be given with food?

Its absorption is slow and variable and much better with fat; low levels lead to treatment failure.

## Which drug is combined with atovaquone for babesiosis?

Azithromycin.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/atovaquone/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 3

- [Atovaquone + proguanil](https://durgical.com/en/pharmacology/atovaquone-proguanil/)
- [Sulfamethoxazole + trimethoprim (co-trimoxazole)](https://durgical.com/en/pharmacology/sulfamethoxazole-trimethoprim/)
- [Pyrimethamine](https://durgical.com/en/pharmacology/pyrimethamine/)

## Related conditions 4

- [Pneumocystis pneumonia (PCP)](https://durgical.com/en/conditions/pneumocystis-pneumonia/)
- [Babesiosis](https://durgical.com/en/conditions/babesiosis/)
- [Toxoplasmosis](https://durgical.com/en/conditions/toxoplasmosis/)
- [Malaria](https://durgical.com/en/conditions/malaria/)

[← Back to the class: Other antiprotozoals](https://durgical.com/en/pharmacology/classes/other-antiprotozoals/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Atovaquone: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a693003.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [Structural analysis of atovaquone-inhibited cytochrome bc1 complex reveals the molecular basis of antimalarial drug action.](https://www.rcsb.org/structure/4PD4) (RCSB Protein Data Bank (entry 4PD4), 2015).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/atovaquone/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/atovaquone/