Spray-Dried Formulations of Relaxin-H2 for Inhalation

To develop an inhaled formulation of relaxin-H2 that achieves sustained concentrations of protein above 10 ng/mL in serum and epithelial lining fluid over 24 h, thereby enabling chronic administration of the medicine at home.

Dry powder formulations of relaxin-H2 were prepared by spray drying an aqueous feedstock comprising protein in sodium acetate buffer. The physicochemical properties and aerosol performance of the powder were assessed using standard methods for inhaled dry powders. The pharmacokinetics of relaxin-H2 was assessed in rats following intratracheal administration and in dogs following administration by oral inhalation.

The spray dried powder was comprised of fine corrugated particles. The amorphous dry powder was stable for a period of at least two years at room temperature, with low formation of iso-Asp and oligomers on storage. Process optimization enabled a high total lung dose (> 90% w/w) to be achieved following administration with a portable dry powder inhaler. Following intratracheal administration of a 500 μg/kg dose of relaxin-H2 to rats or inhaled administration of the same dose to dogs, the relaxin-H2 serum and bronchoalveolar lavage fluid concentrations were maintained above 10 ng/ml over 18-24 h, with a high absolute bioavailability.

Dry powder formulations of relaxin-H2 may provide a noninvasive delivery technology enabling chronic administration of the pleiotropic hormone for both local lung and systemic applications.