Dexamethasone

Class Glucocorticoid
Chemistry

Steroid

Routes of administration

Oral or IV

Absorption

70-100% oral bioavailability

Solubility

pKa=12.42; lipid soluble; available as water-soluble salts for IV injection

Distribution

VOD=0.65L/kg; 65% protein-bound (mainly to albumin)

Metabolism

Metabolised extensively in the liver

Elimination

Inactive metabolites are eliminated in the urine

Time course of action

Half-life 4-5 hours (though biological activity persist for 36-72 hours)

Target receptor

Glucocorticoid receptor, which is a cytoplasmic and nuclear receptor, that regulates gene transcription and protein synthesis (but some actions are also attributed to membrane-bound receptors and nongenomic pathways)

Mechanism of action

A combination of genomic effects and nongenomic effects, where some (medium and long term) activity is mediated by the regulation of protein synthesis, and some more immediate effects are mediated by the interference in cell membrane function, intracellular second messenger systems and membrane-bound glucocorticoid receptors

Clinical effects

- Immunosuppression (decreased granulocyte and lymphocyte activity)
- Reduced airway oedema, bronchodilation
- Sensitisation to catecholamines, increased cardiac output
- Neuropsychiatric effects (euphoria, mania, insomnia, psychosis)
- Metabolic effects (hyperglycaemia, hyperlipidemia, decreased insulin sensitivity)
- Fatty tissue redistribution, osteoporosis, proximal myopathy
- Hypernaremia, hypokalemia, water retention
- Adrenal suppression
- Increased risk of opportunistic infections (Aspergillus, Pneumocystis, Strongyloides)

Literature reference

Czock et al (2019)

CICM details of understanding Level 2
Mentioned around Deranged Physiology
Related SAQs