Zidovudine

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

Overview

• Competitive inhibition of reverse transcriptase.
• Requires activation to the 5’-triphosphate form by cellular kinases.

Uses of Zidovudine

• Treatment of FIV-positive cats.

Dose of Zidovudine in Dogs and Cats

Cats:

• FIV infection: 5 mg/kg daily p.o., s.c. q12h.
• The dose may be increased to 10 mg/kg q12h.

Dogs:

• Not applicable.

Side Effects of Zidovudine in Dogs and Cats

• Hepatotoxicity and severe anaemia can occur at doses higher than those recommended.
• Long-term adverse effects of lower doses have not been ascertained.

Contraindications of Zidovudine in Dogs and Cats

• Animals that are severely anaemic or leucopenic should not be given this drug.

Some Notes:

• In cats without clinical signs, it may postpone the onset of symptoms.
• For cats displaying clinical signs, it may enhance recovery when used alongside other treatments.
• In human medicine, it is employed alongside other nucleoside reverse transcriptase inhibitors like abacavir, didanosine, lamivudine, stavudine, tenofovir, and zalcitabine.
• Typically, two of these drugs are paired with either a non-nucleotide reverse transcriptase inhibitor or a protease inhibitor to prevent drug resistance in HIV-positive individuals.
• However, protease inhibitors used in humans have limited effectiveness against FIV, hindering this strategy for FIV-infected cats in the clinical phase.
• Nonetheless, combining lamivudine (3TC) with zidovudine appears to be more effective than using zidovudine alone in reducing viral load and increasing CD4/CD8 ratios in cats over one year.
• Combining zidovudine with interferon does not enhance these parameters.
• These findings are based on studies involving small numbers of cats, so haematological monitoring is advised.