Betamethasone

Class	Glucocorticoid
Chemistry	Steroid
Routes of administration	Topical
Absorption	65% oral bioavailability, but this is rat data
Solubility	pKa=12.42;poor water solubility; highly lipid soluble
Distribution	VOD=4-5L/kg; 65% protein-bound
Metabolism	Metabolised extensively in the liver into six inactive metabolites
Elimination	Inactive metabolites are eliminated in the urine
Time course of action	Half-life 11 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	Jobe et al (2020)
CICM details of understanding	Level 2
Mentioned around Deranged Physiology
Related SAQs

[Submit a comment or correction]