BETHESDA, MD 21 October 2013—FDA on October 18 approved the marketing of macitentan, or Opsumit, as a treatment to delay the progression of pulmonary arterial hypertension, a debilitating disease.
The agency said clinical studies of the drug found that it could postpone some consequences of the disease, such as a decline in patients' ability to exercise.
According to the FDA-approved labeling (PDF) for macitentan, the recommended dosage of the endothelin-receptor antagonist is 10 mg once daily.
The drug's pregnancy category is X, meaning the risk of macitentan use in pregnant women clearly outweighs any possible benefit. A boxed warning in the labeling tells clinicians to exclude the possibility of pregnancy in female patients before macitentan therapy begins, monthly during treatment, and one month after treatment stops. Clinicians must also tell female patients to use contraception while taking macitentan and for the first month after stopping therapy.
This boxed warning also states that the drug is available to female patients only through the Opsumit Risk Evaluation and Mitigation Strategy, which requires female patients to enroll in the restricted program and pharmacists and prescribers to be certified. There is an FDA-required Medication Guide.
The labeling also instructs clinicians to obtain liver-enzyme test results and hemoglobin level for patients before starting them on macitentan therapy and thereafter "as clinically indicated." Other endothelin-receptor antagonists, the labeling states, have caused elevations of transaminases, hepatotoxicity, liver failure, and decreases in hemoglobin concentration and hematocrit.
During the clinical studies of macitentan in patients with pulmonary arterial hypertension, the most common adverse events in participants who received 10 mg/day of the drug were nasopharyngitis, pharyngitis, headache, anemia, bronchitis, urinary tract infection, and influenza.
Actelion, which will market Opsumit, said it should become available to patients in November.
The product will be available as 10-mg tablets in 15-count blister packs and 30-count bottles. Both should be stored at 20–25 °C.