Evaluation of Warfarin Clinical Pharmacokinetics in a Medical Center

• Main Authors: Pi-Lai Tseng, 曾碧萊
• Other Authors: Yung-Jin Lee
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/14123476232308153317

碩士 === 高雄醫學大學 === 藥學研究所碩士在職專班 === 95 === Objects：This study was to compare the predictive ability using warfarin dosage to estimate the INR with two clinical pharmacokinetic tools, the JPKD and tdm for R. And also to evaluate the warfarin dosage and INR data in Chinese patients. Methods：The NHI reimbursement claimed data of 2005 was retrieved from a medical center, in which all the prescribing information of warfarin in the ambulatory settings was included. However, cases such as unmatched frequency, unchanged dosage, interactions with first and second degree, abNormalized INR and/or without INR were excluded. Based on this information, cases having both of the dosage change and the INR at steady state were consequently collected for further evaluation. A set of pharmacokinetic (PK) parameters observed from the first warfarin dosage and the subsequent INR of each case was estimated by both JPKD and tdm for R. Then a new INR was estimated by using the second dosage with the previously calculated PK parameters. Thus, the precisions expressed as absolute prediction error (APE %) and Similarity could be calculated from the observed and the predicted INRs. Also, drug interaction with lessen degree was taken into account to compare the differences between the two PK models. Results：Seventy cases without any drug interactions were studied. The APE ( %) and Similarity estimated by the JPKD and tdm for R were 15.0 ± 12.8, 14.0 ± 10.7 and 0.976 ± 0.196, 0.975 ± 0.175 respectively. There was no significance differences between these two groups using paired sample t-test (p = 0.46 and 0.94). For another 62 cases with 4 to 5 degreed drug interactions, APE ( %) and Similarity estimated by JPKD and tdm for R were 15.1 ± 10.7, 12.9 ± 10.2 and 0.940 ± 0.176, 0.942 ± 0.154 respectively. There was significance differences of APE between groups (p = 0.02), but no differences of Similarity between groups (p = 0.90). In comparison with JPKD and tdm for R model, the results were shown not significant (p=0.96 vs 0.28 and p=0.53 vs 0.26) respectively while using independent t-test to test the significant difference of the APE % and Similarity between without and with drug interaction group. At last, all the cases being with and without drug interactions were pooled together and APE % and Similarity were estimated by JPKD and tdm for R as 15.1 ± 11.8, 13.5 ± 10.5 and 0.959 ± 0.187, 0.959 ± 0.166 respectively. There was no significant differences between these two groups with the paired sample t-test (p=0.06 and 0.98). The average observed INR of all the cases was 1.57 ± 0.45, and the predicted value estimated by JPKD and tdm forR were 1.47 ± 0.37 and 1.47 ± 0.36 respectively. The average warfarin daily dose was 2.62 ± 1.18 mg. Conculsions：Firstly, The result indicated that the predictive ability using both pharmacokinetic tools were no significant differences between the groups with and without any drug interactions. No matter what there were drug-drug interactions existed or not, no influences for both tools to predict the INR were observed. Secondly, there was no clinically differences between the observed and predicted INR values estimated by both tools. The average daily dose was similar to that recommended by the literature for Chinese people.