Objective: This study investigates the pharmacokinetics of nebulized prednisolone in two different dosages. Study design: Single-center, open-label study Study population: Healthy participants aged 18-75 years. Intervention (if applicable): Healthy volunteers receive a lower dose of nebulized prednisolone (46.75 mg).After a wash-out period of at least one week, each volunteer receives a higher dose of nebulized prednisolone (93.5 mg). Main study parameters/endpoints: To establish the time from nebulizing to maximum prednisolone concentration in serum and the area under the curve of prednisolone. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Participants are exposed to a single supraphysiological dose of glucocorticoids on two separate occasions. The risk of SAE is very limited. There is a small risk of an AE during blood sampling. If it is demonstrated that therapeutic plasma concentrations of prednisolone can be reached by nebulizing prednisolone, we intend to use the pharmacokinetic data to design and perform a clinical study with a dry-powder micronized prednisone inhalation. This would represent a novel and promising alternative treatment for an adrenal crisis. Patients with adrenal insufficiency could then be offered a much more patient-friendly and reliable alternative for intramuscular hydrocortisone injection.