Zelos Therapeutics, Inc., a private biopharmaceutical company focused on developing novel therapies for patients suffering from osteoporosis, and Nektar Therapeutics (Nasdaq: NKTR) today announced the initiation of a Phase 1 clinical trial of an inhaled powder formulation of Zelos’ proprietary parathyroid hormone Ostabolin-C(TM) (cyclic PTH-(1-31)). Nektar and Zelos entered into a collaboration to develop an inhaleable powder form of Ostabolin-C in January 2005.