Nifedipine – a Calcium Channel Blocker – in Asthmatic Patients Interaction with Terbutaline

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Abstract
Seven asthmatic patients were studied in a single-blind randomized, crossover study after oral administration of 20 mg nifedipine or placebo. Four increasing doses of i.v. terbutaline were then given with 30 min interval. The study was concluded with inhalation of 5 terbutaline puffs. FEV1 [forced expiratory volume in 1 s] measurements 30 min after intake of nifedipine did not show any difference compared to placebo. During the terbutaline treatment there was a more pronounced bronchodilation after nifedipine than after placebo (P < 0.05). Terbutaline-induced skeletal muscle tremor was similar after nifedipine and placebo pretreatments. After nifedipine intake there was a decrease of diastolic blood pressure and a reflexogenic tachycardia. Thus, this study showed a small potentiation of the .beta.2-adrenoceptor mediated bronchodilation, which is of importance when treating patients with simultaneous asthma and hypertension or angina pectoris.