The effect of formoterol over 24 h in patients with asthma: the role of enantiomers
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The single-dose effect of formoterol racemate and enantiomers on bronchodilatation up to 24 h was determined. Forty-six reversible asthmatic patients were randomised to this double blind, crossover study. Formoterol was inhaled by nebulizer (HaloLite(R)); 4.5 and 36 mug of the racemate (rac-formoterol), 2.25 and 18 mug of (R;R)-formoterol, 18 mug of (S;S)-formoterol, or placebo. Airway and systemic effects were assessed by serial measurements of forced expiratory volume during the first second, FEV1 (24 h), and heart rate (4 h). Rac- and (R;R)formoterol significantly and dose-dependently increased FEV1, with similar mean maximal effect. (S;S)-formoterol was without significant effects on FEV1 and heart rate. (R;R)- and rac-formoterol were still effective 22-24 h after single high doses, but this was associated with some systemic side effect (increased heart rate) initially. Average 22-24 h FEV1 was 8% (rac-formoterol 36 mug) and 11% ((R-R)-formoterol 18 mug) over placebo, respectively. No significant differences in effects were observed between rac- and (R;R)-formoterol. Thus, the single dose bronchodilatating effect of formoterol resides in (R;R)-formoterol. This study does not indicate a clinically important advantage of (R;R)-formoterol as acute bronchodilator compared to the racemate.
|Research areas and keywords||
Subject classification (UKÄ)
|Journal||Pulmonary Pharmacology & Therapeutics|
|Publication status||Published - 2005|