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Pharmacokinetics of meloxicam in plasma and urine of horses

Pierre-Louis ToutainUMR 181 Physiopathologie et Toxicologie Expérimentales, INRA/ENVT, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, 31076 Toulouse, France.

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Nadège ReymondUMR 181 Physiopathologie et Toxicologie Expérimentales, INRA/ENVT, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, 31076 Toulouse, France.

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Valérie LarouteUMR 181 Physiopathologie et Toxicologie Expérimentales, INRA/ENVT, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, 31076 Toulouse, France.

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Patrice GarciaLaboratoire des Courses Hippiques, 15 rue de Paradis, 91270 Verrières le Buisson, France.

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Marie-Agnès PopotLaboratoire des Courses Hippiques, 15 rue de Paradis, 91270 Verrières le Buisson, France.

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Yves BonnaireLaboratoire des Courses Hippiques, 15 rue de Paradis, 91270 Verrières le Buisson, France.

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Alexandra HirschBoehringer Ingelheim Vetmedica GmbH, 55216 Ingelheim, Germany.

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Rüdiger NarbeBoehringer Ingelheim Vetmedica GmbH, 55216 Ingelheim, Germany.

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Abstract

Objective—To determine pharmacokinetic parameters for meloxicam, a nonsteroidal anti-inflammatory drug, in horses.

Animals—8 healthy horses.

Procedure—In the first phase of the study, horses were administered meloxicam once in accordance with a 2 × 2 crossover design (IV or PO drug administration; horses fed or not fed). The second phase used a multiple-dose regimen (daily oral administration of meloxicam for 14 days), with meloxicam administered at the recommended dosage (0.6 mg/kg). Plasma and urine concentrations of meloxicam were measured by use of validated methods with a limit of quantification of 10 ng/mL for plasma and 20 ng/mL for urine.

Results—Plasma clearance was low (mean ± SD; 34 ± 0.5 mL/kg/h), steady-state volume of distribution was limited (0.12 ± 0.018 L/kg), and terminal half-life was 8.54 ± 3.02 hours. After oral administration, bioavailability was nearly total regardless of feeding status (98 ± 12% in fed horses and 85 ± 19% in nonfed horses). During once-daily administration for 14 days, we did not detect drug accumulation in the plasma. Meloxicam was eliminated via the urine with a urine-to-plasma concentration that ranged from 13 to 18. Concentrations were detected for a relatively short period (3 days) after administration of the final daily dose.

Conclusions and Clinical Relevance—Results of this study support once-daily administration of meloxicam regardless of the feeding status of a horse and suggest a period of at least 3 days before urine concentrations of meloxicam reach concentrations that could be used in drug control programs. (Am J Vet Res 2004;65:1542–1547)

Abstract

Objective—To determine pharmacokinetic parameters for meloxicam, a nonsteroidal anti-inflammatory drug, in horses.

Animals—8 healthy horses.

Procedure—In the first phase of the study, horses were administered meloxicam once in accordance with a 2 × 2 crossover design (IV or PO drug administration; horses fed or not fed). The second phase used a multiple-dose regimen (daily oral administration of meloxicam for 14 days), with meloxicam administered at the recommended dosage (0.6 mg/kg). Plasma and urine concentrations of meloxicam were measured by use of validated methods with a limit of quantification of 10 ng/mL for plasma and 20 ng/mL for urine.

Results—Plasma clearance was low (mean ± SD; 34 ± 0.5 mL/kg/h), steady-state volume of distribution was limited (0.12 ± 0.018 L/kg), and terminal half-life was 8.54 ± 3.02 hours. After oral administration, bioavailability was nearly total regardless of feeding status (98 ± 12% in fed horses and 85 ± 19% in nonfed horses). During once-daily administration for 14 days, we did not detect drug accumulation in the plasma. Meloxicam was eliminated via the urine with a urine-to-plasma concentration that ranged from 13 to 18. Concentrations were detected for a relatively short period (3 days) after administration of the final daily dose.

Conclusions and Clinical Relevance—Results of this study support once-daily administration of meloxicam regardless of the feeding status of a horse and suggest a period of at least 3 days before urine concentrations of meloxicam reach concentrations that could be used in drug control programs. (Am J Vet Res 2004;65:1542–1547)