An HFA 227-based metered dose inhaler containing furosemide coated with lecithin

Furosemide was coated with lecithin and the resulting material was used for the formulation of an MDI consisting of HFA 227 without cosolvents. The lecithin coating did not affect the SEM observation. The furosemide content of the lecithin-coated furosemide was in agreement with that calculated from the amounts of furosemide and lecithin used. In the case of MDI containing uncoated furosemide, the amount released depended both on the sequential actuations and daily use. On the other hand, the amounts released from the MDI containing the lecithin-coated furosemide were stable under all circumstances. Continuous leakage was observed for the MDI containing uncoated furosemide when five actuations were carried out before storage. In the case of the MDI containing lecithin-coated furosemide, no leakage of propellant after actuation was observed. These results suggest that the lecithin coating is useful for stable release and avoidance of leakage of propellant after actuation. HFAs-based MDIs without cosolvents could be developed using this technology.