The effects of breed and routes of administration on the plasma pharmacokinetics and faecal excretion of robenacoxib in goats

Robenacoxib (RX) is a non-steroidal anti-inflammatory drug (NSAID) of the coxib class. This study aimed to evaluate the plasma dispositions and faecal excretion profiles of RX in Alpine and Saanen goats following oral and subcutaneous routes. Two different goat breeds were allocated into two treatment groups concerning the breed. RX was administered subcutaneously to animals at a dose of 4 mg/kg b.w. Following a one-week washout period, RX was administered by oral route to the same animals at the same dose. Heparinized blood samples were collected from all animals before drug administration (0 h) and subsequently up to 24 h. Faecal samples were collected at various times between 8 h and 36 h. The concentrations of RX in plasma and faeces were determined by HPLC. The plasma half-life (T_1/2λz) of RX in Saanen goats (1.21 h) was significantly longer (P < 0.017) than in Alpine goats (0.90 h) after subcutaneous administration. In both goat breeds, statistical differences were observed between subcutaneous and oral administration of RX for T_1/2λz, T_last, C_max, AUC_0-∞, and MRT_0-∞. Faecal C_max and T_max parameters following oral administrations were 0.92 µg/g and 0.85 µg/g at 30 h and at 24 h in Alpine and Saanen goats, respectively. The difference in plasma protein ratio between Alpine and Saanen goats may have affected the T_1/2λz of the drug. NSAIDs are among the drug groups frequently detected in aquatic and terrestrial ecosystems around the world and there are data on the effects of NSAID residues on wildlife and aquatic species. Therefore, revealing the excretion of NSAIDs, which are frequently used in the veterinary field, in faeces and urine should be considered for ecological sustainability.