GS-441524 (GS) dosing for feline infectious peritonitis (FIP) is form-dependent, with higher doses required for neurological and ocular disease due to limited blood-brain and blood-ocular barrier penetration. The standard oral treatment duration is 84 days (12 weeks), followed by an 84-day observation period.Frontiers in Ve…

For effusive FIP, oral GS-441524 is dosed at 12.5–25 mg/kg/day, with the lower end of this range used for uncomplicated effusive disease.Frontiers in Ve… Subcutaneous GS-441524 at 4.0 mg/kg SC q24h for at least 12 weeks was established as the effective dose in the foundational field trial, where 2.0 mg/kg SC q24h produced an unacceptable relapse rate.Journal of Feli… Oral dosing of 10–15 mg/kg q24h has been used successfully in effusive and non-effusive disease, with remission achieved by day 84 in 56% of cats on this regimen; cats requiring retreatment responded to escalation to 15–20 mg/kg.Journal of Vete… Across 84-day oral treatment protocols, success rates are 82.2% for effusive FIP, 85.1% for mixed effusive/non-effusive FIP, and 93.9% for non-effusive FIP.Journal of Feli…

Neurological FIP requires dose escalation to 5–10 mg/kg SC q24h for at least 84 days. At 5 mg/kg SC q24h, two less severely affected neurological cases resolved, but the most severely affected cat failed to respond until stepwise escalation to 10 mg/kg.Journal of Vete… This pharmacokinetic rationale is supported by cerebrospinal fluid concentrations of GS-441524 measuring approximately 20% of plasma concentration, with a 10 mg/kg dose achieving CSF concentrations of 0.8–2.7 μM.Journal of Vete… Oral dosing of 10–20 mg/kg/day has been used with successful results in neurological cases.Journal of Vete… Overall survival for neurological FIP is 60%.Journal of Feli…

Ocular FIP is treated at the same higher dose range of up to 20 mg/kg/day, reflecting similarly limited drug penetration through the blood-ocular barrier, with 22–33% of plasma concentration detected in the aqueous humor.Journal of Vete… Ocular FIP carries the highest survival rate at 100% in one cohort.Journal of Feli… Of cats presenting with both ocular and neurological disease treated with higher doses, 80% recovered fully.Journal of Vete…

Splitting the daily oral GS-441524 dose into twice-daily administration may optimize serum concentrations, though the standard published protocols use once-daily dosing.Journal of Vete… A 42-day treatment duration has shown promising results for effusive FIP, though 84 days remains the established standard.Journal of Vete…

Remdesivir (GS-5734), the prodrug of GS-441524, is used as an induction agent at 10–15 mg/kg IV or SC q24h for 4 doses, followed by transition to oral GS-441524 at 10–15 mg/kg q24h for at least 84 days total.Journal of Vete… Clinical response to treatment is typically observed within 1–5 days of initiation; cats surviving the first 3 days have an excellent prognosis, with 92.8% alive and in clinical remission at 12 weeks.Journal of Vete…

Adverse effects are generally mild and transient. Vomiting occurs in 33% and diarrhea in 29% of cats on oral GS-441524.Journal of Feli… Subcutaneous injection site reactions and discomfort are the primary adverse effects with parenteral administration.Journal of Vete… GS-441524 is contraindicated in cats not confirmed to have FIP, as feline coronavirus can develop antiviral resistance, and the consequences of under- or overdosing with unlicensed preparations are not fully characterized.Journal of Feli…

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