NPS-2143 is a novel potent and selective antagonist of Ca(2+) receptor with IC50 of 43 nM. Blockage of CaSR with NPS-2143 has being shown to prevent the development of pulmonary hypertension and right ventricular hypertrophy in animal models of pulmonary hypertension. The use of calcilytics, antagonists of CaSR, may be a novel therapeutic approach for PAH patients. Calcilytic drugs have been researched as potential treatments for osteoporosis, and as the first such compound developed, NPS-2143 is still widely used in research into the CaSR receptor as well as design of newer calcilytic agents. When administered together with an antiresorptive agent (estradiol), NPS 2143 causes an increase in trabecular bone volume and bone mineral density in osteopenic rats.