Beta-adrenoceptor blockers and terbutaline in patients with chronic obstructive lung disease. Effects and interaction after oral administration

We studied the effects of a combined treatment with beta 2-stimulating and beta-blocking drugs in 35 patients suffering from chronic obstructive lung disease (COLD) and ischemic heart disease, and/or arterial hypertension. The drugs used were equipotent repeated oral doses of metoprolol (100 mg twice daily [bid]), propranolol (80 mg bid), and a matching placebo for beta-adrenoceptor blockade given in a double-blind and crossover fashion. The intake period of each beta-blocker was two days with consecutive two-day-washout period; 2.5 mg terbutaline and beta-stimulator placebo, respectively, were given throughout the whole trial three times daily (tid). Propranolol alone caused severe deterioration of lung function. After 18 patients had been studied, this drug had to be excluded from the trial. When compared with placebo, metoprolol provoked increasing obstruction, too, but to a significantly lesser degree than propranolol. These negative effects on FEV1 and FRC were completely equalized by terbutaline. Predictive factors for the tolerability of beta-blockers in patients with COLD could not be found. Therefore, careful observations in the initial phase of the treatment with beta-selective blockers are necessary.