Contradicting themselves on the same site

[Mayadill]

You could expect a dose of prednisone to stay in your system for 16.5 to 22 hours.

The elimination half life of prednisone is around 3 to 4 hours. This is the time it takes for your body to reduce the plasma levels by half. It usually takes around 5.5 half lives for a drug to be completely eliminated from your system.

How long does prednisone stay in your system? (drugs.com)

Prednisone’s half-life is two to three hours; this means it will be fully eliminated from your body around 11 to 16.5 hours after you take it.

How long does it take for prednisone to work? (drugs.com)

[PMRpro Ambassador]

The ONSET of action is about 2 hours.. The DURATION of action is 12 - 36 hours depending on the person.

[PRL1957]

Hi, Mayadill,

The half-life of prednisolone 'in the system' is not the complete picture. It is calculated by measuring the concentration in blood. But corticosteroids also diffuse across cell membranes and bind to glucocorticoid receptors, so at least some of the physiological action will depend on how long the steroid remains bound, which could be longer than its presence in plasma.

[Mayadill in reply to PRL1957]

Hi to you! Thanks. I think I read somewhere large differences in how long it goes on working lead to some people suggesting alternate-day dosing