Twenty-six patients with mild to moderate asthma were enrolled in a doubleblind, randomised, cross-over study. Bronchial response to provocation, given as isocapnic hyperventilation with cold air (IHCA), was measured before and after one week's medication with single isomer R-salbutamol and racemic R/S-salbutamol, respectively. Doses of 0.63 mg R-salbutamol or 1.25 mg R/S-salbutamol were inhaled by nebuliser three times daily dming medication-weeks. Impulse oscillometry (IOS) as well as forced expiratory volume dming one second (FEV1) were methods used to identify bronchial response to provocation. Two patients withdrew from the investigation due to side-effects, one from Rthe other from R,S-salbutamol.
The aim of this study was to investigate the effects from medication with R,S- and R-salbutamol on bronchial response to provocation.
Intra-individual differences of < 2% between days in baseline values, measured as total airway resistance (R5) by IOS and ≤ 1% measured as FEV1. indicated comparable resting bronchial conditions. After a week's medication no significant differences in airway responsiveness to provocation could be demonstrated irrespective of the medication used.
Neither regular medication with inhaled corticosteroids up to 800 mg/day nor any increase in ahway inflammation, was found to influence the results.
Plasmaconcentrations of R-salbutamol were intra-individually lower after R- than after R,S-salbutamol. Considerable amounts of S-salbutamol were retrieved in plasma after medication with pure R-salbutamol.
We conclude that we were unable to demonstrate favourable effects of R-salbutamol over R,S-salbutamol regarding response to provocation with cold air after medication of one week's duration.