Studies with oral and intravenous dosing of radiolabeled ciclesonide have shown an incomplete extent of oral absorption (%). The oral bioavailability of both ciclesonide and the active metabolite is negligible (<% for ciclesonide, <1% for the metabolite). Based on a γ-scintigraphy experiment, lung deposition in healthy subjects is 52%. In line with this figure, the systemic bioavailability for the active metabolite is >50% by using the ciclesonide metered dose inhaler. As the oral bioavailability for the active metabolite is <1%, the swallowed portion of the inhaled ciclesonide does not contribute to systemic absorption.