Surface properties of lactose carriers and their effect on drug delivery of dry powder inhaler

Abstract

Dry powder inhaler (DPI) is generally formulated by mixing micronized drug particles with larger carrier particles. The performance of DPI is affected by the carrier surface roughness. Scanning probe microscopy (SPM) is increasingly employed to assess surface roughness. In this study, topographical data were obtained from the 3D profiles of the particles and surface roughness quantified using different parameters. The SPM operation settings were optimized and the sensitivity of the different roughness parameters obtained was investigated. Scanning electron microscopy and Brunauer, Emmett and Teller adsorption technique were also employed for comparison. Each of these methods has its advantages and limitations. It was found that a combination of roughness parameters might be necessary to describe the surface roughness pattern of the carrier. From these findings, roughness models were proposed to describe the surface morphology of carrier particles and its influence on drug deposition from DPI formulations.