Pharmacokinetics and bioavailability of nimesulide in goats

The pharmacokinetic properties and bioavailability of cyclooxygenase (COX)‐2 selective nonsteroidal anti‐inflammatory drug nimesulide were investigated in female goats following intravenous (i.v.) and intramuscular (i.m.) administration at a dose of 4 mg/kg BW. Blood samples were collected by jugular venipuncture at predetermined times after drug administration. Plasma concentrations of nimesulide were determined by a validated high‐performance liquid chromatography method. Plasma concentration–time data were subjected to compartmental analysis and pharmacokinetic parameters for nimesulide after i.v. and i.m. administration were calculated according to two‐ and one‐compartment open models respectively. Following i.v. administration, a rapid distribution phase was followed by the slower elimination phase. The half‐lives during the distribution phase ( t 1/2 α ) and terminal elimination phase ( t 1/2 β ) were 0.11 ± 0.10 and 7.99 ± 2.23 h respectively. The steady‐state volume of distribution (V d(ss) ), total body clearance ( Cl B ) and mean residence time ( MRT ) of nimesulide were 0.64 ± 0.13 L/kg, 0.06 ± 0.02 L/h/kg and 11.72 ± 3.42 h respectively. After i.m. administration, maximum plasma concentration ( C max ) of nimesulide was 2.83 ± 1.11  μ g/mL attained at 3.6 ± 0.89 h ( t max ). Plasma drug levels were detectable up to 72 h. Following i.m. injection, the t 1/2 β and MRT of nimesulide were 1.63 and 1.73 times longer, respectively, than the i.v. administration. The bioavailability of nimesulide was 68.25% after i.m. administration at 4 mg/kg BW. These pharmacokinetic data suggest that nimesulide given intramuscularly may be useful in the treatment of inflammatory disease conditions in goats.