The present invention relates to an injectable pre-formulation comprising: a)at least one of a mono-, di-or tri-acyl lipid and/or a tocopherol； b)optionally at least one phospholipid； c)at least one biocompatible, organic solvent； and d)at least one prostacyclin analogue or a salt thereof； wherein the pre-formulation forms, or is capable of forming, at least one liquid crystalline phase structure upon contact with excess aqueous fluid. Such compositions may additionally comprise polar co-solvents. Methods of treatment, particularly for management of pulmonary artery hypertension (PAH), severe PAH, Raynaud's disease, ischemia and related conditions are provided, as well as corresponding uses of the compositions. Administration devices comprising the formulations and kits comprising the devices are also provided.
