Pharmacokinetics of three formulations of vitacoxib in horses

Abstract

The pharmacokinetic properties of three formulations of vitacoxib were investigated in horses. To describe plasma concentrations and characterize the pharmacokinetics, 6 healthy adult Chinese Mongolian horses were administered a single dose of 0.1 mg/kg bodyweight intravenous (i.v.), oral paste, or oral tablet vitacoxib in a 3‐way, randomized, parallel design. Blood samples were collected prior to and at various times up to 72 hr postadministration. Plasma vitacoxib concentrations were quantified using UPLC‐MS/MS, and pharmacokinetic parameters were calculated using noncompartmental analysis. No complications resulting from the vitacoxib administration were noted on subsequent administrations, and all procedures were tolerated well by the horses throughout the study. The elimination half‐life (T1/2λz) was 4.24 ± 1.98 hr (i.v.), 8.77 ± 0.91 hr (oral paste), and 8.12 ± 4.24 hr (oral tablet), respectively. Maximum plasma concentration (Cmax) was 28.61 ± 9.29 ng/ml (oral paste) and 19.64 ± 9.26 ng/ml (oral tablet), respectively. Area under the concentration‐versus‐time curve (AUClast) was 336 ± 229 ng hr/ml (i.v.), 221 ± 94 ng hr/ml (oral paste), and 203 ± 139 ng hr/ml, respectively. The results showed statistically significant differences between the 2 oral vitacoxib groups in Tmax value. T1/2λz (hr), AUClast (ng hr/ml), and MRT (hr) were significantly different between i.v. and oral groups. The longer half‐life observed following oral administration was consistent with the flip‐flop phenomenon.

Non-Steroidal Anti-Inflammatory Drugs and Associated Toxicities in Horses

“…Further research, ideally randomised studies with larger sample sizes, is required to determine the analgesic effect of COX-2 selective NSAIDs for conditions in equine veterinary medicine and their pharmacokinetics in the critically ill horses [ 50 ]. Other newer COX-2 selective drugs, such as vitacoxib and celecoxib, have recently had pharmacokinetic studies performed in horses [ 23 , 52 ]. While no analgesic studies have yet been published, these drugs may provide future avenues for analgesia in equine veterinary medicine.…”

Non-Linear Mixed-Effects Pharmacokinetic Modeling of the Novel COX-2 Selective Inhibitor Vitacoxib in Cats

“…Vitacoxib is a highly selective cyclooxygenase-2 (COX-2) inhibitor ( 6 ) registered for use in dogs in China for the treatment of pain resulting from orthopedic and soft tissue surgery, osteoarthrosis, and rheumatoid arthritis ( 7 ). The safety profile of vitacoxib was initially established in rats ( 8 – 11 ) and more recently reported in young adult horses ( 12 , 13 ), rabbits ( 14 ), beagle dogs ( 15 ) and cats ( 16 ).…”