This study aims to look at how teriparatide spreads through the nose and into the blood stream when it is given as a liquid with a nasal delivery system called CriticalSorb™. CriticalSorb has been developed by Critical Pharmaceuticals to improve the absorption of drugs through the nose into the blood stream in the hope that it will replace injections. For part of the study a radioactive compound (routinely used in the nuclear medicine clinic for diagnosis) will be added to the formulation in order to investigate how the formulation spreads through nose after it is sprayed.