Use of gamma scintigraphy to evaluate the performance of new inhalers

Many new inhaler devices and formulations involving pressurized metered dose inhaler (pMDI), dry powder inhaler (DPI), and liquid spray technologies are currently being developed. Some of these novel drug delivery products deposit a greater percentage of the drug dose in the lungs than a conventional chlorofluorocarbon (CFC)-based pressurized aerosol, hence providing better drug targeting to the required site of drug action. The noninvasive imaging technique of gamma scintigraphy provides an accurate quantification of the amount of drug deposited in the lungs from inhaler devices together with an assessment of deposition in different lung regions. Respimat (Boehringer Ingelheim, Ingelheim am Rhein, Germany) is a novel liquid spray "soft mist inhaler" that more than doubles deposition in the lungs compared with a pMDI and reduces oropharyngeal deposition, thus providing a degree of drug targeting comparable to that from a spacer device. These data suggest that Respimat should be a valuable addition to the range of devices available for inhalation therapy.