Effects of nifedipine on diffusing capacity and pulmonary capillary blood volume in chronic obstructive pulmonary disease. A controlled study.

The acute dose-dependent effects of nifedipine on the pulmonary diffusing capacity for CO and other lung function indices were investigated in patients with chronic obstructive pulmonary disease (COPD) in a randomized double-blind, cross-over, placebo-controlled trial. Seventeen successive, clinically stable, moderate COPD patients with pulmonary hypertension and 15 control subjects were included in the study. The diffusing capacity of the lungs for carbon monoxide (DLCO) was measured with the single-breath method. Nifedipine (10 and 20 mg) and placebo were administered sublingually at room air. Nifedipine (10 and 20 mg) increased DLCO and DLCO/alveolar volume; however, a larger effect was observed with 10 mg. In addition, nifedipine increased the pulmonary capillary blood volume dose-dependently while arterial oxygenation was improved only with 10 mg nifedipine. Venous shunt was significantly increased with 20 mg nifedipine whereas spirometric parameters were unaffected. The percent DLCO change with 10 or 20 mg nifedipine was inversely correlated with baseline DLCO, but not with the severity of obstruction. Nifedipine did not have any effect in the control group, except for mild hypotension and a reflex increase in the heart rate. It is concluded that 10 mg nifedipine probably has an effect on the pulmonary circulation in moderate COPD patients with pulmonary hypertension.