Abstract
We have investigated the influence of a valved holding chamber device (CD) on the cardiovascular effects of the beta 2 adrenergic agonist fenoterol, when administered from a metered dose inhaler (MDI). On two separate occasions eight healthy volunteers inhaled doses of 400, 600 and 800 ug fenoterol at 15 minute intervals (total dose 1800 ug) administered by MOI with or without a CD. Measurements of systolic time intervals, QT interval and blood pressure were obtained at baseline and 5 minutes after each inhalation. The CD significantly reduced the cardiovascular effects of fenoterol by MDI alone, in particular the direct inotropic responses as measured by a decrease in electromechanical systole (QS2I; −16.4 ms vs −35.5 ms, p <0.0001), QT/QS2 ratio (0.08 vs 0.13, p <0.001) and systolic blood pressure (1.4 mmHg vs 12.9 mmHg, p <0.0007). We conclude that the use of a CD reduces the inotropic effects that occur following administration of high doses of fenoterol by MDI.
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