Indications: pulmonary arterial hypertension; systemic sclerosis with ongoing digital ulcer disease (to reduce number of new digital ulcers)

Cautions: not to be initiated if systemic systolic blood pressure is below 85 mmHg; monitor haemoglobin before and during treatment (monthly for first 4 months, then 3- monthly); avoid abrupt withdrawal; monitor liver function before treatment, at monthly intervals during treatment, and 2 weeks after dose increase (reduce dose or suspend treatment if liver enzymes raised significantly)—discontinue if symptoms of liver impairment.

Contra-indications: acute porphyria

Hepatic impairment: avoid in moderate and severe impairment.

Pregnancy: avoid (teratogenic in animal studies); effective contraception required during administration (hormonal contraception not considered effective); monthly pregnancy tests advised.

Breast feeding: manufacturer advises avoid—no information available

Side Effects: diarrhoea, gastro-oesophageal reflux, flushing, hypotension, palpitation, oedema, syncope, headache, anaemia; less commonly thrombocytopenia, neutropenia, leucopenia; rarely liver cirrhosis, liver failure (see cautions above)

Dose: Pulmonary arterial hypertension, initially 62.5 mg twice daily increased after 4 weeks to 125 mg twice daily; max. 250 mg twice daily.

Systemic sclerosis with ongoing digital ulcer disease, initially 62.5 mg twice daily increased after 4 weeks to 125 mg twice daily.