The efficacy of therapeutic aerosolized amphotericin B (AMB) was studied in a steroid-immunosuppressed murine model of invasive pulmonary aspergillosis. Nebulized liposomal AMB can be a valid approach to the treatment of this infection, with subjects showing significantly improved survival relative to that of subjects given intravenous deoxycholate AMB, as well as lower lung weights and pulmonary glucosamine levels.Pulmonary disease is the most frequent form of invasive aspergillosis (4), a fungal infection of growing incidence among immunocompromised patients (4), chiefly caused by Aspergillus fumigatus and associated with high mortality rates (10), despite a therapeutic arsenal that has been broadened with the approval of new drugs (5,7,15). To improve the poor results obtained with current treatment regimens, the potential usefulness of methods which may increase the concentration of amphotericin B (AMB) at the infectious focus, including its use by nebulization, has been suggested (8,16,19).The efficacy of nebulized deoxycholate AMB or liposomal AMB was compared to that of conventional intravenous (i.v.) dosages of both formulations, using a murine model of invasive pulmonary aspergillosis (IPA). The potential benefits of inhalation plus i.v. administration were also explored. This experimental protocol was approved by the Ethics Committee of Vall d'Hebron Hospitals.Female Wistar rats (180 to 200 g; Harland Iberica, Spain), fed with a low-protein diet, were immunosuppressed with 125 mg of subcutaneous cortisone acetate (Sigma Chemical Co., St. Louis, MO) per kg of body weight three times per week, from 14 days before infection to the end of the experiment (11).On day 0, animals were intratracheally challenged with 0.3 ml of a conidial suspension prepared from a 1-week-old subculture on Sabouraud dextrose agar of a clinical isolate of A. fumigatus (AF19/68). Conidia were counted in a hemocytometer and adjusted to 8 ϫ 10 6 cells/ml in sterile saline. Intravenous treatments were administered through a central venous catheter (11). Aerosols were generated by a CR60 compressor (Medic-Aid Ltd., West Sussex, United Kingdom; flow rate, 10 liter/min) attached to a Nebulizer II Oxinova (Carburos Metálicos, Barcelona, Spain) and were led through a nose-only exposure inhalation chamber (Panlab, Spain) over a 60-min period. The total dosage of AMB administered to each animal was calculated with the following formula: the total dosage ϭ the chamber concentration of AMB (mg/liter) ϫ the minute volume (liter/min) ϫ the duration of exposition (min) ϫ the animal's weight (kg Ϫ1 ) (1). The minute volume is equal to the body weight 0.75 (grams) ϫ 0.00254 (6). Animals were randomized to receive 5% dextrose i.v. Surviving rats were sacrificed 24 h after the last dose of treatment. All animals were aseptically dissected. Lungs were weighed and homogenized in sterile distilled water, and aliquots were serially diluted and plated onto Sabouraud dextrose agar for colony counts. Lung homogenates were processed for chitin assay, as des...