The present invention relates to a drug delivery system comprising: a chamber including an air inlet and an air outlet and defining an air path from the air inlet to the air outlet； and a dose metering system formed into the walls of the chamber to assist in drug dispersion into the air path； a reservoir in proximity to the dose metering system and configured to retain a drug to be dispersed into the air path； and wherein the dose metering system is designed to divert, deflect or direct at least a portion of airflow from the chamber into the reservoir.
