1577. Particle Characterization of Nebulized Liposomal Amphotericin B and Its Use in the Treatment of Murine Pulmonary Aspergillosis

BACKGROUND: Immunocompromised patients are very susceptible to pulmonary aspergillosis causing 50% mortality with present treatments, indicating a need for improved therapy. To address this, we standardized a nebulization method for effectively delivering liposomal amphotericin B (AmBisome®, AmBi) into lungs of Aspergillus fumigatus-infected mice. METHODS: AmBi particle characterization was done with a Cascade particle impactor and a Schuco S5000 nebulizer containing 1.33 mg/mL AmBi. For in vivo studies, AmBi was nebulized (neb) into a 12 compartment chamber (one mouse/compartment), following immunosuppression with 28 mg/kg triamcinolone IP (d-3, -1, +1). Mice were challenged d0 with 9 x 10(6)A. fumigatus (ATCC#13073) and 4 hours post-challenge, divided into 5 groups (n = 12/gp): 5 days of 20 min/day neb AmBi (Gp1), 5 days of 10 min/day neb AmBi (Gp2), 20 min/day neb AmBi days 0, 1, 3, 5, 7 (Gp 3), 5 days of intravenous(IV) AmBi 7.5 mg/kg/day (Gp4) and IV PBS (Gp5). Seven mice/gp were monitored for survival to d21 and lungs, livers, kidneys, spleens (5 mice/gp) analyzed for mean amphotericin B µg/g and CFU/g. RESULTS: 87% of neb AmBi particles were between 0.43 mm to 3.3 mm allowing for drug penetration into 1°, 2° and terminal bronchi, bronchioles, and alveoli. This resulted in very good protection, with 20 min daily neb treatments (Gp1) giving 100% survival and 10 min daily neb treatments producing 71% survival (Gp2). There were no survivors in the PBS gp (P < 0.02 vs. Gp1 and Gp2). Every other day neb AmBi or daily IV AmBi was less effective (43% survival). In addition, neb AmBi for 20 min (Gp1) yielded significantly lower fungal burden in lungs vs. all other AmBi treatments (P < 0.02). While drug was detected in lungs of mice given 20 min of neb AmBi (2.6 µg/g), there was no drug detected in livers, kidneys or spleens of any mice given neb AmBi. In comparison, with IV AmBi, drug was detected in the lungs (7 µg/g), livers (204 µg/g), kidneys (38 µg/g), and spleens (114 µg/g). CONCLUSION: Daily AmBi nebulization was an effective and potentially less nephrotoxic treatment for murine pulmonary aspergillosis since it achieved significantly lower tissue fungal burden and much better survival vs. daily IV AmBi, without delivering drug to the kidneys. DISCLOSURES: All authors: No reported disclosures.