ABSTRACT
Clinical development of inhalation products has a long history, and promises to grow ever more diverse and challenging in the future. The popular pressurized metered dose inhaler (MDI or pMDI), which dates back to the 1950s, rapidly overtook the nebulizer to become the mainstay of delivering drug topically to the lung. By the late 1980s, however, there was a growing realization that the chlorofluorocarbon (CFC) propellants used in MDIs contributed to the depletion of the ozone layer as well as global warming, and would require replacement over time, as dictated by the Montreal Protocol. Nearly two decades later, the U.S. pharmaceutical industry has brought few non-CFC propellant products to market despite the substantial investment made in time and resources to do so. Increasing interest has turned to the invention and development of new inhaler technologies that avoid the need for propellant, such as dry powder delivery and new modes of nebulizing drug from handheld devices. Thus inhalation drug delivery technology has seen a renaissance in the past decade, and new start-up companies have proliferated to realize its fresh potential.
