Effects of four traditional Chinese medicines on the pharmacokinetics of simvastatin.

1. Concomitant traditional Chinese medicines (TCMs) could be the reason for relative poor efficacy of statins in dyslipidemia patients in China. 2. An open-label, randomized, 5-period crossover study in healthy Chinese was designed to evaluate the pharmacokinetic interaction and tolerability of multiple doses of certain TCMs on a single dose of simvastatin. In each period, subjects received one of five treatments. In Treatment A, subjects received a single dose of 20 mg simvastatin. In Treatment B, C, D or E, subjects received Tong Xin Luo, Nao Xin Tong, Guan Mai Ning or Yin Xing Ye for 7 days and a single dose of 20 mg simvastatin on Day 7. The washout period was 7 days. 3. The 97.5% confidence interval of the AUC0-48 h geometric mean ratio of simvastatin acid and simvastatin for simvastatin given after multiple oral doses of one of the TCMs versus simvastatin given alone were fully contained within the prespecified bounds of (0.50, 2.00). 4. Exposures to simvastatin acid and simvastatin following a single dose of simvastatin alone were similar to those following coadministration of a single dose of simvastatin with multiple doses of each of the TCM preparations tested. Simvastatin and these TCMs were well tolerated.