Abstract

Pathophysiological studies have shown that the alveolocapillary transfer of small solutes is much faster in healthy smokers than in non-smokers. The effects of smoking on the pulmonary absorption of inhaled terbutaline were examined in normal subjects. Nine healthy smokers and 13 healthy non-smokers inhaled nebulised terbutaline and dry terbutaline powder on two study days. Plasma concentrations of terbutaline were measured up to 240 minutes after the inhalation. The plasma concentration of terbutaline rose much faster in smokers than in non-smokers, the mean time to peak terbutaline concentration being 17 minutes in the smokers and 50 minutes in the non-smokers. The peak plasma concentration was nearly twice as high in the smokers as in the non-smokers, being 21 mmol/l and 23 mmol/l for the dry powder inhalation and nebuliser respectively in the smokers and 12 mmol/l and 14 mmol/l in the non-smokers. It is concluded that smoking increases the rate of terbutaline absorption and the peak plasma concentration achieved. The rapid pulmonary absorption of terbutaline in smokers may affect the onset of action of the drug and the duration of its therapeutic effects.