Regional lung deposition of a technetium 99m-labeled formulation of mometasone furoate administered by hydrofluoroalkane 227 metered-dose inhaler

Background: A new inhaled suspension formulation of mometasone furoate (MF) , a potent corticosteroid with minimal systemic availability, has been deve loped for the treatment of asthma. This formulation is delivered by metered -dose inhaler (MDI) using the nonchlorofluorocarbon propellant hydrofluoroa lkane 227 (HFA-227). Objective: The primary goal of this study was to determine the respiratory tract deposition of this formulation of MF. A secondary objective was to me asure plasma concentrations of MF and a putative metabolite, 6-beta -OH MF, to determine the systemic exposure to corticosteroid. Methods: This was a single-dose, open-label study in which 200 mug of techn etium 99m (Tc-99m)-radiolabeled MF was administered to patients with asthma . Gamma scintigraphy was used to quantify lung, oropharyngeal, stomach, and MDI mouthpiece deposition patterns of ME Results: Eleven patients, aged 21 to 47 years, with a history of asthma wer e enrolled in and completed the study. The mean (+/- SD) whole lung deposit ion of MF was 13.9% +/- 5.7% of the metered ex-valve dose. The central lung zone received 5.3% +/- 2.8% of the dose; the intermediate zone received 4. 7% +/- 1.9%; and peripheral lung deposition was 4.0% +/- 1.5%. The mean (+/ - SD) ratio of peripheral to central lung deposition was 0.8 +/- 0.2. Oroph aryngeal deposition was 79.1% +/- 8.7% of the ex-valve dose, with 6.3% +/- 7.8% deposited on the MDI mouthpiece and 0.7% +/- 0.5% exhaled. The majorit y of plasma samples taken for analysis of MF and 6-beta -OH MF concentratio ns were below the limit of quantification (50 pg/mL) in all patients after inhalation of 200 mug Tc-99m-labeled MF. Conclusion: The lung deposition of MF when administered via HFA-227 MDI is comparable to the 10% to 20% lung deposition seen with other corticosteroid suspension for mulations administered by MDI that have demonstrated effect iveness in the treatment of asthma.