Kinetics of response to iloprost evaluated by laser speckle contrast analysis in systemic sclerosis

Iloprost (ILO) is recommended for the treatment of systemic sclerosis (SSc) microangiopathy, but there is no common consensus on its optimal dosage. The aim of this study is to evaluate the kinetics of response to ILO administered in a daily outpatient scheme in SSc subjects using laser speckle contrast analysis (LASCA).

Adult SSc patients in stable therapy with ILO administered for 6 h for 2 consecutive days every 4 weeks were enrolled. Peripheral finger perfusion was assessed by LASCA. Each patient underwent five LASCA evaluations: before and after each day of ILO (D1pre, D1post, D2pre, and D2post) and after 4 weeks (D30).

Twenty-seven SSc patients (77.8% female, mean age 61.5 years) were enrolled. LASCA showed an increase in perfusion at the end of each ILO course, but on the second day (both D1pre vs D2pre and D2pre vs D2post) the increase was no longer significant in half of the fingers. Moreover, compared to D1post, at the beginning of the second ILO day most of the fingers had already shown a significant reduction in perfusion. After 1 month, there were no statistically significant differences between the perfusion values of D1pre and D30.

This LASCA study highlights the transience of the vasoactive effect of ILO, with a perfusion benefit that is completely lost after 1 month. The brevity of the perfusion effect of ILO and the use of LASCA are elements to consider in the design of future SSc trials to determine the optimal ILO dosage.