Severe Hepatotoxicity in a Patient on Bosentan Upon Addition of Methotrexate Reversible With Resumption of Methotrexate Without Bosentan

Scleroderma is a multisystem disease in which the most common cause of death is pulmonary arterial hypertension (PAH), even in the absence of pulmonary fibrosis.' Targeted PAH therapies such as prostacyclins, endothelin receptor antagonists, and type 5 phosphodiesterase inhibitors provide clinical improvement and prolong survival. Consequently, there has been increased surveillance for and treatment of PAH. Patients with multiple medical comorbidities and polypharmacy are now being commenced on PAH therapies outside of trial settings, with potential for drug interactions and toxicity. We report a case of severe but reversible hepatotoxicity in a patient with stable liver function tests (LFTs) for 15 months on Bosentan therapy, 4 months after the introduction of methotrexate therapy.