Sildenafil is effective for Raynaud’s phenomenon resistant to vasodilatory therapy, according to the results of a randomized trial reported in the Nov. 8 issue of Circulation.
“Vasodilatory therapy of Raynaud’s phenomenon represents a difficult clinical problem because treatment often remains inefficient and may be not tolerated because of side effects,” write Roland Fries, MD, from the Universitätsklinikum des Saarlandes in Homburg/Saar, Germany, and colleagues. “Sildenafil is a selective inhibitor of cGMP [cyclic guanosine monophosphate]-specific phosphodiesterase type 5 (PDE-5). Besides its established effect in erectile dysfunction, sildenafil provides cGMP-dependent microvascular and macrovascular dilation.”
In this double-blind crossover study, 16 patients with symptomatic secondary Raynaud’s phenomenon resistant to vasodilatory therapy were treated with 50 mg of sildenafil or placebo twice daily for four weeks. The investigators used diary cards, including a 10-point Raynaud’s Condition Score to evaluate symptoms and laser Doppler anemometer testing, to measure capillary flow velocity in digital nailfold capillaries.
While patients took sildenafil, the mean frequency of Raynaud’s attacks was lower (35 ± 14 vs 52 ± 18; P = .0064), the cumulative attack duration was shorter (581 ± 133 vs 1,046 ± 245 minutes; P = .0038), and the mean Raynaud’s Condition Score was lower (2.2 ± 0.4 vs 3.0 ± 0.5; P = .0386) than when they took placebo.
After treatment with sildenafil, capillary blood flow velocity increased in each individual patient, and the mean capillary flow velocity of all patients more than quadrupled (0.53 ± 0.09 vs 0.13 ± 0.02 mm/second; P = .0004). Two patients discontinued the study drug because of adverse effects.
Study limitations include insufficient blinding and low overall frequency of symptoms.
“Sildenafil is an effective and well-tolerated treatment in patients with Raynaud’s phenomenon,” the authors write. “PDE-5 inhibition appears to be a promising new approach in patients with microcirculatory disorders.”
Two of the authors have disclosed financial arrangements with Pfizer, the maker of sildenafil; Boehringer Ingelheim; and Aventis.