Optimal use of treprostinil in pulmonary arterial hypertension: a guide to the correct use of different formulations.

Treprostinil is a synthetic prostacyclin analogue with antiplatelet and vasodilatory properties. It is the only prostacyclin analogue with different options of delivery, i.e. subcutaneous, intravenous, inhaled or oral. Subcutaneous treprostinil has been shown in short- and long-term studies to improve exercise capacity, functional class, haemodynamics and survival in patients with pulmonary arterial hypertension (PAH). Pain at the infusion site has been a major drawback of subcutaneous treprostinil, hampering dose titration, and ultimately leading to increased discontinuation rates. The additional clinical interest in treprostinil as an alternative intravenous prostacyclin has developed due to its favourable properties, including longer half-life, chemical stability, the possibility of intravenous infusion without the need for ice packs, and easy drug preparation. Intravenous treprostinil improves exercise capacity, functional class and haemodynamics in patients with PAH, over the period of 12 weeks. If patients are switched to intravenous treprostinil, they usually need to double the dose to attain the same efficacy. Whether the effect of intravenous treprostinil remains clinically relevant beyond 12 weeks is not known, and a longer follow-up would be required to investigate this. Inhaled treprostinil is an efficacious treatment in PAH patients who are moderately symptomatic on background oral therapy. Oral treprostinil on top of background therapy did not lead to an improvement in 6-minute walking distance after 16 weeks of treatment.