目的 研究硝苯地平緩釋片在Beagle犬體內(nèi)的藥動學(xué)和生物利用度。方法 采用雙周期隨機(jī)交叉試驗(yàn)設(shè)計(jì)，分別給予8只Beagle犬受試制劑（硝苯地平緩釋片）或參比制劑（硝苯地平控釋片）30 mg，采用LC-MS/MS法測定給藥后不同時(shí)間的血藥濃度。選用DAS 2.0軟件計(jì)算藥動學(xué)參數(shù)，并對藥代參數(shù)進(jìn)行配對t檢驗(yàn)統(tǒng)計(jì)分析。結(jié)果 血漿中硝苯地平線性范圍為0.05～30 ng/mL，最低定量限為0.05 ng/mL，分析方法靈敏、準(zhǔn)確、特異性高。受試制劑和參比制劑的峰濃度、達(dá)峰時(shí)間和藥-時(shí)曲線下面積分別為（4.46±2.11）、（5.21±2.68）ng/mL，（11.0±3.85）、（7.38±2.97）h，（49.5±25.9）、（49.6±25.2）ng?h/mL。以藥–時(shí)曲線下面積計(jì)算受試制劑的相對生物利用度為（104±43.5）%。結(jié)論 建立的分析方法操作簡單、準(zhǔn)確、重復(fù)性好，可用于犬體內(nèi)硝苯地平藥動學(xué)和相對生物利用度的研究；受試制劑具有一定的延遲釋放特征。

Objective To study the pharmacokinetics (PK) and bioavailability of Nifedipine Sustained-release Tablets (NSRT) in Beagle’s dogs. Methods Using dicycle randomized crossover study, test tablets (NSRT) or reference tablets (Nifedipine Controlled-release Tablets, NCRT) with the dose of 30 mg were given to eight Beagle’s dogs. The plasma concentration of nifedipine collected at different time points was determined by LC-MS/MS method. The main PK parameters were obtained by DAS 2.0 program. Results With the linear range of 0.05—30 ng/mL and the lower limit quantification of 0.05 ng/mL, the LC-MS/MS method had high sensitivity, accuracy, and specificity. The main PK parameters of NSRT and NCRT were as follows: the C_max were (4.46 ± 2.11) and (5.21 ± 2.68) ng/mL, the t_max were (11.0 ± 3.85) and (7.38 ± 2.97) h, and the AUC_0-t were (49.5 ± 25.9) and (49.6 ± 25.2) ng?h/mL. Compared to NCRT, the bioavailability of NSRT was (104 ± 43.5)%. Conclusion The method is simple and accurate for the determination of the drug plasma concentration with good repeatability, and is successfully applied to the bioavailability evaluation of NSRT in Beagle’s dogs. The NSRT has the feature of sustained release.