Pyrimethamine

Pyrimethamine In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Interference with folate metabolism of the parasite and thereby prevents purine synthesis (and therefore DNA synthesis).

Uses of Pyrimethamine

• Treatment of infections caused by Toxoplasma gondii and Neospora caninum.
• Should not be used in pregnant or lactating animals without adequate folate supplementation.

Dose of Pyrimethamine in Dogs and Cats

Dogs, Cats:

• Toxoplasmosis/neosporosis: 1 mg/kg p.o. q24h or divided q12h for 4 weeks, alongside sulphonamides.

Side Effects of Pyrimethamine in Dogs and Cats

• Depression, anorexia and reversible bone marrow suppression (within 6 days of the start of therapy).
• Folate supplementation (5 mg/day) may prevent bone marrow suppression.

Contraindications of Pyrimethamine in Dogs and Cats

• No information is available.

Some Notes:

• Increased antifolate effect if given with phenytoin or sulphonamides.
• Folate supplementation for the host will reduce the efficacy of the drug if given concomitantly and should thus be given a few hours before pyrimethamine.