Liquid drug cartridges and an associated inhaler are used to deliver one more separate doses of an aerosolized liquid drug. A cartridge includes a container for storing the liquid drug, an end cap having an ejection opening, a filter element, and a piston that is repositionable relative to the container to selectively eject a volume of liquid drug from the ejection opening. The filter element filters the liquid drug prior to ejection from the ejection opening. The liquid drug cartridge can be coupled with an inhaler that includes an aerosol generator. The aerosol generator includes a vibratable membrane onto which the liquid drug is ejected. The liquid drug is aerosolized by the vibration of the membrane for inhalation by a user.
