Strategic application of self-micellizing solid dispersion technology to respirable powder formulation of tranilast for improved therapeutic potential.

ABSTRACT

PURPOSE: The present study aimed to develop an inhalable self-micellizing solid dispersion of tranilast (SMSD/TL) using poly[MPC-co-BMA] to improve the therapeutic potential and safety. METHODS: The safety of poly[MPC-co-BMA] in lungs was assessed using rat lung epithelium-derived L2 cells. SMSD/TL and respirable powder of SMSD/TL (SMSD/TL-RP) were prepared using a wet milling system and jet mill, respectively. The physicochemical properties of TL formulations were characterized in terms of dissolution, morphology, and particle size. Pharmacological and pharmacokinetic studies were also conducted on inhaled SMSD/TL-RP. RESULTS: The lactate dehydrogenase level from L2 cells treated with poly[MPC-co-BMA] was lower than that with polysorbate 80, a positive control. SMSD/TL showed enhanced dissolution behavior of TL. The jet milled SMSD/TL particles easily separated from the lactose carrier, and the particle size was suitable for inhalation. Compared with RP of TL, inhaled SMSD/TL-RP (100 µg-TL/rat) could more strongly suppress the inflammatory responses in antigen-sensitized rats. The TL level in plasma after intratracheal administration of SMSD/TL-RP at a pharmacological effective dose (100 µg-TL/rat) was ca. 4.2-fold lower than that after oral administration of TL solution at a clinical dose (1.67 mg/kg). CONCLUSION: SMSD/TL-RP might be an attractive dosage form to improve the anti-inflammatory effects and safety of TL.