A device for delivering a drug by inhalation is disclosed. The device includes a body defining an interior flow-through chamber having upstream and downstream chamber openings, and a drug supply unit contained within the chamber for producing, upon actuation, a heated drug vapor in a condensation region of the chamber. Gas drawn through the chamber region at a selected gas-flow rate is effective to form drug condensation particles from the drug vapor having a selected MMAD between 0.02 and 0.1 MMAD or between 1 and 3.5 gm. A gas-flow control valve disposed upstream of the unit functions to limit gas-flow rate through the condensation region to the selected gas-flow rate. An actuation switch in the device activates the drug-supply unit, such that the drug-supply unit can be controlled to produce vapor when the gas-flow rate through the chamber is at the selected flow rate.