Effect of the dual endothelin receptor antagonist bosentan on Raynaud’s phenomenon secondary to systemic sclerosis: a double-blind prospective, randomized, placebo-controlled pilot study

Objective. To investigate the efficacy of the endothelin receptor antagonist, bosentan, in patients with RP secondary to SSc without pre-existing digital ulcers. Methods. Single-centre, randomized, prospective, double-blinded comparison of bosentan and placebo. Patients received either 62.5 mg bosentan twice daily for 4 weeks, followed by 125 mg twice daily for 12 weeks or matching doses of placebo. Results. Of the 17 patients enrolled, 16 completed the study and 1 withdrew from the study due to the reversible development of peripheral oedema. Compared with placebo, bosentan did not improve the frequency, duration, pain or severity of RP attacks. However, in contrast to placebo, bosentan significantly improved the functional scores. With respect to baseline, the scleroderma HAQ disability index changes were in favour of bosentan at Weeks 12 (P = 0.03) and 20 (P = 0.01), and the United Kingdom functional score changes at Weeks 8 (P = 0.038) and 16 (P = 0.039). Conclusions. Bosentan is not effective in SSc-related RP without pre-existing digital ulcers, but it might benefit functional impairment in those patients. Trial Registration. European Union Drug Regulating Authorities Clinical Trials, https://eudract.emea.europa.eu, EudraCT-Nr 2004-002686-21.