Global illumination Raman chemical imaging of a combination of two drug molecules in a dry powder inhaler formulation

Abstract

Isolated particles of a combination dry powder inhalation blend consisting of a lactose carrier and two Active Pharmaceutical Ingredients (APIs) are imaged by a global illumination Raman instrument. The imaged APIs individually adhere on the surface of large particles of lactose or appear as aggregates of smaller particles. This is probably the first Raman report describing the visualization of API particles on the surface of lactose carriers and also on the use of the global illumination Raman imaging platform on a dry powder inhalation blend. Two methods of dispersing particles for imaging are described: using a particle sizing instrument (mechanical dispersion), which achieves high dispersion, or manually (lightly) dispersing the powder with a spatula so as to minimize the perturbation of the API deposits. Both APIs are clearly identified in the chemical images although the key band of one of them interferes with the bands of lactose which negatively affects the background of the corresponding images. The method of dispersion is found to have a profound effect on the API deposits because the mechanical dispersion leads to complete separation of lactose and API particles previously adhered to its surface. The results presented here reveal the significant potential of this imaging hardware for fast and reliable visualization of the inhalation blends.