Treprostinil: new drug. Pulmonary artery hypertension: just another (disappointing) prostacycline analogue.

(1) Standard treatment for pulmonary artery hypertension usually combines a calcium channel blocker with an anticoagulant, supplemental oxygen, a digitalin and a diuretic, with only limited efficacy. When added to this standard treatment, long-term continuous intravenous epoprostenol (prostacycline) infusion improves survival time and quality of life in patients with severe primary pulmonary artery hypertension, but at a cost of many adverse effects, some of which can be serious. Bosentan, an endothelin receptor antagonist, is an oral alternative. (2) Following the approval of inhaled iloprost, another prostacycline analogue, treprostinil, has been approved for use as a continuous subcutaneous infusion. (3) Its clinical evaluation is based on 2 randomised double-blind placebo-controlled trials with disappointing clinical results: the 6-minute walking distance increased by only 10 meters after 12 weeks of treatment. This modest degree of improvement in an intermediate outcome is unlikely to translate into a tangible improvement in quality of life. (4) The only available comparison with epoprostenol is a clinical pharmacology study in about 20 patients, with no tangible clinical benefit. (5) The adverse effect profile of treprostinil is the same as that of epoprostenol, and is mainly due to its vasodilatory properties (diarrhoea, ankle swelling). In addition, pain and other local reactions are very frequent at the point of infusion. (6) Treprostinil must be administered as a continuous subcutaneous infusion; this is not convenient, but it is easier to set up than central intravenous epoprostenol infusion.