A double-blind study of the peripheral vasoconstrictor effects of the beta-blocking drug penbutolol in patients with Raynaud's phenomenon.

A double-blind, placebo-controlled study was carried out in 10 hypertensive patients who were subject to frequent attacks of Raynaud's phenomenon and suffered from cold hands, to assess the peripheral vasoconstrictor effects of penbutolol. After a wash-out period of 2 weeks on placebo, patients received two 14-day treatment periods, in random order, with either 20 mg penbutolol twice daily or placebo separated by a second 2-week single-blind wash-out period on placebo. The results of digital blood flow measurements showed that penbutolol did not produce any additional vasoconstrictor effect on digital circulation. The significance of these findings is discussed.