Dosages of Antiviral Drugs
Drug | Preparation | Species, Dose, Route, and Frequency | Indication | Notes |
|---|---|---|---|---|
Idoxuridine | 0.1% ophthalmic solution or 0.5% ophthalmic ointment | Cats, dogs, horses: 1 drop or ¼-inch strip in affected eye, every 2–3 h for 48 h, followed by every 4–6 h until one week beyond resolution of clinical signs | Ocular herpesvirus (FHV-1, CHV-1, EHV-2) infection | No longer commercially available in the US but may be prepared by compounding pharmacies Not approved for use in food animals Potential teratogen: caution for use in pregnant animals; women who are pregnant should avoid handling |
Trifluridine | 1% ophthalmic solution | Cats, dogs: 1 drop, OU, every 2 h for 2 days, then 3–8 times daily until 1 week beyond resolution of clinical signs; do not use more than 3 weeks to avoid corneal toxicity | Ocular herpesvirus (FHV-1, CHV-1) | Not approved for use in food animals Caution in patients with glaucoma; may increase intraocular pressure Women who are pregnant should be cautious when handling Less well tolerated in cats due to ocular discomfort (stinging) on administration |
Vidarabine | 3% ophthalmic ointment | 0.4- to 1-cm strip, OU, every 5–6 h until one week beyond resolution of clinical signs | Ocular herpesvirus (FHV-1) | No longer commercially available in the US but may be prepared by compounding pharmacies Not approved for use in food animals |
Cidofovir | 0.5% ophthalmic solution (compounded from 75 mg/mL injection) | Cats: 1 drop, OU, every 12 h for 5 days | Ocular herpesvirus (FHV-1) | Not approved for use in food animals Potential teratogen: caution for use in pregnant animals; women who are pregnant should avoid handling or wear protective apparel when handling |
Acyclovir | 200-mg capsules, 400- or 800-mg tablets, 200 mg/5 mL oral suspension; 50 mg/mL injectable solution or powder for reconstitution; 5% topical ointment | Dogs: 10 mg/kg, PO, every 6 h for 5 days (neonatal CHV-1); 20 mg/kg, IV, every 8 h for 5 days (prophylaxis of canine parvovirus infection) Horses: 10 mg/kg, IV slowly over 1 h, every 12 h (EHV) Birds: 80 mg/kg, PO, every 8 h for 7–14 days (Pacheco's disease) Cats: Contraindicated due to risk of myelosuppression and nephrotoxicity | CHV-1, prophylaxis of canine parvovirus, EHV, Pacheco's disease | Not approved for use in food animals Poor oral bioavailability in horses; oral administration not recommended Caution in patients with renal disease and with coadministration potentially nephrotoxic drugs |
Valacyclovir | 1-g and 500-mg tablets | Horses: 27–40 mg/kg, PO, every 8 h for 2 days, then 18–20 mg/kg, PO, every 12 h for 1–2 weeks Cats: Contraindicated due to hepatic, renal, and bone marrow toxicity | EHM, EHV-1, EHV-3 | Not approved for use in food animals Contraindicated in cats Caution in patients with renal disease and with coadministration of nephrotoxic drugs |
Ganciclovir | 500 mg/vial powder, 0.15% ophthalmic solution | Horses: 2.5 mg/kg, as slow IV bolus, every 8 h for 1 day, then 2.5 mg/kg, as slow IV bolus, every 12 h for maintenancea,b Dogs: 1 drop, in affected eye, 5 times daily until ulcer resolution; then 1 drop, in affected eye, 3 times daily for 7 days Cats: 1 drop, in affected eye, every 6 h | Feline herpes keratitis, EHM, ocular CHV-1 | Not approved for use in food animals Potential teratogen: caution for use in pregnant animals; women who are pregnant should avoid handling |
Famciclovir | 125-, 250- and 500- mg tablets | 90 mg/kg, PO, every 8–12 h until 1 week beyond resolution of clinical signsc | FHV-1 | Not approved for use in food animals |
Zidovudine | 10 mg/mL syrup; 10 mg/mL injection; 300-mg tablets; 100-mg capsules | Cats: 5–10 mg/kg, PO or SC, every 12 h | FIV, FeLV | Not approved for use in food animals Caution in animals with bone marrow suppression; monitor for development of anemia in treated animals, and discontinue use if hematocrit is < 20% |
Rimantadine | 100-mg tablets | Horses: 30 mg/kg, PO, every 12 h | Equine influenza | Prohibited for use in poultry in the US Not approved for use in food animals |
Interferon alfa-2 | 3 × 106 IU/vial; 30-60 IU/mL oral solution (compounded from commercially available injectable solution) | Cats: 60 IU/cat, PO or buccally once daily, treated 7 days on, 7 days off | FeLV | No oral formulation commercially available in the US, but may be prepared by compounding pharmacies Not approved for use in food animals Do not vaccinate animals receiving interferon-alfa |
Oseltamivir | 30-, 45-, and 75-mg capsules; 30 mg/5 mL oral suspension reconstituted from powder | Horses: 2 mg/kg, PO, every 12 h for 5 days Dogs: 2 mg/kg, PO, every 12 h for 5 days | Equine influenza, canine parvovirus | Prohibited for use in poultry in the US Not approved for use in food animals |
CRI = constant-rate infusion; EHM = equine herpesvirus myeloencephalopathy; FeLV = feline leukemia virus; FHV-1= feline herpesvirus 1; FIP = feline infectious peritonitis; FIV = feline immunodeficiency virus aMaxwell LK. Antiherpetic drugs in equine medicine. Vet Clin North Am: Equine practice. 2017;33(1):99–125. doi:10.1016/j.cveq.2016.12.002 bCarmichael RJ, Whitfield C, Maxwell LK. Pharmacokinetics of ganciclovir and valganciclovir in the adult horse. J Vet Pharm Ther 36: 441–9. cSebbag L, Thomasy SM, Woodward AP, Knych HK, Maggs DJ. Pharmacokinetic modeling of penciclovir and brl42359 in the plasma and tears of healthy cats to optimize dosage recommendations for oral administration of famciclovir. Am J Vet Res. 2016 Aug 1;77(8):833–45. https://doi.org/10.2460/ajvr.77.8.833 | ||||