Parathyroid hormone (PTH) is used to treat hypoparathyroidism (HPT), a rare endocrine disorder caused by deficient or absent PTH hormone. PTH plays a critical role in controlling calcium, phosphate and vitamin D levels in the blood and bone. OPKO Biologics is developing a long acting PTH utilizing a stabilizer-based technology to extend its serum half-life and to reduce the frequency of injections, with the goal of reaching once weekly administration.