Effects of transdermal scopolamine on pulmonary function, symptoms and bronchial hyperresponsiveness to methacholine

This study is a result of two consecutive double-blind, placebo-controlled, cross-over studies. In the first study, we evaluated therapeutic effects of a single transdermal scopolamine patch (Scopoderm(R) TTS, size 2.5 cm(2), Ciba Geigy) on forced expiratory volume in one second (FEV1), reversibility, peak expiratory flow (PEF) and symptoms in ten patients with reversible airways disease (Delta FEV1 greater than or equal to 9% predicted). During the study, blood and urine samples were taken from the patients and analysed for scopolamine levels. The drug was adequately taken up from the patch into the systemic circulation. However, no significant clinical effects, nor correlations between the scopolamine levels and the outcome parameters were observed. Because of the possibility of sub-therapeutic doses in the first study, a second study with two transdermal scopolamine patches was performed in ten patients with bronchial hyperresponsiveness to methacholine. The blood and urine concentrations of free scopolamine were doubled compared to the first study. There were still no statistically significant effects on FEV1, PEF, symptoms, and bronchial hyperresponsiveness, yet most of the patients now reported adverse side effects. We conclude that transdermal administration of scopolamine is not clinically useful in asthma and chronic obstructive pulmonary disease. Even application of two patches does not result in therapeutically effective levels at the muscarinic receptors in the lung, yet causes several side effects. (C) 1997 Elsevier Science B.V.