A research team has developed a long-acting injectable treprostinil depot that forms a drug-releasing gel inside the body, providing sustained pulmonary vasodilation for three to four days after a single intramuscular injection in rats with pulmonary arterial hypertension (PAH). The formulation prolonged drug residence, stabilized plasma concentrations, reduced pulmonary arterial pressure, and limited pulmonary vascular and right ventricular remodeling. It also showed favorable biocompatibility, with mild injection-site inflammation resolving within one week. If validated in further preclinical and clinical studies, this pump-free delivery strategy could reduce dosing frequency, simplify treprostinil administration, improve treatment adherence, and enhance quality of life for people living with PAH.