By: Rebecca Gilene, PharmD Candidate c/o 2014, St. Louis College of Pharmacy – The FDA approved macitentan (Opsumit®) on October 18, 2013 for the treatment of pulmonary arterial hypertension.1 Pulmonary arterial hypertension, often referred to as PAH, is a disease characterized by high blood pressure in the arteries between the heart and lungs. An increase…