💊 Dexamethasone

Dexamethasone is a potent, long-acting synthetic glucocorticoid, a type of corticosteroid. It has minimal mineralocorticoid activity compared to hydrocortisone or prednisolone.

Dexamethasone binds to intracellular glucocorticoid receptors, leading to changes in gene expression. Its high potency and long duration of action result in strong anti-inflammatory, immunosuppressive, and anti-emetic effects, by inhibiting inflammatory mediator production and suppressing immune responses.

Dexamethasone is used in conditions requiring potent and prolonged corticosteroid action, such as cerebral oedema (especially due to tumours), spinal cord compression, severe allergic reactions, and certain haematological malignancies. It is also used as an antiemetic in chemotherapy and for respiratory distress syndrome prevention in premature infants.

Absolute contraindications include systemic fungal infections (unless treated) and hypersensitivity. Relative contraindications include active untreated infections, peptic ulcer disease, uncontrolled diabetes, and severe osteoporosis, where the benefits must significantly outweigh the risks.

Due to its potency, adverse effects can be significant. These include fluid retention, hypertension, hyperglycaemia, increased appetite, and mood disturbances (e.g., psychosis, insomnia). Long-term use can lead to severe adrenal suppression, osteoporosis, Cushingoid features, and increased susceptibility to infection. Gastric irritation is also a concern.

Regular monitoring of blood pressure, blood glucose, and electrolytes is crucial, especially during prolonged or high-dose therapy. Patients should be observed for signs of infection, gastrointestinal bleeding, and psychological changes. Bone mineral density may need monitoring with long-term use.

Always check for allergies to corticosteroids. Be aware of significant drug interactions, particularly with NSAIDs (increased GI bleed risk), antidiabetic drugs (reduced efficacy), and CYP3A4 inhibitors/inducers. Counsel patients on the importance of not stopping abruptly, potential severe side effects, and the need for a steroid card if on long-term therapy.

Dexamethasone is distinguished by its high potency and long duration of action, making it suitable for conditions like cerebral oedema. Remember its minimal mineralocorticoid activity. It's a key drug in oncology for managing symptoms and as part of chemotherapy regimens. Always consider the risk of adrenal suppression with prolonged use.

SBAs often focus on dexamethasone's specific indications, such as cerebral oedema or spinal cord compression, and its role in chemotherapy-induced nausea and vomiting. Questions may also test the understanding of its high potency and long half-life, and the implications for adrenal suppression and side effect profile compared to other corticosteroids.