A controlled trial ofthe effect of topical glyceryl trinitrate on skin blood flow and skin elasticity in scleroderma

It has been suggested that in systemic sclerosis (SSc) the primary fault is in the microcirculation.' If this were so, then topical glyceryl trinitrate (GTN) might favourably influence skin blood flow and elasticity in areas of sclerodermatous skin change. Ten patients (three men, seven women; median age 48 years, range 24-70) fulfilling the American Rheumatism Association criteria for SSc2 were recruited into a doubleblind placebo-controlled clinical trial. All had forearm skin involvement and the median disease duration was 2-5 years, range seven months to 18 years. The extent of forearm skin involvement varied between patients. Most had mild skin thickening (involved, but skin could be pinched) and only one had classical 'hidebound' skin. For four weeks each patient applied topical GTN (2%) three times daily to a designated area of one forearm, and a lanolin-based placebo ointment to the corresponding area of the other. Careful instructions and a demonstration of how much ointment to apply were given and the patient wore gloves to minimise absorption from other sites. Elasticity (using a Cutech Extensometer), skin blood flow (by the laser Doppler technique using a Perimed PF3 instrument) and skin temperature (using a Heimann KT4 1 Bolometer) were measured at both sites at base-line, one hour post initial ointment application, and after two and then four weeks of treatment. The third and fourth assessments (at two and four weeks respectively) were made three hours after ointment application. Coefficients of variance (median and range) are 7-61) (1-7-22) for elasticity measurements, 42% (6-56) for laser Doppler readings and 2')/, (0 6-4) for bolometry. Baseline and post-treatment results within each group (GTN and placebo treated) were compared using a Signed rank test. Changes from baseline were compared between