Determination of the Distribution of Inhaled Drugs in Human Airways by Raman Spectroscopy

A novel Raman spectroscopic method has been developed to study the distribution of inhaled drugs and other airborn substances in human airway replicas. A drug from a metered dose inhaler was introduced into a realistic human respiratory tract prepared by 3D printing from computer tomographic data recorded on humans, and the deposited material was collected on silicon substrates fixed to the hollow airway’s walls. The analysis of the covered area was performed by mapping the characteristic Raman peak intensity of the drug over the substrate surface; the amount was determined by integration of the total intensity measured at different points. The Raman mapping method was verified by comparison with optical microscopic images of the same surface area.