Exploration of supersaturable lacidipine ternary amorphous solid dispersion for enhanced dissolution and in vivo absorption.

Amorphous solid dispersion stands out among different formulation strategies for the improvement of dissolution rate and bioavailability via generating supersaturated drug solution, which provides a higher solubility than the crystalline counterpart, leading to a promoted intestinal absorption. Soluplus (SOL), termed as the fourth generation of solid dispersion carrier, presented a preferable effect on supersaturation maintaining and bioavailability enhancement for poorly water soluble drugs. However, some binary drug/SOL systems still suffer from insufficient dissolution and unsatisfied in vivo absorption. Thus, taking Lacidipine (LCDP) as a model drug, the aim of this study was to explore a ternary amorphous solid dispersion consisted of SOL and a surfactant to further increasing the dissolution rate and in vivo absorption. First of all, various surfactants were screened via equilibrium solubility enhancement and sodium dodecyl sulfate (SDS) was selected as the most effective candidate. Thereafter, the influence of SOL/SDS and drug/carrier weight ratio on the supersaturation maintaining was investigated. The supersaturated drug solutions were spray dried and the in vitro release, pharmacokinetic behavior as well as physical stability were investigated. It was found that although combination use of SOL and SDS did not present remarkable advantage in supersaturation maintenance in liquid state, 6-7 times higher dissolution rate under non-sink condition was noticed at SOL/SDS ratio 3:1 after spray drying, for LCDP/SOL/SDS based formulation compared to that of the binary LCDP/SOL system, which was maintained even after 92.5% humidity and 60 °C accelerated stability test. Moreover, compared to the LCDP/SOL formulation, approximately 3.3 and 3.7-fold increase in C and AUC was achieved with LCDP/SOL/SDS based formulation. In conclusion, the presented SDS could not only be regarded as solubility enhancer but also dissolution or bioavailability promoter, highlighting its potential application in ternary supersaturable amorphous solid dispersion for further increasing the dissolution and in vivo absorption of poorly water soluble drugs.