Molecular mechanism of action
Like other glucocorticoids, prednisolone acts intracellularly by interfering with genetic processes. Its action unfolds in several stages:
- Penetration through the cell membrane into the cell.
- Binding to specific intracellular (cytosolic) receptors.
- Translocation of the formed hormone-receptor complex into the cell nucleus.
- Interaction with gene promoters, leading to the regulation of DNA transcription.
The immunosuppressive effect is achieved by inhibiting the transcription of genes encoding major histocompatibility complex (MHC) proteins. The drug suppresses the synthesis of proinflammatory cytokines and inhibits T-lymphocyte proliferation. In addition, it causes marked suppression of lymphoid tissue proliferation.
Pharmacological effects and pharmacokinetics
Prednisolone belongs to medium-acting resorptive (systemic) action drugs. It has a high permeability across histohematic barriers, including the skin and mucous membranes.
Compared to natural hydrocortisone, prednisolone has:
- Glucocorticoid activity is more pronounced.
- Mineralocorticoid activity is less pronounced (it causes less sodium and water retention in the body).
The drug exerts a pronounced dose-dependent effect on metabolism. This effect is predominantly catabolic in nature. The main target tissues for prednisolone are lymphoid, adipose, and connective tissue, as well as muscles and skin.
Indications for use
Historically, glucocorticoids were the first drugs used to suppress immunity in organ transplantation. Today, prednisolone maintains its status as the reference immunosuppressant.
In oncohematology: Used in leukemias and lymphomas. The therapy dynamics are characterized by rapid remission, but relapse is eventually inevitable, and the drug's efficacy decreases after several courses.
- Included in treatment regimens for acute lymphoblastic leukemia (often combined with vincristine and the enzyme L-asparaginase).
- Used in polychemotherapy regimens (along with cyclophosphamide, doxorubicin, and vincristine) in combination with the targeted drug rituximab.
Adjuvant use in oncology: Prescribed to manage complications of the tumor process and side effects of chemotherapy, such as:
- Nausea and vomiting;
- Increased intracranial pressure;
- Hypercalcemia;
- Hemolysis.
In transplantology and immunology: Used to treat autoimmune diseases and prevent transplant rejection. It is also used as mandatory premedication (along with diphenhydramine and paracetamol) before the administration of muromonab-CD3 to prevent severe "cytokine release syndrome".
In pulmonology: Highly effective in bronchial asthma, but due to its systemic action, it is used with caution.
Side effects and safety profile
The main problem with prednisolone is the high risk of systemic side effects (unlike topical inhaled drugs such as beclomethasone or budesonide, which have high presystemic elimination).
Due to its pronounced catabolic effect, long-term administration of prednisolone leads to skin and muscle atrophy, and also negatively affects bone tissue, causing osteoporosis.
Note: When long-term therapy is required, methylprednisolone is often the drug of choice because it selectively accumulates in inflamed tissues and has a better safety profile (lower risk of tissue atrophy and osteoporosis).
Dosage forms and dosing
According to the prescription reference, prednisolone is available in the following forms:
- Tablets of 0.001 g and 0.005 g.
- Solution in ampoules of 2.5% and 3% (1 ml).
Dosing regimen:
- Replacement therapy: 0.02–0.03 g/day.
- Maintenance dose: 0.005–0.01 g/day.
- For intramuscular (i.m.) administration: 1 ml of 2.5% or 3% solution must be pre-diluted in 5 ml of water for injection.
Briefly: answers to topical questions
How does prednisolone affect carbohydrate metabolism?
The effect of prednisolone on carbohydrate metabolism consists in reducing glucose uptake by peripheral tissues, stimulating gluconeogenesis, and increasing blood glucose levels, leading to hyperglycemia. With long-term use, this can trigger steroid-induced diabetes mellitus. Decreased glucose tolerance or manifestation of latent diabetes mellitus is also possible.
Prednisolone is the FOREFATHER of all immunosuppressants (the first drug used to suppress immunity in transplantation).
Class and exam questions
What is the difference between prednisolone and hydrocortisone?
Prednisolone has more pronounced glucocorticoid activity and weaker mineralocorticoid activity. This means it causes less sodium and water retention in the body.
Why is methylprednisolone often preferred during long-term therapy?
Methylprednisolone selectively accumulates in inflamed tissues and has a better safety profile. Compared to prednisolone, it less frequently causes skin and muscle atrophy, and osteoporosis.
How does prednisolone affect metabolism?
It exerts a dose-dependent systemic effect with a predominantly catabolic orientation. Target tissues include lymphoid, adipose, connective tissue, muscles, and skin.
Why is prednisolone prescribed before the administration of muromonab-CD3?
It is used as mandatory premedication (along with diphenhydramine and paracetamol). This is necessary to prevent the "cytokine storm" that can occur upon the first administration of monoclonal antibodies.
What else to study on this topic
- Molecular mechanisms of gene transcription under the action of glucocorticoids
- Comparative pharmacokinetics of systemic and topical (inhaled) steroids
- Polychemotherapy regimens for lymphomas and the role of prednisolone in combination with rituximab
- Pathogenesis of "cytokine storm" and pharmacological rationale for premedication
- Mechanisms of the catabolic action of steroids on muscle and bone tissue
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