Improvement of Antialveolar Echinococcosis Efficacy of Albendazole by a Novel Nanocrystalline Formulation with Enhanced Oral Bioavailability.

Alveolar echinococcosis (AE) is a chronic infectious parasitic disease that is fatal and still being neglected. Currently, the AE treatment recommended by the WHO is complete excision of the lesions, followed by the oral administration of albendazole (ABZ), the only effective first-line anti-AE drug, for two years. Unfortunately, complete excision of AE lesions is impossible in most cases, leaving the long-term use of ABZ as the only alternative. However, only about one-third of patients experience complete remission or cure with such treatments, largely because of the low oral bioavailability of ABZ caused by its very low solubility. To improve the oral bioavailability of ABZ, a novel nanocrystalline (NC) formulation of ABZ was obtained by spray-drying ABZ with a triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Poloxamer 188), and its physical structure was confirmed by scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXRD), and polarized optical microscopy (POM). The significantly reduced ABZ crystallite size coupled with prolonged ABZ supersaturation significantly improved the drug dissolution performance compared with that of the commercial ABZ oral product (Albenda), and the NC formulation showed an approximately 4.2-fold higher AUC than Albenda in a pharmacokinetic comparison in Beagle dogs as measured by the plasma concentration of albendazole sulfoxide, the active antiparasitic metabolite. Even more encouragingly, after 30 days of once-daily oral administration of the NC and Albenda formulations to SD rats with hepatic alveolar echinococcosis, the NC formulation demonstrated a cyst inhibition effect 3.7-fold greater than that of Albenda. We therefore conclude that the NC formulation could potentially be developed into an improved anti-AE drug therapy.