Preparation, characterization and pharmacokinetic studies of sulfobutyl ether-β-cyclodextrin-toltrazuril inclusion complex

Abstract In present study, a novel formulation was developed to enhance solubility, stability, and bioavailability of toltrazuril (Tol). Tol is a highly effective, broad-spectrum, low-toxic triazinone anticoccidial drug, but has poor water solubility. The inclusion complex of Tol with sulfobutyl ether-β-cyclodextrin (SBE-β-CD-Tol) was prepared by freeze-drying method and characterized via Infrared Fourier transformation (FTIR), Differential scanning calorimetry (DSC), Powder X-ray diffractometry (XRD), Scanning electron microscopy (SEM), and 1H NMR measurements. The comparative pharmacokinetic studies of Tol or SBE-β-CD were conducted by a single orally administered dose of 10 mg/kg in chickens to provide parameters for clinical applications. As a result, 1H NMR analysis showed that Tol may be embedded in the cavity of SBE-β-CD to form a stable inclusion complex. In addition, the stoichiometry obtained by the phase solubility study was 1:1. Moreover, the pharmacokinetics results showed that the SBE-β-CD-Tol exhibited higher absorption rate, prolonged the time of in vivo retention, and possessed better bioavailability relative to those of Tol. The present study revealed that the new SBE-β-CD-Tol can provide a practical and economical option for improving the solubility, stability and bioavailability of Tol.