Study of Cicletanine for Pulmonary Arterial Hypertension (PAH)

The primary objective of this study is to compare the change in exercise capacity following treatment with cicletanine HCl or placebo in subjects with PAH. The secondary objectives of this study are: 1. To compare the change in other clinical measures of PAH following treatment with cicletanine HCl or placebo in subjects with PAH 2. To compare the safety and tolerability of cicletanine HCl to placebo in subjects with PAH Additionally, the long-term safety, tolerability, and efficacy of cicletanine HCl treatment will be evaluated.