Up to one fifth of the adult population has Raynaud's syndrome. In response to cold or stress, the fingers of patients with Raynaud's syndrome undergo characteristic circulatory changes. The fingers typically become white, caused by vasoconstriction, then blue, caused by capillary stagnation and, finally, red, when reactive hyperemia ensues. Women are more commonly affected than men, and the condition may be familial or associated with connective tissue diseases such as scleroderma or systemic lupus erythematosus. Treatment is generally unsatisfactory, and some cases are associated with side-effects such as headache or a drop in blood pressure. Because one possible etiology of Raynaud's syndrome is a defect in nitric oxide synthesis in the extremities, Tucker and colleagues studied the efficacy of a topical nitric oxide generating cream.

The study demonstrated the effect of a gel formulated from sodium nitrate and ascorbic acid on 10 healthy volunteers and 20 patients who were otherwise healthy but with severe Raynaud's syndrome. All participants were normotensive, and all were screened for connective-tissue disease before the study. The patients with Raynaud's syndrome all met the Allen and Brown criteria, having had at least five attacks per day or 10 attacks per week during cold weather, with each attack lasting more than 30 minutes.

Under standardized conditions, the micro-vascular blood flow and microcirculatory volume of the forearm were measured by infrared photoplethysmography and laser Doppler fluxmetry. The active solution was then applied to one forearm of each participant, and a placebo solution was applied to the other forearm. Changes in blood flow to the forearm and finger pulps were assessed on both arms.

The placebo solution had no effect on the microcirculatory volume or flux in patients or control subjects. The active gel produced a large vasodilator response in microcirculatory volume and flux in the fingers and forearms of both groups. No adverse effects were noted or reported.

The authors conclude that topical gels could provide effective and convenient treatment for severe Raynaud's syndrome without systemic effects. The only disadvantages appear to be the messiness of the gel and stinging if applied to broken skin.