Meloxicam is routinely used for pain alleviation in pre-ruminant calves during husbandry procedures. The pharmacokinetics of a single dose (0.5 mg/kg) of meloxicam was investigated after intravenous (IV), subcutaneous (SC), and oral (PO) administration in 30 pre-ruminant calves. Each group included 10 calves. Oral meloxicam was administered at least 1 h after feeding. Plasma samples were collected for up to 168 h, and the meloxicam concentration was analysed with liquid chromatography and mass spectrometry, followed by a noncompartmental pharmacokinetic analysis. The maximum meloxicam concentrations in plasma were 1.91 ± 0.27 μg/mL and 1.77 ± 0.16 μg/mL after SC and PO routes, respectively. The time of maximum concentration was 7.6 ± 2.8 h after SC and 10.0 ± 5.7 h after PO administration. The approximate bioavailability of meloxicam was 97% for SC and PO routes. The elimination half-lives were 79.2 ± 12.4, 84.6 ± 24.8, and 84.8 ± 22.3 h after IV, SC, and PO routes, respectively. The results suggest that the therapeutic meloxicam concentrations in plasma that are required for pain relief in other species, such as horses, may be maintained for several days following a single dose (0.5 mg/kg) administered IV, SC, or PO in calves.

中文翻译：

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美洛昔康在反刍前犊牛静脉、口服和皮下给药后的药代动力学

美洛昔康通常用于在饲养过程中缓解反刍前犊牛的疼痛。在 30 只反刍前小牛静脉内 (IV)、皮下 (SC) 和口服 (PO) 给药后，研究了单剂量 (0.5 mg/kg) 美洛昔康的药代动力学。每组包括 10 头小牛。喂食后至少1小时口服美洛昔康。收集血浆样本长达 168 小时，并使用液相色谱和质谱分析美洛昔康浓度，然后进行非房室药代动力学分析。SC和PO途径后血浆中美洛昔康的最大浓度分别为1.91±0.27μg/mL和1.77±0.16μg/mL。最大浓度时间为SC后7.6±2.8小时和PO给药后10.0±5.7小时。对于 SC 和 PO 途径，美洛昔康的生物利用度约为 97%。IV、SC和PO途径后的消除半衰期分别为79.2±12.4、84.6±24.8和84.8±22.3小时。结果表明，在其他物种（例如马）中，在静脉注射、皮下注射或口服单剂量（0.5 mg/kg）后，血浆中美洛昔康的治疗浓度可以维持数天，而该浓度是缓解其他物种（例如马）疼痛所需的。