Recent Patents in Pressurised Metered Dose Inhalers
Affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK.
Keywords: Actuators, add-on devices, aerosol drug delivery systems, canisters, dose counters, monodisperse, pressurised metered dose inhalers, valves, Moisture Ingress, Suspension Formulations
In this paper recent patents in pressurised metered dose inhalers have been reviewed. The patents are related to novel valves, dose-counters, formulations, add-on devices, reduction of propellant leakage and inkjet technology. Recently patented dose-counters provide mechanisms that are less susceptible to inaccuracy, and are battery-less electronic dose-counters with the help of miniature electromechanical generators. Regarding the formulation aspect, recent patents provide methods for combinational pMDIs and more stable products. Advantages of recently patented valves are being spring-free and less subject to loss of prime. Recent developments in micromachining have allowed patents that incorporate inkjet technology to develop inhalers that are similar to pMDIs, but produce uniform aerosol droplets. Coating canisters with suitable polymers has reduced need for excipients. Recently patented add-on devices reduce aerosol deposition in the spacer by creating turbulence on the walls of the chamber. Blockage of nozzles in actuators is prevented by providing tapered nozzle channels. In conclusion, these patents show better understanding of pMDIs and provide methods to achieve products with much improved reliability, aerosol performance and stability.
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