USA: Schedule II (oral and parenteral); Schedule III (rectal), UK: Class B Controlled Substance

20-45%

Renal

15-48 hours

D (USA)

Oral, Intravenous, Intramuscular, Rectal; also Intraperitoneal & Intracardiac (for animal euthanasia)

70-90% oral; 90% rectal

Hepatic