Development of sustained-release pellets to modulate the in vivo processes of the main active components of Danshen: A pharmacokinetic and pharmacodynamic evaluation

Danshen is a first-line traditional Chinese medicine derived from Salvia miltiorrhiza Bunge consisting mainly of tanshinone IIA, tanshinol, protocatechuic aldehyde, and salvianolic acid B, it is widely used to treat cardiovascular diseases based on the synergistic effect of its multiple active components. Recent studies have indicated that the overall effect of traditional Chinese medicine is closely related to the in vivo coexistence of a variety of active components.The prolongation of the coexistence of the four active components in Danshen in vivo by regulating their pharmacokinetic processes may contribute to better efficiency.Individual sustained-release pellets of the four main active components in Danshen were respectively prepared according to the optimised formulations developed in our previous studies to modulate their in vivo processes, in which the desired release profiles of each kind of sustained-release pellets for formulation optimisation were calculated based on the point-area deconvolution and circadian rhythm of variant angina. The four kinds of sustained-release pellets were filled into capsules on the basis of the original weight ratio of the four active components in purified Salvia miltiorrhiza extract for further in vitro release and pharmacokinetic and pharmacodynamic investigations.The release behaviours of the combined Danshen capsules composed of the four kinds of sustained-release pellets were evaluated in three media with different pH levels (pH 1.2, 6.8, and pure water). The release profiles of each kind of sustained-release pellets in pH 6.8 PBS and pH 1.2 HCl were similar to the release profile of those in pure water (similarity factors f2 > 50). Pharmacokinetic studies revealed that the four kinds of sustained-release pellets in the combined Danshen capsules possessed the same Tmax and similar and extended MRT. Moreover, pharmacodynamic studies indicated that the combined Danshen capsules had much better anti-angina effects than commercial Danshen capsules according to comprehensive evaluations via electrocardiogram, serum index (CK-MB, cTn-I, ET, and NO), myocardial oxidative damage, and myocardial pathologic biopsy.Sustained-release preparations can markedly prolong the in vivo coexistence of multiple components in Danshen to enhance their overall effects, which provides a potent strategy for developing the combination therapy of traditional Chinese medicine.