Department of Veterinary Diagnostic and Production Animal Medicine (VDPAM), College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
BMC Vet Res. 2012 Jun 21;8:85. doi: 10.1186/1746-6148-8-85.
South American camelids in the United States have rapidly developed into an important agricultural industry in need of veterinary services. Pain management is challenging in camelids because there are no drugs currently approved by the U.S. Food and Drug Administration for use in these species. Dosage regimens used for many therapeutic drugs have been extrapolated from other ruminants; however, the pharmacokinetics, in camelids, may differ from those of other species. Studies investigating the pharmacokinetics of cyclooxygenase-2 (COX-2) selective non-steroidal anti-inflammatory drugs in camelids are deficient in the published literature. Six adult llamas (121- 168 kg) were administered either a 1 mg/kg dose of oral or a 0.5 mg/kg dose of IV meloxicam in a randomized cross-over design with an 11 day washout period between treatments. Plasma samples collected up to 96 hours post-administration were analyzed by high pressure liquid chromatography and mass spectrometry detection (HPLC-MS) followed by non-compartmental pharmacokinetic analysis.
A mean peak plasma concentration (CMAX) of 1.314 μg/mL (Range: 0.826 - 1.776 μg/mL) was recorded at 21.4 hours (Range: 12.0 - 24.0 hours) with a half-life (T ½ λz) of 22.7 hours (Range: 18.0 - 30.8 hours) after oral meloxicam administration. In comparison, a half-life (T ½ λz) of 17.4 hours (Range: 16.2 - 20.7 hours) was demonstrated with IV meloxicam administration. The oral bioavailability (F) of meloxicam (dose normalized) was 76% (Range: 48 - 92%). No adverse effects associated with either treatment modality were observed in the llamas.
The mean bioavailability (F) of oral meloxicam was 76% indicating a high degree of gastrointestinal absorption. Plasma meloxicam concentrations >0.2 μg/mL were maintained for up to 72 h after oral administration; >0.2 μg/mL is considered to be the concentration of meloxicam required for analgesic effects in other species such as the horse. These data suggest that a single dosage of oral meloxicam at 1 mg/kg could potentially maintain therapeutic concentrations in plasma for up to 3 days in adult llamas.
美国的南美骆驼已迅速发展成为一个需要兽医服务的重要农业产业。在骆驼中进行疼痛管理具有挑战性，因为目前没有美国食品和药物管理局批准用于这些物种的药物。许多治疗药物的剂量方案是从其他反刍动物推断出来的；然而，骆驼的药代动力学可能与其他物种不同。在已发表的文献中，关于环氧化酶-2（COX-2）选择性非甾体抗炎药在骆驼中的药代动力学研究还很缺乏。在一项随机交叉设计中，六只成年美洲驼（121-168 公斤）分别给予口服 1 毫克/公斤剂量或静脉内 0.5 毫克/公斤剂量的美洛昔康，两种治疗之间有 11 天的洗脱期。给药后长达 96 小时采集的血浆样本通过高效液相色谱和质谱检测（HPLC-MS）进行分析，然后进行非房室药代动力学分析。
口服美洛昔康后 21.4 小时（范围：12.0-24.0 小时）记录到平均峰值血浆浓度（CMAX）为 1.314μg/mL（范围：0.826-1.776μg/mL），半衰期（T½λz）为 22.7 小时（范围：18.0-30.8 小时）。相比之下，静脉内美洛昔康给药的半衰期（T½λz）为 17.4 小时（范围：16.2-20.7 小时）。口服美洛昔康（剂量归一化）的生物利用度（F）为 76%（范围：48%-92%）。在美洲驼中，未观察到与两种治疗方式相关的不良反应。
口服美洛昔康的平均生物利用度（F）为 76%，表明胃肠道吸收程度很高。口服给药后，血浆中美洛昔康浓度>0.2μg/mL 可维持长达 72 小时；>0.2μg/mL 被认为是其他物种（如马）镇痛作用所需的美洛昔康浓度。这些数据表明，成年美洲驼口服 1 毫克/公斤美洛昔康单次剂量可能在长达 3 天的时间内维持血浆中的治疗浓度。
