Capsaicinoids deter horses from chewing on bandages and are applied topically to provide analgesia to musculoskeletal injuries. They are banned during competition due to their nerve blocking properties. The pharmacokinetics of oral (PO) and direct gastric administration via nasogastric tube (NG), or topical (TOP) administration of two capsaicinoid-containing products were investigated, and the withdrawal times required prior to competition were estimated. Capsaicin (CAP) and dihydrocapsaicin (DCAP) were quantified in plasma, and both compounds were best described by a delayed absorption two compartment elimination model following PO administration and by a first order absorption one compartment elimination model following TOP administration. Capsaicin and DCAP could not be quantified in most samples following NG administration. Following PO administration, the time to maximum plasma concentration (T_max) for CAP and DCAP was 0.25 (0.08–0.50) hr. Following TOP application, the Tmax for CAP and DCAP was 4 (2–6) and 5 (3–12) hr, respectively. By 8 hr post-PO administration and 36 hr post-TOP application, CAP and DCAP were below the lower limit of quantification. Capsaicin and DCAP were not detected in urine samples. Withdrawal times were predicted using the 99.99% credibility interval limits of the pharmacokinetic parameters calculated with Bayesian estimation.

中文翻译：

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使用药代动力学参数对马施用的两种含有辣椒素的产品进行基于贝叶斯的戒断估计

辣椒素类物质可阻止马咀嚼绷带，并局部应用以镇痛肌肉骨骼损伤。由于它们的神经阻滞特性，它们在比赛期间被禁止。研究了口服 (PO) 和经鼻胃管 (NG) 直接胃给药或两种含辣椒素产品的局部 (TOP) 给药的药代动力学，并估计了比赛前所需的停药时间。对血浆中的辣椒素 (CAP) 和二氢辣椒素 (DCAP) 进行定量，这两种化合物通过 PO 给药后的延迟吸收双室消除模型和 TOP 给药后的一级吸收单室消除模型进行了最好的描述。NG 给药后，大多数样品中的辣椒素和 DCAP 无法定量。CAP 和 DCAP 的T _max ) 为 0.25 (0.08–0.50) 小时。TOP 应用后，CAP 和 DCAP 的 Tmax 分别为 4 (2-6) 和 5 (3-12) 小时。通过 PO 给药后 8 小时和 TOP 应用后 36 小时，CAP 和 DCAP 低于量化下限。尿样中未检测到辣椒素和 DCAP。使用贝叶斯估计计算的药代动力学参数的 99.99% 可信区间限制预测停药时间。