Pharmacokinetics of maropitant citrate in Rhode Island Red chickens (Gallus gallus domesticus) following subcutaneous administration

Maropitant citrate is a synthetic neurokinin‐1 receptor antagonist and substance P inhibitor used for control of emesis in dogs in cats. Maropitant citrate is used empirically in birds, despite a lack of pharmacokinetic data in avian species. The objective of this study was to determine the pharmacokinetic profile of a single dose of maropitant citrate 1 and 2 mg/kg subcutaneously (SC) in eight Rhode Island Red hens (Gallus gallus domesticus). A crossover study design was used with 1‐week washout between trials. Blood samples were collected over 36 h after drug administration. Plasma concentrations were measured using liquid chromatography–tandem mass spectrometry and pharmacokinetic parameters were determined via non‐compartmental analysis. The mean maximum plasma concentration, time to maximum concentration, and elimination half‐life following 1 and 2 mg/kg SC were 915.6 ± 312.8 ng/ml and 1195.2 ± 320.2 ng/ml, 0.49 ± 0.21 h and 1.6 ± 2.6 h, and 8.47 ± 2.24 h and 8.58 ± 2.6 h, respectively. Pharmacokinetic data suggests doses of 1 or 2 mg/kg SC may be administered every 12–24 h to maintain above target plasma concentration similar to dogs (90 ng/ml). These data provide a basis for further investigation of maropitant citrate pharmacokinetics and pharmacodynamics in birds.