Videophotometric capillaroscopy for evaluating drug effects on skin microcirculation--a double-blind study with nifedipine.

By videophotometric capillaroscopy, blood flow dynamics in the nutritional skin capillaries of man can be quantified. In this double-blind crossover study the acute effect of nifedipine on finger nailfold capillary blood cell velocity (CBV) was investigated in 10 healthy subjects. At the moment of administration of 10 mg nifedipine or placebo sublingually, a transitory but significant increase in heart rate and reduction of digital pulse amplitude (DAPA) were seen. Subsequent measurements of DAPA and heart rate were not significantly different from the baseline ones. CBV however increased after 10 min to a maximum of 49% above baseline values (P less than 0.05) after nifedipine but was unaffected by placebo. The reactive hyperaemia response in the capillaries were unaffected by both placebo and nifedipine. The decrease in DAPA and increase in heart rate upon administration of the drug or placebo are compatible with an increase in sympathetic activity. The subsequent increase in CBV indicates that nifedipine diminishes precapillary vascular tone. However, the drug seems to affect arterio-venous shunt flow to a lesser extent since DAPA did not increase significantly. Videophotometric capillaroscopy is a suitable method for studying the effects of pharmacological compounds on nutritional circulation in human skin.