Opsumit (Macitentan): Getting the Most From Your Medication

FDA Approval of Opsumit

This medicine, Opsumit (Macitentan), was approved in 2014 based on a very large long-term study of 742 patients.  250 were randomized to placebo (sugar pill), 250 were randomized to 3mg once daily of Opsumit, and 242 were randomized to 10mg once daily.  Patients were then followed and their rates of clinical deterioration were recorded.  Exercise capacity was assessed at six months.  Patients were allowed to be on background PAH therapy.  The majority of patients were enrolled from outside of the United States.

PAH PhysicianOpsumit Effectiveness

The 10mg Opsumit dose was most effective and it reduced the rate of clinical deterioration by almost 50%.  The most powerful effect was on reducing the need for hospitalization.  There was modest improvement in exercise capacity.  Beneficial effects were also seen on pulmonary vascular resistance and blood flow through the pulmonary arteries.

Side Effects of Opsumit

The most common side effects were nasal symptoms, headache and anemia.  For most patients, nasal congestion and headache are mild.  If nasal symptoms are more troubling, we encourage our patients to try nasal saline spray first.  If that is helpful, nasal antihistamines may prove useful.  Headache usually responds to acetaminophen (Tylenol).  We generally check for anemia before starting therapy with Opsumit and at three months.  Opsumit may be taken with or without food.  Most patients take it in the morning but this is not required.

Pregnancy & Opsumit

Opsumit is absolutely forbidden in women who are or may become pregnant.  All women of child bearing potential must be enrolled in a monitoring program that requires a pregnancy test prior to starting therapy and each month.  Effective birth control must be used.

Certain drugs can increase the blood levels of Opsumit so always check with your physician prior to starting any new medications.  Don’t stop Opsumit without checking with your physician.