Prednisolon: the pathway in the body
This page shows the biochemical pathway of the active substance Prednisolon: where it arrives in the body, where it acts and which steps are affected by that. Every statement has a source. The page describes general textbook knowledge and says nothing about any individual person.
In brief
Prednisolone is a synthetic glucocorticoid. It blocks nothing — it binds the same receiver as the body's own cortisol and switches it on. The receptor moves into the cell nucleus and helps govern the reading of many genes.
What this is about
Cortisol is a steroid hormone the body makes itself. Its path has three ends that come together here:
- Inside the cell, cortisol binds the glucocorticoid receptor. The receptor moves into the cell nucleus and helps govern the reading of many genes.
- Cortisol reports back on itself: in the hypothalamus it slows the release of CRH, and in the pituitary gland the release of ACTH. Without CRH and ACTH the adrenal cortex forms less cortisol.
- The same receptor also sits in the gut wall, where calcium is absorbed, and in every cell of bone.
Prednisolone binds that same receptor, so the same feedback applies: while prednisolone is present, less CRH and ACTH reach the adrenal cortex, and it forms less cortisol of its own — the label describes this as suppression of endogenous corticosteroids. In the gut wall, less TRPV6 and calbindin are described under prednisolone, the two proteins that bring calcium in from the gut; the label also states a greater output of calcium with the urine. The same receptor sits in the cells of bone. Nothing is blocked on this path: the receptor is switched on, not inhibited — which is why prednisolone acts everywhere it sits.
What this means in an individual case depends on many things and belongs in a conversation with a doctor or health practitioner.
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The pathway step by step
- Prednisone → Prednisolone 11β-HSD1 In the body prednisone is converted completely into prednisolone. Between the keto and the OH form the enzymes 11β-HSD1 and 11β-HSD2 switch back and forth; the same enzymes also interconvert cortisone and cortisol. Source 4, 11
- Prednisolone → In the blood In the blood part of the substance is bound to the carrier protein CBG and to albumin. CBG also carries the body's own cortisol; only the unbound part passes into the cells. Source 5
- In the blood → Broken down in the liver The liver converts prednisolone further. The breakdown products leave the body with the urine, there as sulfate and glucuronide compounds. Source 11
- At the receptor → In the cell nucleus · Hsp90 lets go With the substance bound, the receptor lets go of the helper proteins and moves into the cell nucleus. There it settles on certain stretches of DNA and also damps other gene switches such as NF-κB and AP-1. Source 1
- In the cell nucleus → Gene reading By this route the receptor acts on the reading of numerous genes — in the immune system, in intermediary metabolism, in the gut wall and in bone. Source 1, 7
- CRH → ACTH CRH receptor CRH reaches the pituitary gland through fine blood vessels. There it binds its receptor and triggers the release of the hormone ACTH into the blood. Source 2
- ACTH → The body's own cortisol MC2 receptor ACTH binds the receptor MC2R in the adrenal cortex. The cortex then converts cholesterol over several steps into cortisol and releases it into the blood. Source 2
- Calcium from food → TRPV6 in the gut wall TRPV6 · calcitriol The channel TRPV6 leads calcium into the gut cell. How much of it is made is governed by calcitriol — the active form of vitamin D — through the cell nucleus. Source 8
- TRPV6 in the gut wall → Calcium in the blood calbindin, PMCA1b Calbindin carries calcium through the cell, the pump PMCA1b hands it to the blood. In experiments in mice, TRPV6 and calbindin in the duodenum were present at lower levels under prednisolone; the label also states a greater output of calcium with the urine. Source 6, 8, 11
- Osteocytes → Osteoblasts · sclerostin, Wnt system Sclerostin damps the Wnt system, through which osteoblasts mature from precursor cells. It is described that glucocorticoids damp maturation, activity and survival of osteoblasts. Source 7
What this active substance affects
- Cortisol — Binds the same receptor; through the feedback, hypothalamus and pituitary form less CRH and ACTH Source 1, 2, 3
- Calcium — In the gut wall, less TRPV6 and calbindin are described under prednisolone — the proteins that let calcium in Source 6, 8
- Potassium — The label states a slight mineralocorticoid action: more sodium into the cells, less potassium inside them Source 11
- Sodium — The same mineralocorticoid action lets more sodium enter the cells, according to the label Source 11
What takes part in these steps
- Vitamin D — Calcitriol, the active form, governs the making of TRPV6 and calbindin in the gut wall Source 8
- Zinc — Building block of the two zinc fingers with which the glucocorticoid receptor binds the DNA Source 9, 1
What the prescribing information states
The prescribing information for this substance comes from an older labelling format. It lists the reported reactions by organ system and gives neither frequencies nor a comparator or placebo group. The table therefore only repeats what stands there under each heading.
How to read this table: it holds no figures, because the label gives none. Without a comparison group it cannot be said how often a reaction occurs, nor whether it would be rarer without the substance — the list only says what was reported, ordered by organ system.
| What the prescribing information lists there | |
|---|---|
| Fluid and salts | Sodium retention, fluid retention, heart failure in susceptible people, potassium loss, hypokalaemic alkalosis, raised pressure in the circulation |
| Muscle and bone | Muscle weakness, steroid myopathy, loss of muscle mass, osteoporosis, vertebral compression fractures, aseptic necrosis of femoral and humeral heads, fracture of a long bone already damaged |
| Stomach and gut | Peptic ulcer with possible perforation and haemorrhage, pancreatitis, abdominal distension, ulcerative oesophagitis |
| Skin | Impaired wound healing, thin fragile skin, petechiae and ecchymoses, facial erythema, increased sweating; skin tests may come out weaker |
| Nervous system | Convulsions, raised pressure inside the skull with papilloedema, usually after the course, vertigo, headache |
| Hormone system | Menstrual irregularities, Cushingoid appearance, slowed growth in children, reduced responsiveness of adrenal cortex and pituitary — particularly in times of strain, decreased carbohydrate tolerance, appearance of a latent diabetes mellitus, higher insulin need in people with diabetes |
| Eyes | Posterior subcapsular cataracts, raised intraocular pressure, glaucoma, exophthalmos |
| Metabolism | Negative nitrogen balance from protein breakdown |
Because this label keeps no separate sections for trial and post-approval reports, everything named above stands in a single section. The full wording is given there.
Sources
- Oakley RH, Cidlowski JA. The biology of the glucocorticoid receptor: new signaling mechanisms in health and disease. J Allergy Clin Immunol 2013 · PubMed 24084075
- Herman JP, McKlveen JM, Ghosal S et al. Regulation of the Hypothalamic-Pituitary-Adrenocortical Stress Response. Compr Physiol 2016 · PubMed 27065163
- Priya G, Laway BA, Ayyagari M et al. The Glucocorticoid Taper: A Primer for the Clinicians. Indian J Endocrinol Metab 2024 · PubMed 39371659
- Chapman K, Holmes M, Seckl J. 11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action. Physiol Rev 2013 · PubMed 23899562
- Meyer EJ, Nenke MA, Rankin W et al. Corticosteroid-Binding Globulin: A Review of Basic and Clinical Advances. Horm Metab Res 2016 · PubMed 27214312
- Huybers S, Naber TH, Bindels RJ, Hoenderop JG. Prednisolone-induced Ca2+ malabsorption is caused by diminished expression of the epithelial Ca2+ channel TRPV6. Am J Physiol Gastrointest Liver Physiol 2007 · PubMed 16901990
- La Corte R, Trotta F, Adami S. Glucocorticoid receptors and bone. Curr Pharm Des 2010 · PubMed 20977422
- Christakos S, Li S, De La Cruz J et al. Vitamin D and the intestine: Review and update. J Steroid Biochem Mol Biol 2020 · PubMed 31655181
- Siegel KR, Kassotis CD. Friend and Foe?: Metals as Facilitators and Disruptors of Steroid Nuclear Receptor Signaling. Toxicol Sci 2026 · PubMed 42608812
- US prescribing information (United States): Prednisolone Oral Solution USP, DailyMed, version of 4 Sept 2026, sections DESCRIPTION and CLINICAL PHARMACOLOGY · Prescribing information
- US prescribing information (United States): Prednisone Delayed-Release Tablets, DailyMed, version of 12 Aug 2026, sections 12.1 Mechanism of Action and 12.3 Pharmacokinetics (Metabolism) · Prescribing information
- US prescribing information (United States): Prednisolone Oral Solution USP, DailyMed, version of 4 Sept 2026, section ADVERSE REACTIONS · Prescribing information
As of 2026-09-25. Draft, written by Claude to schema v2; sources checked in PubMed; expert approval pending
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