In-line assessment of pulmonary drug delivery using light obscuration

A candidate optical technology for characterisation of the value and quality of the drug dose delivered to a patient from an inhaler is examined. The theoretical reasoning behind the design of this technology is presented with reference to the optical scattering of the drug cloud. A technical implementation is presented; based upon the light obscuration signature, observed in the delivery path during drug delivery. Dose evaluation studies are reported, performed on different types of drug formulations using regulatory testing procedures and the proposed optical sensing system. Further applications of this technology are discussed in relation to the identification and evaluation of inhaler-drug formulation combinations, which are most suitable for particular patients.