Studies On Pharmacokinetics Of Carvedilol In Human Subjects And The Construction Of PK-PD Model

Objective: 1. To establish a HPLC-FL method for the determination of carvedilol in human plasma. 2. To study the pharmacokinetics and bioavailability of carvedilol tablets in healthy volunteers, and to evaluate its characteristics of absorption, distribution, elimination and excretion kinetics. 3. To construct the PK-PD model of carvedilol in healthy subjects.Methods: 1. Plasma samples were detected by HPLC-FL method. The separation was performed on XBP-C₁₈(250mm×4.6 mm, 5μm) column. The excitation and emission wavelengths were set at 285 and 340 nm, respectively. The mobile phase was composed of 0.05M ammonium formate (with 0.1% formic acid) and methanol (45:55, v/v) at a flow rate of 1ml·min^-1. 2. Twenty male healthy Chinese volunteers were divided into two groups randomly according to two period cross-over test design. Volunteers were orally given the test or reference preparation of 20mg carvedilol tablets during the two periods. Plasma samples were collected before and 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0, 8.0, 10.0, 12.0, 24.0h after administration, and was separated, then frozen immediately at -20℃until analysis. The second period experiment was carried out same as above method 1 week's later. The pharmacokinetic parameters of carvedilol were calculated and evaluated by software of DAS 2.0. Relative bioavailability was calculated according to the AUC. Analysis of variance, t-test and (1-2α) confidence interval were used to evaluate the bioequivalence of test and reference preparation. 3. The mean arterial blood pressure was recorded and the pharmacodynamics of carvedilol were characterized by tail-cuff manometry.Results: 1.The linear range of the calibration curve for determination of carvedilol by HPLC-FL was l-160ng·mL^-1 with a correlation coefficient was 0.9981. The Absolute recovery was 59.59%-65.30%. The intra- and inter-day RSD were less than 6.86% and 6.23%. Carvedilol was stable when storage at -20℃for seven days and after two freeze-thawing cycles. 2. The main pharmacokinetic parameters of test and reference preparation of carvedilol tablets were respectively as follows: t_1/2 (4.557±2.557) h and (3.417±1.739) h, Tmax (1.125±0.497)h and (1.188±0.343)h, Cmax (46.294±21.069) ng·mL^-1 and (44.645±17.446) ng·mL^-1 , AUC_0-24 (164.413±83.290)ng·mL^-1·h and (156.113±69.710) ng·mL^-1·h, AUC_0-∞ (173.759±87.361) ng·mL^-1·h and (160.980±69.730) ng·mL^-1·h. The relative bioavailability of carvedilol test preparation was 104.1%±18.5%. 3. The K_e0 was 0.35±0.27h^-1, the EC₅₀ was 24.3±24.3ng·ml^-1, and the AUE was 5.65±2.54%·h for the effect-compartment model.Conclusions: 1. The developed method was sensitive and accurate. It can be used to determine the concentration of carvedilol in human plasma. 2. The relative bioavailability of carvedilol test preparation was 104.1%±18.5%. 3. Analysis of multiple factor variance indicated that there was no significant difference between preparations and periods, but statistical difference was observed between individuals. Bioequivalence hypothesis between individuals, periods and preparations validated by further t-test and (1-2α) confidence interval analysis indicated that the test preparation was bioequivalence to the reference preparation.