Abstract: An endotracheal catheter assembly and method for deep intrapulmonary, aerosol delivery of liquid drugs and other liquid therapeutic agents. The invention can deliver a bolus dose of liquid drugs into the lungs of a patient which is at least bioequivalent in terms of physiological effect to a similar drug dose delivered intravenously. The catheter assembly includes a first, gas-bearing tube and a second, liquid bearing tube, preferably concentrically nested within the gas-bearing tube. The tubes are inserted in an airway of the patient, preferably by threading the tubes into a lumen of an endotracheal tube, to position a terminal nozzle formed by distal tips of the tubes near a carina of the patient. At the nozzle, the lumen of the first tube has a comparative cross-sectional area relative to that of the second tube's lumen of between about 0.4:1.0 and 4.0:1.0.