Improvement of Bioavailability and Dissolution of Tanshinone IIA by Encapsulating it with Hydroxypropyl-β-Cyclodextrin

Background: Tanshinone IIA(TA) could be used for the treatment of some diseases. However, the clinical application of TA was hindered by its poor water - solubility and low oral bioavailability, etc. The aim of this study was to improve its oral bioavailability and dissolution by encapsulating TA with hydroxypropyl–beta–cyclodextrin (HP-β-CD).
Methods: The encapsulation composite of HP-β-CD/TA was prepared through solution method with optimization of response surface test design by taking encapsulation efficiency and drug loading as the goals; the in-vitro dissolution and in-vivo metabolism of the composite in rats were evaluated.
Results: The optimal concentration of HP-β-CD in water was 0.4 g/mL; the optimal ratio of TA to HP-β-CD was 1:7 in weight for the encapsulating process at 50°C with stirring for 2h; the encapsulation efficiency and drug loading were 84.06% and 7.38%, respectively; the cumulative release of TA from HP–β -CD TA composite in vitro dissolution reached to 72% within 90 min, which was 3.78 times of that of the original TA substance; the area under the curves of AUC(0-t) and AUC(0-∞) of the HP–β –CD -TA inclusion composite were 3.71 and 3.42 times of the original TA substance under p<0.01, respectively. The apparent distribution volume VZ/F and the clearance rate VLZ/F of HP–β –CD -TA inclusion composite decreased by 7.71 and 3.48 times as compared with the original TA substance, respectively.
Conclusion: The improvements of bioavailability and dissolution by encapsulating TA with HP-β-CD were effective.