Proguanil as chemoprophylaxis for malaria
Mode of action
- proguanil is converted to an active metabolite cycloguanil which inhibits the enzyme dihydrofolate reductase and interferes with the synthesis of folic acid. It acts as a suppressive and also as a causal prophylactic. Proguanil itself has a second mode of action, mediated by the parent drug rather than its metabolite, which produces synergy with atovaquone (see atovaquone plus proguanil).
Efficacy
- there are very few regions in the world where the local P. falciparum strains are fully sensitive to proguanil.
Prophylactic regimen
- adult dose 200 mg daily, starting 1 week before entering a malarious area, continuing throughout the time in the area and for 4 weeks after leaving the area.
Contraindications
- allergy to proguanil or to any ingredient of the tablets
Cautions
- Renal impairment.
- Pregnancy (folic acid 5mg daily is required for the length of time that proguanil is taken in pregnancy).
Interactions
- Drugs: May enhance the anticoagulant effect of warfarin
- Antifolate effect is increased when given with pyrimethamine
- Vaccines: None reported
Side-effects
Frequently reported are mild gastric intolerance and diarrhoea. Mouth ulcers and stomatitis occur occasionally, particularly when co-administered with chloroquine
Reference:
- Public Health England. Guidelines for malaria prevention in travellers from the UK 2022