Corticosteroids in Medicine
Corticosteroids are among the most potent anti-inflammatory and immunosuppressive drugs available. Their broad effects on nearly every organ system demand careful dosing, monitoring, and tapering.
Mechanism of Action
Corticosteroids bind intracellular glucocorticoid receptors, forming complexes that translocate to the nucleus and modulate gene transcription. They suppress multiple inflammatory pathways simultaneously:
- Transrepression -- Inhibit NF-kappaB and AP-1 transcription factors, reducing production of cytokines (IL-1, IL-6, TNF-alpha), chemokines, and adhesion molecules.
- Transactivation -- Upregulate anti-inflammatory proteins like lipocortin-1 (inhibits phospholipase A2, blocking arachidonic acid release).
- Immune cell effects -- Reduce circulating lymphocytes, eosinophils, and monocytes while increasing neutrophil counts (demargination).
Potency Comparison
| Agent | Anti-inflammatory Potency | Mineralocorticoid Effect | Half-Life |
|---|---|---|---|
| Hydrocortisone | 1 (reference) | High | 8-12 h |
| Prednisone | 4 | Moderate | 12-36 h |
| Methylprednisolone | 5 | Low | 12-36 h |
| Dexamethasone | 25-30 | Minimal | 36-72 h |
Prednisone is a prodrug converted to prednisolone in the liver. In severe liver disease, prednisolone may be preferred directly.
Clinical Uses
- Inflammatory diseases -- Rheumatoid arthritis, SLE, IBD, vasculitis (often as bridge therapy while slower-acting DMARDs take effect).
- Allergic reactions -- Anaphylaxis (adjunct to epinephrine), severe asthma exacerbations, allergic rhinitis (intranasal).
- Respiratory -- COPD exacerbations, COVID-19 hypoxia (dexamethasone reduced mortality in RECOVERY trial).
- Autoimmune -- Multiple sclerosis relapses (IV methylprednisolone), autoimmune hepatitis.
- Oncology -- Lymphoma protocols, cerebral edema from brain metastases, antiemesis.
- Adrenal insufficiency -- Physiologic replacement (hydrocortisone) for Addison's disease.
Long-Term Adverse Effects
Chronic systemic corticosteroids affect virtually every organ system:
- Metabolic -- Hyperglycemia (steroid diabetes), weight gain, dyslipidemia, Cushingoid features.
- Musculoskeletal -- Osteoporosis (start calcium, vitamin D, and consider bisphosphonate early), avascular necrosis, myopathy.
- Infectious -- Immunosuppression increases risk of opportunistic infections, reactivation of latent TB and hepatitis B.
- Psychiatric -- Insomnia, mood swings, psychosis (steroid psychosis), cognitive impairment.
- Ophthalmologic -- Posterior subcapsular cataracts, increased intraocular pressure.
- Dermatologic -- Skin thinning, easy bruising, poor wound healing.
- Adrenal suppression -- HPA axis suppression after >2-3 weeks of use; abrupt cessation causes adrenal crisis.
Tapering Principles
Gradual dose reduction is mandatory after prolonged use (>2-3 weeks) to allow HPA axis recovery. Typical approach: reduce by 10-20% every 1-2 weeks. Stress doses may be needed during illness or surgery for up to a year after discontinuation.
Key Takeaways
- Corticosteroids are powerful but carry cumulative toxicity -- use the lowest dose for the shortest duration.
- Always plan an exit strategy (taper schedule, steroid-sparing agent transition) when starting systemic steroids.
- Bone protection should begin at initiation if therapy is expected to exceed 3 months.
- Never stop chronic corticosteroids abruptly -- adrenal crisis can be fatal.