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Glucocorticoids are a class of steroid hormones secreted by the zona fasciculata of the adrenal cortex, also known as cortisol. They are mainly regulated by the hypothalamic-pituitary-adrenal (HPA) axis, and their secretion and synthesis are influenced by adrenocorticotropic hormone (ACTH).
Glucocorticoids are a class of steroid hormones secreted by the zona fasciculata of the adrenal cortex, also known as cortisol. They are mainly regulated by the hypothalamic-pituitary-adrenal (HPA) axis, and their secretion and synthesis are influenced by adrenocorticotropic hormone (ACTH).
They play an important regulatory role in the body’s development, growth, metabolism, and immune function. They are the most important regulatory hormones in the body’s stress response and are the most widely used and effective anti-inflammatory and immunosuppressive agents in clinical practice.
The secretion of endogenous glucocorticoids follows a circadian rhythm, with the lowest levels at midnight and the highest levels in the early morning. Additionally, under stress, the secretion of endogenous glucocorticoids can surge to about 10 times the normal amount.
Classification Details
Glucocorticoid drugs are classified into short-acting, intermediate-acting, and long-acting hormones based on their biological effect duration. Short-acting hormones are synthesized and secreted by the adrenal glands, while intermediate- and long-acting hormones are artificially synthesized.
Glucocorticoids have various physiological effects including regulating the biosynthesis and metabolism of carbohydrates, fats, and proteins; suppressing immune responses; anti-inflammatory, anti-toxin, and anti-shock effects. Different classes have different emphasis on these physiological effects.
1. Short-acting Glucocorticoids
Include: cortisone, hydrocortisone.
Characteristics: natural hormones with weak anti-inflammatory potency, short duration of action, less harmful to the HPA axis, not suitable for treating chronic autoimmune diseases, mainly used as replacement therapy for adrenal cortical insufficiency.
In addition, among the three, mineralocorticoid activity is the strongest, capable of sodium retention and potassium excretion, and promotes diuresis by increasing glomerular filtration rate and antagonizing antidiuretic hormone. Excessive amounts can cause water and electrolyte metabolism disorders.
2. Intermediate-acting Glucocorticoids
Include: prednisone, prednisolone, methylprednisolone, triamcinolone;
They have anti-inflammatory effects and half-lives between the short- and long-acting types, with fewer side effects than long-acting ones. They are the most commonly used glucocorticoids clinically mainly for treating rheumatic diseases, autoimmune diseases, and immunotransplant therapies.
3. Long-acting Glucocorticoids
Include dexamethasone, betamethasone, and others.
Characteristics: strong anti-inflammatory effects, long duration of action, preferred for anti-allergy and blocking therapy. However, they significantly suppress the HPA axis; thus, they are unsuitable for long-term use and should only be used for temporary treatment.
4. Equivalent Dose Conversion
Cortisone 25 mg = Hydrocortisone 20 mg = Prednisone 5 mg = Prednisolone 5 mg = Methylprednisolone 4 mg = Triamcinolone 4 mg = Betamethasone 0.75 mg = Dexamethasone 0.75 mg
5. Comparison of Tissue Penetration Ability
Blood-brain barrier penetration ability in descending order: methylprednisolone, dexamethasone, hydrocortisone
Placental barrier penetration ability: dexamethasone, methylprednisolone, prednisone
Replacement Therapy
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Used as supplementary replacement therapy for acute and chronic adrenal cortical insufficiency, hypopituitarism, and post-subtotal adrenalectomy.
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Preferred hormones: short-acting glucocorticoids (cortisone, hydrocortisone) are preferred, with cortisone 25 mg equivalent to hydrocortisone 20 mg.
During use, an asymmetric dosing schedule should be followed to simulate the normal physiological secretion cycle as much as possible. For example, when hydrocortisone is administered at 0.3–0.5 mg/kg/day, 2/3 of the total dose should be given before 8 a.m., and 1/3 in the afternoon.