A randomized double blind cross-over trial of nifedipine in the treatment of primary Raynaud's phenomenon.

During three winter months, 23 women participated in a double blind placebo controlled cross-over clinical trial of nifedipine in the treatment of Raynaud's phenomenon. Nifedipine and placebo were given in random order for two consecutive four-week periods. The dose of nifedipine was increased from 5 mg three times daily (tds) to 15 mg tds. During the final two weeks, the median number of attacks of Raynaud's phenomenon on nifedipine was 2.3 per week compared to 5.0 on placebo (P less than 0.01). Fifteen patients gave nifedipine a higher drug evaluation score than placebo (P less than 0.01). Side-effects were experienced by 14 patients (61%) on nifedipine and by two on placebo (P = 0.005). Finger systolic pressure after digit cooling did not differ significantly at the end of each treatment period. Nifedipine is effective in primary Raynaud's phenomenon in most patients but side effects are common.