Background Bosentan is indicated in the treatment of pulmonary hypertension. Commonly reported adverse reactions are abnormal liver function (10.9%).

Purpose To evaluate the risk of hepatotoxicity associated with bosentan, comparing incidence rates with the literature.

Materials and methods Retrospective observational study, including all patients with pulmonary hypertension treated with bosentan between June 2003 and April 2013. Patients with previous liver disease were excluded as well as patients referred to other hospitals.

Data collected included age, sex, liver aminotransferases (AST and ALT) before and during treatment and time until liver function changed.

Normal levels in men were defined as AST 0–4 U/mL and ALT 0–40 U/mL. In women AST is 0–33 U/mL and ALT is 0–32 U/mL.

Results The study described 32 patients treated with bosentan, six of whom were excluded: liver damage had been observed previously in 3 patients and no data in the other 3.

The other 26 were 12 men and 14 women with a median age of 65.5 years (18–87 years).

Serum transaminase levels were elevated to the upper limit normal (ULN) in 10 patients (38.5%). Measures taken were: dose reduction in 1 patient (3.8%), stop treatment in 6 patients (23.0%) and no change in 3 patients (11.5%). In all of them those increases were reversible on the next liver function monitored.

Patients had a mean score, before starting treatment, of AST = 19.3 U/mL and ALT = 15.9 U/mL. Average values during treatment were AST = 34.2 U/mL and ALT = 33.4 U/mL. Mean highest levels in patients with hepatotoxicity were AST = 135.7 U/mL and ALT = 145.6 U/mL.

In 7, elevation of transaminases occurred during the first 26 weeks of treatment. The median time of the event was 19 weeks (4–416 weeks).

The incidence of abnormal increase in hepatic aminotransaminase levels was 38.5%.

Conclusions The study describes a greater incidence of hepatotoxicity associated with bosentan than described in the literature. Treatment of these cases should be adjusted.

Presence of bosentan and problems with increasing liver aminotransferases are relatively common and serum concentrations should be monitored during treatment.

No conflict of interest.