What Are Corticosteroids
Corticosteroids are potent anti-inflammatory and immunosuppressive medications that work by suppressing inflammatory gene expression and modulating immune cell function, making them cornerstone therapies for autoimmune diseases, inflammatory disorders, severe allergic reactions, transplant rejection prevention, and certain hematologic malignancies 1.
Mechanism of Action
Corticosteroids exert their therapeutic effects through multiple pathways:
Gene transcription modulation: They bind to glucocorticoid receptors in the cytoplasm, which then migrate to the nucleus and interact with transcription factors like nuclear factor-κB and activator protein-1 2. This suppresses inflammatory gene expression by recruiting histone deacetylase-2 (HDAC2) to reverse histone acetylation 3.
Cellular effects: They affect the number, distribution, and function of all leukocyte types and endothelial cells 2. Specifically, they modulate lymphocyte recirculation, induce lymphocyte depletion (particularly CD4 cells), inhibit cytokine secretion, and can induce apoptosis in primed T cells 4.
Anti-inflammatory actions: They reduce airway hyperresponsiveness, inhibit inflammatory cell migration and activation, block late-phase allergic reactions, and promote vasoconstriction while decreasing chemotaxis 5.
Clinical Applications
Corticosteroids have been used since the late 1940s and remain essential for treating:
- Autoimmune and inflammatory disorders (rheumatoid arthritis, inflammatory bowel disease)
- Respiratory diseases (asthma, COPD, severe pneumonia, ARDS)
- Severe allergic reactions
- Transplant rejection (as induction, maintenance, and antirejection therapy) 2
- Hematologic malignancies
- Specific conditions like HIVAN (HIV-associated nephropathy) 6
- Sepsis and septic shock 7
Prevalence of Use
Approximately 1-3% of adult populations in developed countries use oral corticosteroids at any given time, with rates reaching up to 10% in elderly populations 1. Long-term prescriptions increased from 0.59% to 0.79% between 1989 and 2008 in the United Kingdom 1.
Important Clinical Considerations
Adverse Effects
Even relatively low doses (equivalent to prednisone 2.5-7.5 mg/day) are associated with increased risks of:
- Diabetes and hyperglycemia
- Osteoporosis and fractures
- Hypertension
- Cardiovascular disease and thrombotic events
- Severe infections
- Gastrointestinal complications
- Increased mortality 1
HPA Axis Suppression
Prolonged supraphysiologic glucocorticoid therapy leads to hypothalamic-pituitary-adrenal (HPA) axis suppression by inhibiting corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) production, ultimately causing adrenal cortex atrophy 1. The risk of glucocorticoid-induced adrenal insufficiency varies by route: 48.7% for oral use, 52.2% for intra-articular administration, and 4.2% for nasal administration 1.
Common Pitfall
Glucocorticoid withdrawal syndrome can occur when tapering, manifesting with symptoms similar to adrenal insufficiency even when HPA axis function is intact. Tapering should be more rapid within the supraphysiologic range, followed by slower tapering at physiologic doses 1.