prednisone
Meaning of prednisone: Longer courses are wound down in steps rather than stopped outright, because the body pauses its own cortisol production.
Definition of prednisone
Prednisone is a synthetic corticosteroid, a tablet that imitates cortisol, the hormone produced by the adrenal glands. It is a prodrug: inactive when swallowed, it is converted by the liver into prednisolone, which does the actual work. That work is to reduce inflammation and to hold back the immune system across a wide range of conditions.
How does it work inside a cell?
Once converted, the drug slips through the cell membrane and binds a receptor waiting inside. The pair travels into the nucleus and settles onto the DNA, where it turns down the genes that build inflammatory messengers and turns up genes with the opposite effect. Because the mechanism runs through gene activity rather than through a channel or a pump, the benefit builds over hours rather than minutes. It also explains the breadth of the effect: almost every immune cell type is dialed back at once, which is powerful and indiscriminate in equal measure. This is the same pathway used by cortisol from the adrenal gland, simply driven harder.
What is it used for?
| Setting | What the drug is doing |
|---|---|
| Asthma or airway flare | Reducing swelling in inflamed airways |
| Severe allergic response | Blunting a reaction that is still building |
| Autoimmune disease | Suppressing an attack on the body's own tissue |
| Transplant care | Preventing rejection of the grafted organ |
| Some cancer regimens | Acting on lymphoid cancer cells, or reducing swelling around a tumor |
Why is stopping it not straightforward?
The adrenal glands make cortisol only when instructed to by the pituitary, and that instruction is switched off when a corticosteroid arrives from outside. After a prolonged course the glands have effectively been idle, and they cannot resume full output immediately. Stopping suddenly therefore leaves the body without enough cortisol at a moment when it is needed, producing fatigue, nausea, aching and low blood pressure. Courses are wound down in steps for that reason, and short courses of a few days do not raise the same concern. Other effects, including raised blood sugar, thinning bone, fluid retention and disturbed sleep, also scale with how long treatment lasts rather than with the dose alone.
Used in a sentence
Prednisone was prescribed for a tapering course to control the inflammatory flare.
Good to know
Prednisone must be converted by the liver into prednisolone before it acts, and prolonged use suppresses the body's own cortisol production, which is why extended courses are reduced gradually rather than stopped at once.