Characterization of a cyclosporine solid dispersion for inhalation

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Pulmonary Medicine

Background:

• Lung transplant recipients often require immunosuppressive therapy with cyclosporine A (CsA).
• Effective delivery of CsA to the lungs is crucial for local treatment and minimizing systemic side effects.
• Developing respirable formulations for inhaled drugs presents significant challenges.

Purpose of the Study:

• To develop and characterize an inulin-based solid dispersion of cyclosporine A (CsA) suitable for inhalation.
• To evaluate the physicochemical properties, dissolution behavior, and aerosol performance of the developed solid dispersion.
• To assess the potential of this formulation for local treatment in lung transplant patients.

Main Methods:

• Solid dispersions of CsA in inulin were prepared using spray freeze-drying.
• Characterization included water vapor uptake, specific surface area, particle size analysis, and Fourier transform infrared spectroscopy (FTIR).
• Dissolution behavior and aerosolization properties (emitted fraction, respirable fraction, fine-particle fraction) were evaluated.

Main Results:

• The spray freeze-drying process yielded powders with high specific surface areas (~160 m²).
• The solid dispersion exhibited a combination of solid solution and solid suspension characteristics, varying with CsA drug load.
• The powder demonstrated excellent aerosol dispersion with a high emitted fraction (95%) and respirable fraction (75%).
• Dissolution rates were enhanced compared to a physical mixture, with inulin dissolving faster than CsA.

Conclusions:

• The developed inulin-based CsA solid dispersion is a promising respirable powder for inhalation.
• Spray freeze-drying with inulin effectively increased the specific surface area and wettability of CsA.
• The formulation's characteristics suggest suitability for the local treatment of lung transplant patients.