Effects of Danshen tablets on pharmacokinetics of amlodipine in rats.

CONTEXT

Danshen tablets (DST), an effective traditional Chinese multi-herbal formula, are often combined with amlodipine (ALDP) for treating coronary heart disease.

OBJECTIVE

This study investigated the effects of DST on the pharmacokinetics of ALDP and the potential mechanism.

MATERIALS AND METHODS

The pharmacokinetics of ALDP (1 mg/kg) in male Sprague-Dawley rats (n = 6), with or without pretreatment of DST (100 mg/kg for 7 d), were investigated using LC-MS/MS. The effects of DST on the metabolic stability of ALDP were also investigated using rat liver microsomes (RLM).

RESULTS

The results indicated that C (16.25 ± 2.65 vs. 22.79 ± 2.35 ng/ml), AUC (222.87 ± 59.95 vs. 468.32 ± 69.87 n gh/ml), and t (10.60 ± 1.05 vs. 14.15 ± 1.59 h) decreased significantly when DST and ALDP were co-administered, which suggested that DST might influence the pharmacokinetic behaviour of ALDP when they are co-administered. The metabolic stability of ALDP was also decreased (23.6 ± 4.7 vs. 38.9 ± 5.2) with the pretreatment of DST.

DISCUSSION AND CONCLUSIONS

This study indicated that DST could accelerate the metabolism of ALDP in RLM and change the pharmacokinetic behaviours of ALDP. Accordingly, these results showed that the herb-drug interaction between DST and ALDP might occur when they were co-administered. Therefore, the clinical dose of ALDP should be increased when DST and ALDP are co-administered.