Liver impairment after concomitant administration of bosentan and clarithromycin in systemic sclerosis

Bosentan, an orally administered dual endothelin (A) and endothelin (B) receptor antagonist is indicated in the rheumatologic field for the treatment of pulmonary arterial hypertension related to connective tissue diseases [1] and for the prevention of the development of ischemic digital ulcers in systemic sclerosis [2]. As known, the drug may cause liver dysfunction; a recent report of a postmarketing surveillance quantified the increase of aminotransferase levels in 7.6% of the bosentan-treated patients [3]. Here we describe two cases of liver dysfunction after concomitant administration of bosentan and clarithromycin in systemic sclerosis.