PHARMACOKINETICS OF MELOXICAM AFTER INTRAVENOUS ADMINISTRATION IN HORSES AFFECTED BY COLIC SYNDROME

Objectives: In horses undergoing laparotomy for colic syndrome, NSAIDs are the first choice treatment in the postoperative period because of their ability to contrast endotoxemia and to promote analgesic and anti-inflammatory effect. Since the pharmacokinetics of drugs in clinical patients may be different (presence of pathologies and other therapeutic agents) from that reported in healthy subjects, this study was aimed to evaluate the pharmacokinetic profile of meloxicam after IV administration in horses undergoing anesthesia surgery for colic syndrome. Materials & methods: Eight horses presenting colic syndrome and scheduled for laparotomy were enrolled in the study. All subjects received the same premedication and anesthetic protocol, as well as antibiotics before and after surgery. During all the surgery period and for at least 12 hours of the postoperative period a ringer lactate solution was infused at different rates depending on the dehydration state of the patient. Next the end of surgery (at least 30 min before) 0.6 mg/kg of meloxicam were administered intravenously. Blood samples were withdrawn at prefixed time-points within the 24 hours post-administration in order to determine the concentration vs time profile curves of meloxicam. The analytical quantification of the drug was performed by HPLC with an UV detector. A bi-compartmental model best fitted the obtained data. Results & Conclusion: The half-life of elimination resulted equal to 5.03 ± 2.49 hours, the clearance was 71.34 ± 75.47 mL/kg/h and the distribution volume at steady state 0.38 ± 0.41 L/kg. Comparing these data with data reported in healthy horses, the clearance is greater and as consequence the half-life smaller. This difference is probably due to the continuous infusion of ringer lactate that promotes the elimination of drug. In this clinical condition, the recommended dose of 0.6 mg/kg/die might not be sufficient to guarantee the analgesic efficacy