Pharm 101: Corticosteroids

Classification
  • Short-medium acting: hydrocortisone, prednisolone
  • Intermediate-acting
  • Long-acting: dexamethasone
  • Mineralocorticoids: fludrocortisone

Pharmacodynamics
  • Act on intracellular glucocorticoid receptors
  • Anti-inflammatory and immunosuppressive effects:
    • Affects concentration, distribution and function of peripheral leukocytes
    • Suppression of inflammatory mediators (cytokines, chemokines)
    • Inhibit macrophages and APCs
    • Inhibit PLA2 –> decrease PG/LT/PAF
  • Catabolic and antianabolic effects

Pharmacokinetics
  • PO, IV, IM, topical administration
  • Cortisol (naturally-occurring):
    • Bound to corticosteroid-binding globulin (CBG)
    • Half-life 60-90 minutes
    • Mostly hepatic metabolism
    • 20% converted to cortisone by kidneys

Relative potency
Drug nameGlucocorticoid activityMineralocorticoid activity
Cortisol11
Aldosterone0.33000
Cortisone0.70.8
Prednisolone40.5
Dexamethasone250

Dexamethasone
  • PO, IV, IM, topical administration
  • Half-life 36-54 hours
  • Compared with hydrocortisone, 30 times more potent, longer acting, and no salt retaining activity
  • Clinical uses:
    • Croup: 0.15-0.60mg/kg PO, single dose
    • Anti-inflammatory effect
    • Anti-emetic
    • Diagnostic testing: dexamethasone suppression test

Hydrocortisone
  • Clinical uses:
    • Acute airways disease
    • Anaphylaxis
    • Thyrotoxicosis
    • Sepsis

Corticosteroids in asthma
  • Mechanism of action:
    • Anti-inflammatory, inhibit production of inflammatory cytokines
    • Contraction of engorged vessels in bronchial mucosa
    • Potentiate effects of beta-receptor agonists
  • Do not directly cause bronchodilation, but reduce bronchial hyperactivity and reduce frequency of exacerbations if taken regularly

Adverse effects of chronic use
  • Insomnia
  • Peptic ulcer disease
  • Acute psychosis
  • Cushings syndrome (> 2 weeks):
    • Metabolic effects (moon face, truncal fat, weight gain, hyperglycaemia)
    • Osteoporosis
    • Hypertension
    • Impaired wound healing
  • Adrenal suppression (> 2 weeks)

Further reading

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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