Theophylline is a commonly used bronchodilator drug for treatment of chronic canine bronchitis, but no formulations validated in dogs are currently available. An oral, modified and compounded theophylline product (MCT), which could fulfil this need, is available through a USP-compliant, veterinary compounding pharmacy; however, its pharmacokinetic properties are unknown. The aim of this study was to determine the pharmacokinetics of MCT. Plasma drug concentrations were measured in seven healthy, fed dogs after single doses of intravenous aminophylline (8.6 mg/kg theophylline equivalent) and oral MCT (10 mg/kg). Systemic bioavailability of the MCT was 96.2 ± 32.9%. MCT times to maximum concentration, mean absorption time and terminal half-life were 8.85 ± 3.63, 6.95 ± 3.42, and 8.67 ± 1.62 hr, respectively. Based on simulations of 10 mg/kg and 12-hr dosing, steady-state plasma theophylline concentrations are expected to exceed the minimum therapeutic concentration for 71.7 ± 35.6% of the dosing interval. Overall, the MCT product investigated showed similar pharmacokinetic characteristics compared to previously validated extended-release theophylline products. An oral dose of 10 mg/kg q 12 hr is likely an appropriate dosage to begin therapy; however, therapeutic drug monitoring may be warranted because of inter-individual variation.

中文翻译：

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改良的复合茶碱产品在犬中的药代动力学。

茶碱是用于治疗慢性犬支气管炎的常用支气管扩张药，但目前尚无在犬中验证过的制剂。可以满足这种需求的口服，修饰和复方茶碱产品（MCT）可通过符合USP的兽医复方药店获得；但是，它的药代动力学特性是未知的。这项研究的目的是确定MCT的药代动力学。在单剂量静脉内给予氨茶碱（8.6 mg / kg茶碱当量）和口服MCT（10 mg / kg）后，对七只健康的喂食犬的血浆药物浓度进行了测量。MCT的全身生物利用度为96.2±32.9％。达到最大浓度的MCT时间，平均吸收时间和终末半衰期分别为8.85±3.63、6.95±3.42和8.67±1.62 hr。基于10 mg / kg和12小时给药的模拟，稳态血浆茶碱浓度在给药间隔的71.7±35.6％时有望超过最小治疗浓度。总体而言，与先前验证的缓释茶碱产品相比，所研究的MCT产品显示出相似的药代动力学特征。口服剂量为10 mg / kg q 12 hr可能是开始治疗的适当剂量；但是，由于个人之间的差异，可能需要对治疗药物进行监控。口服剂量为10 mg / kg q 12 hr可能是开始治疗的合适剂量；但是，由于个体差异，可能需要对治疗药物进行监测。口服剂量为10 mg / kg q 12 hr可能是开始治疗的合适剂量；但是，由于个体差异，可能需要对治疗药物进行监测。