Absorption of grapiprant in red-tailed hawks (Buteo jamaicensis) is decreased when administered with food

OBJECTIVE Describe the pharmacokinetics of grapiprant administered orally with food to red-tailed hawks (RTHAs; Buteo jamaicensis) and compare the results with previously described grapiprant pharmacokinetics administered without food in this species. ANIMALS 6 healthy adult RTHA (3 males, 3 females) under human care. PROCEDURES A single dose of grapiprant (30 mg/kg) was given orally to RTHAs, followed by force-feeding. Blood samples were obtained at 14 time points for 120 hours postgrapiprant administration. Plasma concentrations of grapiprant were measured via tandem liquid chromatography-mass spectrometry. Nonparametric superimposition using pharmacokinetic modeling software used plasma concentrations to calculate simulations of grapiprant plasma concentrations for 30 mg/kg administered orally with food every 12 hours. RESULTS The arithmetic mean maximum plasma concentration was 405.8 ng/mL, time to maximum plasma concentration was 16 hours, and harmonic mean terminal half-life was 15.6 hours. Simulations determined 30 mg/kg every 12 hours could attain minimum effective concentrations (> 164 ng/mL) reported in dogs for a sustained period of approximately 20 hours.