Prednisone

Class Glucocorticoid
Chemistry

Steroid

Routes of administration

Oral

Absorption

80% oral bioavailability

Solubility

pKa=12.59; poor water solubility; highly lipid soluble

Distribution

VOD=1.0 L/kg; <50% protein-bound

Metabolism

Metabolised in the liver into prednislone, which is the active form of the drug.

Elimination

Eliminated rapidly by being converted into prednisolone, which is then eliminated by hepatic metabolism. Also is a substrate for P-glycoprotein, which is an efflux pump into the lumen of the gut.

Time course of action

Converted rapidly (over minutes) into prednisolone; half life of prednisolone is closer to 2-3 hrs

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
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