Influence of carrier surface fines on dry powder inhalation formulations

Abstract

Background: The performance of carrier-based dry powder inhalation formulations strongly depends on particle interactions between the drug and the carrier. Among other factors like particle size and shape, surface properties of the interacting partners play a decisive role. This study aims at investigating the effect of carrier surface characteristics on the in vitro deposition of ordered mixtures containing salbutamol sulfate as a drug and lactose and mannitol as model carrier compounds. Methods: The wet decantation method was used to remove the carrier fines adhered to the carrier surface and to obtain smoother carrier surfaces. In vitro deposition was investigated using the Next Generation Impactor. Results: In comparison to the formulations containing untreated carriers, the removal of carrier fines by wet decantation leads to a reduced in vitro deposition. This is possibly caused by an increase in the surface smoothness and an increase in the number of high energetic spots.

Keywords:

• Dry powder inhaler
• lactose
• mannitol
• salbutamol sulfate
• surface modification
• wet decantation