To improve the oral bioavailability of nanocrystalline drug preparations, the cationic 12-3-12 quaternary ammonium surfactant gemini was introduced into nanocrystals as a novel gastrointestinal bioadhesive material. Coenzyme Q10 (CoQ10), a typical Biopharmaceutics Classification System (BCS) class II drug, was used as a model drug. The 12-3-12 gemini surfactant was added to the preparation at a low concentration and imbued the particles with abundant positive charges. In vitro and in vivo gastrointestinal adhesion tests confirmed that the gemini-modified nanocrystals were prone to adhere to the upper gastrointestinal tract (GIT), thereby prolonging retention time in the GIT and enhancing absorption. In the distribution study in rats, the use of nanocrystals modified with gemini led to greater drug distribution to the heart and the liver than that achieved with the naked nanocrystals. A pharmacokinetic study in beagle dogs showed that the gemini-modified CoQ10 nanocrystals improved the oral bioavailability of CoQ10 in a dose-dependent manner, and the smaller size produced a much better effect with the same gemini modification. These results demonstrate that the cationic surfactant gemini is a promising oral bioadhesive material with applications in nanoscale drug delivery systems.
Keywords: Bioadhesive material; coenzyme Q10; drug delivery system; gemini; nanocrystal; oral bioavailability.