OPSUMIT

What it is

OPSUMIT is available as a film-coated tablet containing 10 mg of macitentan or as a dispersible tablet containing 2.5 mg of macitentan. OPSUMIT is a dual ETA and ETB endothelin receptor antagonist. Macitentan is an orally active, dual ETA and ETB receptor antagonist that prevents the binding of ET-1 to its receptors.

Approved indications

**Film-coated tablets:** — Idiopathic pulmonary arterial hypertension — Heritable pulmonary arterial hypertension — Pulmonary arterial hypertension associated with connective tissue disease — Pulmonary arterial hypertension associated with congenital heart disease with repaired shunts in patients with WHO Functional class II, III or IV symptoms OPSUMIT is indicated for use as monotherapy or in combination with approved PAH treatments (phosphodiesterase-5 inhibitors or inhaled prostanoids). **Dispersible tablets (paediatric):** — Idiopathic pulmonary arterial hypertension — Heritable pulmonary arterial hypertension — Pulmonary arterial hypertension associated with connective tissue disease — Pulmonary arterial hypertension associated with congenital heart disease with repaired shunts — Pulmonary arterial hypertension with co-incidental congenital heart disease in paediatric patients with WHO Functional class I, II, III or IV symptoms Dispersible tablets are indicated for use in paediatric patients aged 2 years to less than 18 years, as monotherapy or in combination.

Dosing overview

**Adults:** The recommended dose of OPSUMIT in adults is one 10 mg film-coated tablet taken orally once daily. OPSUMIT should be taken orally once a day with or without food. **Paediatric patients:** The recommended dose of OPSUMIT in paediatric patients aged 2 years to less than 18 years is based on body weight, taken once daily: patients weighing 10 kg to less than 20 kg receive 5 mg (2 × 2.5 mg dispersible tablets); patients weighing 20 kg to less than 40 kg receive 7.5 mg (3 × 2.5 mg dispersible tablets); patients weighing 40 kg or more receive 10 mg (4 × 2.5 mg dispersible tablets). No dose adjustment is required in patients over the age of 65 years.

Key safety warnings

**Hepatic function:** Hepatic enzyme elevations and in some cases serious hepatic events, potentially related to therapy have been observed with endothelin receptor antagonists. The incidence of aminotransferase elevations (ALT/AST) greater than 3 times the upper limit of normal was 3.4% on macitentan 10 mg and 4.5% on placebo in a double-blind study in patients with PAH. Liver enzyme tests should be obtained prior to initiation of macitentan and monthly monitoring of aminotransferases during treatment with macitentan is recommended. Patients should be monitored for signs of hepatic injury. **Haematological changes:** Decreases in haemoglobin concentration and haematocrit have occurred following administration of endothelin receptor antagonists and were observed in clinical studies with OPSUMIT. In placebo-controlled studies, macitentan-related decreases in haemoglobin concentration were not progressive, stabilised after the first 4–12 weeks of treatment and remained stable during chronic treatment. Initiation of OPSUMIT is not recommended in patients with clinically significant anaemia. It is recommended that haemoglobin concentrations be measured prior to initiation of treatment and tests repeated during treatment as clinically indicated. **Pregnancy:** OPSUMIT may cause birth defects and is contraindicated in pregnancy.

Contraindications

OPSUMIT is contraindicated in women who are or may become pregnant and in women of child-bearing potential who are not using reliable contraception. OPSUMIT is contraindicated in patients with hypersensitivity to the active substance or to any of the excipients. OPSUMIT is contraindicated in patients with severe hepatic impairment (with or without cirrhosis) and in patients with baseline values of hepatic aminotransferases (AST and/or ALT) greater than 3 times the upper limit of normal.

PBS listing

OPSUMIT 10 mg film-coated tablet is listed on the PBS with 4 items requiring authority approval. The ex-manufacturer price is A$2299.25.

Regulatory history

OPSUMIT macitentan 10 mg film-coated tablet was first registered on the ARTG on 5 February 2014. In November 2014, the PBAC recommended the listing of macitentan for pulmonary arterial hypertension on the basis of acceptable clinical effectiveness and cost-effectiveness compared to existing treatments. OPSUMIT macitentan 2.5 mg dispersible tablet was first listed on the ARTG on 14 August 2025.