Disappearance of molsidomine effects on pulmonary circulation of patients with chronic obstructive pulmonary disease after a three week treatment.

The effect of oral molsidomine (M) on the pulmonary artery hypertension of patients with chronic obstructive pulmonary disease (COPD) was investigated during an acute study (4 mg once) and after a 3 week-treatment (3 times 4 mg a day), on a double-blind basis in 16 patients, 8 receiving a placebo, and 8 molsidomine. Ventilatory and cardiocirculatory indices were obtained at rest and during exercise. When acutely given, molsidomine reduces the mean pulmonary arterial pressure (PAP), the pulmonary vascular resistance (PVR) and the arterial O2 partial pressure (PaO2), increasing heart rate (HR) as well as the alveo-arterial O2 partial pressure difference (P(A-a)O2). During exercise, pulmonary arterial pressure and pulmonary vascular resistance decrease while heart rate increases without modification of arterial blood gases. After a 3-week treatment, molsidomine no more improves any index but significantly reduces cardiac output during exercise and consequently the O2 delivery to the tissues. The same feature has already been observed for other nitrates. It thus seems inappropriate to prescribe nitrates or nitrate-like drugs to chronic obstructive pulmonary disease patients with a view to lower their pulmonary hypertension.