Novel Docetaxel-Loaded Micelles Based on all-trans-Retinoic Acid: Preparation and Pharmacokinetic Study in Rats

Docetaxel (DTX) is a poorly soluble drug. The purpose of this study was to explore a DTX-loaded micelle delivery system using N-(all-trans-retinoyl)-L-cysteic acid methyl ester sodium salt (XMeNa) as the carrier materials. In this study, amphiphilic surfactant XMeNa was synthesized. Then, the blood biocompatibility and the value of critical micelle concentration (CMC) were assessed by a hemolysis test and pyrene-based fluorescent probe techniques, respectively. The XM-DTX micelles were prepared using the method of thin-film hydration, and characterized by dynamic light scattering and transmission electron microscopy (TEM). The entrapment efficiency (EE) and drug loading efficiency (DLE) were assessed by the ultrafiltration method. In vitro release and pharmacokinetic behaviors of XM-DTX micelles were performed in rats using Taxotere (a commercialized DTX injection) as a control. Our data confirmed the excellent blood biocompatibility of XMeNa as a carrier. XMeNa can self-assemble into micelles in aqueous media with a very low CMC (6.2 μg/mL). The average size and zeta potential of the XM-DTX micelles were 17.3 ± 0.2 nm, and −41.6 ± 0.3 mV, respectively. EE and DLE reached up to 95.3 ± 0.7% and 22.4 ± 0.2%, respectively, which may account for the high solubility of DTX in normal saline. The micelles were spherical in TEM with good dispersion and no aggregation and adhesion, and exhibited good stability after reconstitution over 8 hours. Results from in vitro release assay suggested a much slower release behavior of XM-DTX micelles in comparison to Taxotere. Additionally, XM-DTX micelles prolonged DTX retention in blood circulation, increased the area under the curve by 2.4-fold, and significantly decreased the clearance of the drug. Given above, the XM-DTX micelles could improve the solubility and the release of DTX. The amphiphilic surfactant XMeNa also exhibited great potential as a vehicle for exploring delivery of poorly water soluble drugs in the future.