Enhanced bioavailability of albendazole sulfoxide via binary solid dispersion: Preparation, characterization and goat...

Albendazole sulfoxide (ABZSO), the pharmacologically active metabolite of albendazole, exhibits favorable tissue distribution but its pharmaceutical application is constrained by poor aqueous solubility. In this study, an optimized binary solid dispersion (SD) of ABZSO was prepared by the fusion method using poloxamers P188 and P407 at an 8:1 ratio, with a drug-to-carrier ratio of 1:3. The optimized formulation achieved rapid drug release, with a cumulative dissolution of 99.39% within minutes, and increased the apparent solubility of ABZSO to 105 mg·L^-1. Solid-state characterization by differential scanning calorimetry, X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy demonstrated that ABZSO was present in a partially amorphous, mixed-phase state, with residual crystallinity semi-quantitatively estimated as 21.80% and 32.33% as determined by DSC and XRD, respectively. The optimized formulation showed acceptable batch-to-batch reproducibility and maintained acceptable short-term dissolution performance under stress conditions, although further optimization of long-term physical stability remains necessary. In a goat pharmacokinetic study, the ABZSO-SD significantly enhanced systemic exposure and achieved a relative oral bioavailability of 120.55% compared with the laboratory-prepared suspension (P < 0.01). Overall, these findings demonstrate that the optimized ABZSO-SD formulation effectively improves the solubility, dissolution performance, and oral absorption of ABZSO, providing a potential formulation strategy for enhancing ABZSO bioavailability in ruminants.