Ambrisentan: a guide to its use in pulmonary arterial hypertension classified as WHO functional class II or III.

The article presents an overview of the development of the drug ambrisentan and discusses the mechanisms by which it works. A discussion of patients for whom the drug may be suitable, and of the ways that it should be used in patients with pulmonary arterial hypertension that is classified as World Health Organization functional class two or three, is presented.