ACEM Primary
Pharmacology of steroid medications
- Natural adrenocortical hormones are steroid molecules produced and released by adrenal cortex under the influence of ACTH from anterior pituitary
- Natural and synthetic forms are used in diagnosis and treatment of disorders of adrenal function, inflammatory and immunologic disorders
| Glucocorticoids | Mineralocorticoids | |
| Endogenous hormone | Cortisol 10-20mg secreted daily according to circadian rhythm T ½ 60-90 min Metabolised in liver and kidney 1% excreted unchanged as free cortisol in urine | Aldosterone Secreted from zona glomerulosa, average 100-200 mcg/day T ½ 15-20 mins Metabolised by liver and kidney Secreted in response to low Na+/ hypovolaemia (RAAS) and elevated K+ |
| Actions | Binds to glucocorticoid R which interact with target genes: Physiological – permissive effect on vascular smooth muscle response to catecholamines Metabolic – stimulate gluconeogenesis, glycogen synthesis (increase BGL) Protein catabolism and release of amino acids Stimulate lipolysis Anti-inflammatory effects – suppress cytokines/ chemokines, inhibit APC and macrophages, affect distributions of leukocytes CNS development | Bind mineralocorticoid receptor in cytoplasm: Renal – Promote reabsorption of sodium from DCT of kidney (via Na/K+ ATPase and ENAC) coupled with increased excretion of potassium and hydrogen ions Excess levels can lead to hypokalaemia, metabolic alkalosis and increase plasma volume. |
| Synthetic hormones | Have different ratios of glucocorticoid to mineralocorticoid activity which dictates their primary actions. Classification: Short- medium acting – hydrocortisone, prednisolone Long acting – dexamethasone Commonly used: Dexamethasone: PO/IV/IM/ topical, 30 times more potent than hydrocortisone, nil mineralocorticoid activity. Used for croup (0.15-0.6mg/kg PO), anti-emetic, anti-inflammatory. | |
| Toxicity | Short term- Insomnia, behavioural changes, peptic ulcers, pancreatitis (rare) Long term (>2 weeks) – Cushing’s syndrome: Moon facies, buffalo hump and central adiposity Acne, lanugo (fine hair growth)Muscle wasting Thinning of skin and hair Bruising, abdominal striae Osteoporosis, diabetes Poor wound healing, immunosuppression Hypomania, acute psychosis Sodium/ fluid retention and loss of potassium Adrenal suppression: When administered for >2 weeks, adrenal suppression may occur -> patient will require stress dosage in cases of trauma/ surgery and tapering of steroid doses |
Last Updated on August 12, 2021 by Andrew Crofton
Andrew Crofton
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