Bronchodilating effect and side effects of beta2- adrenoceptor stimulants by different modes of administration (tablets, metered aerosol, and combinations thereof). A study with salbutamol in asthmatics.

Effects and side effects of an adrenergic beta2-stimulant (salbutamol) given by mouth and by inhalation from a metered aerosol were compared. Cumulative dose-response curves for both routes of administration concerning 1-sec forced expiratory volume, forced vital capacity, heart rate, blood pressure, and tremor were constructed. Tremor was found to be the dose-limiting side effect with both modes of administration. The metered aerosol in doses as large as 0.6 mg was shown to produce a greater increase in the 1-sec forced expiratory volume, with fewer side effects than could be achieved with tolerable doses of salbutamol by mouth. An oral dose of 6 mg is probably the maximal tolerable dose in most cases. Oral treatment seems to have a better effect than inhalation treatment on the forced vital capacity at the same effect on 1-sec forced expiratory volume, possibly due to a better effect on small peripheral airways. The effect of combining different oral doses of salbutamol with inhaled salbutamol was also studied. A very good additional effect of inhalations given after 4 and 6 mg by mouth was shown.