BACKGROUND An earlier study documented that, in patients with chronic obstructive pulmonary disease (COPD), addition of ipratropium bromide at the clinically recommended dose (40 μg) does not produce any further bronchodilation than that achieved with salmeterol 50 μg alone. However, the dose of ipratropium bromide needed to produce near maximal bronchodilation is several times higher than the customary dosage. The full therapeutic potential of combined salmeterol plus an anticholinergic drug can therefore only be established using doses higher than those currently recommended in the marketing of these agents. A study was undertaken to examine the possible acute effects of higher than conventional doses of an anticholinergic agent on the single dose salmeterol induced bronchodilation in patients with stable and partially reversible COPD.

RESULTS Salmeterol induced a good bronchodilation (mean increase 0.272 l; 95% CI 0.207 to 0.337) two hours after its inhalation. Oxitropium bromide elicited an evident dose-dependent increase in forced expiratory volume in one second (FEV₁) and this occurred also after pretreatment with salmeterol with a further mean maximum increase of 0.152 l (95% CI of differences 0.124 to 0.180).

CONCLUSIONS This study shows that acute pretreatment with 50 μg salmeterol does not block the possibility of inducing more bronchodilation with an anticholinergic agent when a higher than normal dosage of the muscarinic antagonist is used.