Prostacyclin compounds and compositions comprising the same are provided herein. Specifically, prostacyclin compounds comprising treprostinil covalently linked to a linear C5-C18 alkyl, branched C5-C18 alkyl, linear C2-C18 alkenyl, branched C3-C18 alkenyl, aryl, aryl-C1-C18 alkyl or an amino acid or a peptide (e.g., dipeptide, tripeptide, tetrapeptide) are described. The linkage, in one embodiment, is via a carbamate, amide or ester bond. Prostacyclin compounds provided herein can also include at least one hydrogen atom substituted with at least one deuterium atom. Methods for treating pulmonary hypertension (e.g., pulmonary arterial hypertension) and portopulmonary hypertension are also provided.