Clinical and rheological effects of nifedipine in Raynaud's phenomenon.

Thirty-four patients with Raynaud's phenomenon, 28 primary and six secondary, were entered into a double-blind placebo controlled, randomized cross-over trial of nifedipine treatment. Nifedipine was given as a 20 mg biphasic release formulation twice daily. Twenty-nine patients completed the study, during which the mean number of attacks was reduced by 25% during nifedipine treatment (P less than 0.001). Twenty patients scored nifedipine higher than placebo on a five point rating scale (P less than 0.001). Unwanted effects were experienced by 26 patients during active treatment, resulting in withdrawal from the study in five. Red cell deformability and fibrinogen concentrations were not altered by nifedipine.