Self-micellizing solid dispersion of cyclosporine A for pulmonary delivery: Physicochemical, pharmacokinetic and safety assessments.

The present study aimed to develop an inhalable self-micellizing solid dispersion of cyclosporine A (SMSD/CsA) for the direct delivery to the respiratory system with improved therapeutic efficacy and minimized systemic exposure. SMSD/CsA was obtained by wet-milling, and then jet-milled SMSD/CsA was blended with lactose carrier, producing a respirable powder of SMSD/CsA (SMSD/CsA-RP). The physicochemical, pharmacological, and pharmacokinetic properties of SMSD/CsA-RP were characterized, and the hepatotoxic and nephrotoxic potentials were investigated by biomarker analysis. Cascade impactor analysis demonstrated that SMSD/CsA-RP had high in vitro inhalation performance, with a fine particle fraction of 36%. In simulated lung fluid, the SMSD/CsA exhibited better dissolution behavior than amorphous CsA. Pretreatment with SMSD/CsA-RP resulted in significant suppression of antigen-evoked inflammatory events in rats. After intratracheal administration of SMSD/CsA-RP at a pharmacologically effective dose (100μg-CsA/rat), the AUC0-24 value was <1% of that after oral administration of Neoral® at a toxic dose (10mg-CsA/kg). Compared with oral Neoral®, insufflated SMSD/CsA-RP showed 99% reductions of CsA concentrations in both liver and kidney. No significant increases of biomarker levels in plasma were observed even after repeated intratracheal administration of SMSD/CsA-RP for 7days. From these findings, SMSD/CsA-RP might be a favorable dosage form for effective and safe inhalation therapy of CsA.