Jan Anders Roland Andersson

Fraction of dose exhaled after administration of pressurized inhalation aerosols

Abstract After the administration of a pressurized inhalation aerosol, a fraction of the dose will be lost with the exhaled air. In the present study suspension aerosols containing a freely water-soluble drug, terbutaline sulphate, and a practically insoluble drug, budesonide, were administered to 10 healthy subjects. The air flow rate, the tidal volume, and the moment of actuation were registered for each of the inhaled doses. The exhalation was performed without any breath-holding pause. The drug in the exhaled air was collected on a membrane filter and in an absorbing solution. The fraction of the dose lost with the exhaled air was less than 1% for both drugs. Differences in air flow rate and tidal volume did not affect the results. A particle growth due to moisture absorption did not appear to be important for the total drug deposition in the respiratory tract

Mode of inhalation for trained and untrained asthmatics using a pressurized aerosol

A pressurized inhalation aerosol should be actuated at the beginning of a slow and deep inhalation, followed by a long pause of breathholding. In this study a registration was performed on the mode of inhalation. The flow-volume curve and the moment of actuation were obtained from an aerosol actuator provided with sensors, and the breathholding pause was measured. Data were obtained from 34 asthmatic patients, regularly trained to use the pressurized aerosol, and these data were compared with those from 44 untrained patients. When the subjects used a terbutaline sulfate aerosol in their usual fashion, most of the trained subjects succeeded well. Further improvements could possibly be made regarding the depth of inhalation and, after control with the recording device, regarding the flow rate at actuation. Most of the untrained subjects did not use a deep enough inhalation with respect to their vital capacity, and their breath-holding pause was very short. It only seems possible to improve these parameters by regular training. In order to reach optimal results the asthmatic patients must be regularly controlled and instructed regarding their use of a pressurized inhalation aerosol. A recording device is useful in demonstrating to each subject which parameter can be improved.