Optimal inhalation procedure for the fenoterol powder inhaler.

To assess the optimal inhalation procedure of a fenoterol (Berotec) powder inhaler, the degree of reversibility of lung function impairment was studied in 10 patients with stable asthma after 1) deposition of 0.2 mg fenoterol under the tongue, 2) a rapid inhalation from residual volume (RV) to total lung capacity (TLC), and 3) a slow inhalation from functional residual capacity (FRC) to TLC. There was no effect on FEV1 of depositing fenoterol under the tongue, but both inhalation menoeuvres improved FEV1 significantly (p less than 0.01) and the rapid inspiration manoeuvre even slightly more (p less than 0.05) than the slow. It is concluded that the problem of impaction of large particles in the mouth and pharynx following rapid inhalation from a conventional pressurized cannister is considerably reduced with the fenoterol powder inhaler, due to the resistance it causes which tend to automatically reduce a forced inspiration flow rate to optimal low values.