Abstract
Sodium tanshinone IIA sulfonate (STS) is a water-soluble derivative of tanshinone IIA, a famous Chinese medicine which has been used in the treatment of cardiovascular disorders for many years. Using caffeine as a probe drug, this project was designed to investigate the effect of STS on the activity of CYP1A2 in humans.
Sixteen unrelated healthy volunteers were recruited for this two-phase, randomized and crossover study. The volunteers received either placebo or 60 mg day−1 of STS injections through vein for 13 days. Pharmacokinetics of caffeine and the metabolite paraxanthine was determined by high-performance liquid chromatography. CYP1A2 activity was monitored by the ratio of paraxanthine to caffeine at 6 h in plasma.
Enzyme activity analysis showed that STS significantly increased the activity of CYP1A2 by 41.1% [90% confidence interval (CI), 17.4–64.8%] (p = 0.036). The area under the curve [AUC(0–24h)] of caffeine significantly decreased by 13.3% [90% CI = 7.0–19.6%] (p = 0.005) with 13 days of treatment of STS. AUC(0–24h) of paraxanthine significantly increased by 17.4% [90% CI = 4.3–30.5%] (p = 0.035). No significant difference was found for other parameters of caffeine and paraxanthine between two phases.
STS has significantly induced the activity of CYP1A2 in vivo. Simultaneously, AUC(0–24h) of caffeine and paraxanthine were significantly affected by STS. The findings have provided some useful information for safe and effective usage of STS in clinic.
Acknowledgements
The authors are grateful to Carefree Pharmaceutical Ltd, Jiangsu, P. R. China, for generously providing sodium tanshinone II A sulfonate injections. They thank Professor Ze-neng Cheng (Pharmacy Faculty of Central South University, P. R. China) for his assistance during the experiments. They also give their appreciation to the National Natural Science Foundation of China (Grant Numbers 30572226, 30472054, 30801421, 30528026, 30672497, and 30500623) and the Foundation for Young Teachers from the National Ministry of Education (Grant Number 20070533002).
Declaration of interest: The authors report no conflicts of interest.