Pulmonary hypertension — UT-15
Patients suffering from pulmonary hypertension experience raised blood pressure in the blood vessels that supply the lungs. If it is too high, it injures the endothelial cells that line capillaries within the lung. The muscles contract excessively, restricting blood flow by narrowing blood vessels, resulting in an enlarged right ventricle. This causes chest pain, fainting and even heart failure. Primary pulmonary hypertension develops spontaneously, and the secondary form is complications, such as chronic lung problems or pulmonary embolism.
Treatments for normal hypertension do not work in primary pulmonary hypertension (PPH) and, until the development of the first pulmonary vasodilators, little could be done. The most potent vasodilator acting on the pulmonary circulation is prostacyclin. It is the main metabolite of arachidonic acid in the vascular system. Prostacyclin induces vasodilation, and therefore has potential as a treatment for a range of cardiovascular problems, including PPH.
However, it is not ideal and the search for more stable analogues has led to the discovery by United Therapeutics of UT-15, a benzindene analogue of natural prostacyclin that is stable at room temperature which can be administered subcutaneously.
Clinical trials have shown its long-term efficacy and safety in PPH patients. In one study, 14 patients were treated for an average of 13 months, and seven of the eight patients who did not pull out of the trial saw significant improvements in exercise endurance.1 In a second study, 10 patients were treated and, of the seven patients left at the end, all had decreased mean pulmonary artery pressure.2
Short-term use trials on 270 patients also showed improved exercise ability, reduced pressure in the pulmonary artery and general improvement in clinical signs and symptoms.3 No significant side effects were reported, the most common being headache and nausea. Pulmonary hypertension is difficult to treat, and UT-15 may well prove to be a significant advance.