Purpose: To compare the systemic delivery of deslorelin following intratracheal administration of different deslorelin formulations. The formulations included dry powders of deslorelin, large-porous deslorelin-poly(lactide-co-glycolide) (PLGA) particles, and small conventional deslorelin-PLGA particles. Also, solution formulations of deslorelin and deslorelin-hydroxy-propyl-beta-cyclodextrin (HPbetaCD) complexes were tested.
Methods: Dry powders of deslorelin, large-porous (mean diameter, 13.8 microm; density, 0.082 g/cc), and small conventional (mean diameter, 2.2 microm; density, 0.7 g/cc) deslorelin-PLGA particles and solutions of deslorelin with or without HPbetaCD were administered intratracheally to Sprague-Dawley rats. Blood samples were collected at 3 h, 1, 3, and 7 days postdosing, and plasma deslorelin concentrations were determined using enzyme immunoassay. At the end of 7 days, lungs were isolated, and bronchoalveolar lavage fluid was collected and analyzed for deslorelin.
Results: At the end of 7 days, deslorelin plasma concentrations in the large-porous deslorelin-PLGA particle group were 120-fold and 2.5-fold higher compared to deslorelin powder and small conventional deslorelin-PLGA particles, respectively. Co-administration of HPbetaCD resulted in 2-, 3-, and 3-fold higher plasma deslorelin concentrations at 3 h, 1 and 3 days, respectively, compared to deslorelin solution. On day 7, deslorelin concentrations in bronchoalveolar lavage fluid as well as plasma were in the order: large porous particles > small conventional particles > deslorelin-HPbetaCD solution > deslorelin powder > deslorelin solution.
Conclusions: Large-porous deslorelin PLGA particles can sustain deslorelin delivery via the deep lungs. Co-administration of HPbetaCD enhances the systemic delivery of deslorelin. The pulmonary route is useful as a noninvasive alternative for the systemic delivery of deslorelin.