Sofosbuvir/velpatasvir

NS5B polymerase inhibitor antiviral; extralabel use in cats for FIP and hepatitis C-like viral infections. NS5B RNA-dependent RNA polymerase inhibitor (sofosbuvir). Mechanism: prodrug — intracellularly phosphorylated to active uridine triphosphate analogue → competes with natural UTP → incorporates into viral RNA → chain termination. Active against hepatitis C NS5B polymerase. Used extralabel in cats for FIP in combination with velpatasvir (NS5A inhibitor). Key information Antiviral (HCV drug) — used off-label for feline infectious peritonitis (FIP) adjunctive therapy. Store at room temperature. Compounded or imported — verify quality. Used in combination therapy for FIP.

Oral (sofosbuvir/velpatasvir combination): Administer orally. May be given with food to improve compliance and reduce GI upset. Administer with food to reduce GI adverse effects. Administer daily for full prescribed course. Wear gloves when handling tablets. Store at room temperature; protect from light. If a dose is missed Administer as soon as you remember. If it is almost time for the next scheduled dose, skip the missed dose and resume the normal schedule. Never double up doses to make up for a missed one. Complete the course — used for FIP treatment.

GI: vomiting, anorexia, diarrhea (cats). Renal: azotemia (monitor renal function). Hepatic effects (monitor liver enzymes). Generally well tolerated in FIP cats at therapeutic doses. Teratogenic (do not use in pregnant animals).

For animals FIP treatment — administer full treatment course (typically 12 weeks). Monitor for FIP marker improvement (A:G ratio, effusion). Monitor renal function, hydration status, and urine output. Monitor liver enzymes with prolonged use. Avoid in pregnant animals. For people handling this medication Wear gloves when handling. Wash hands thoroughly with soap and water after handling. Antiviral — Keep out of reach of children. Pregnant women and women of childbearing age should avoid contact. Wear gloves when handling. Teratogenic potential.

Contact your veterinarian. Limited overdose data — GI signs most likely. Contact vet for guidance.