New propellant-free technologies under investigation

Interest in the use of solution inhalers and dry powder inhalers (DPIs) has increased in recent years, broadening from systems for the delivery of tra ditional respiratory medications to the delivery of inhaled proteins, pepti des, and analgesics. This has led to numerous developments and a range of i nhaler designs and technology, each with advantages and distinctive feature s. Novel devices for aerosolization of solutions can be broadly divided int o three main classes: adaptive aerosol delivery devices, metered dose liqui d inhalers (MDLIs), and breath-actuated nebulizers. Similarly, the wide ran ge of DPIs in development can be classified generally according to their me ans of storing and providing the drug, that is, as single capsules, a bulk reservoir, or multiunit-dose devices. Choice of a system for delivering a l iquid solution is based on a number of factors (e.g., ease of use, convenie nce, aerosol properties, dose delivery, and drug deposition), the combinati on of which will have an impact on the single most important factor: clinic al benefit. Ultimately, the patient must be able to use the device easily, maintain it, and derive clinical benefit from the drug delivered by the sys tem. Physicians and patients must recognize that if one system does not wor k, an alternative must be tried.