Dexamethasone

Glucocorticoids

ATC code: H02AB02 (Dexamethasone)

Mechanism of action

Binds intracellular glucocorticoid receptors, translocates to the nucleus, and suppresses transcription of pro-inflammatory genes. Potent anti-inflammatory activity – 25–30 times stronger than hydrocortisone. Virtually no mineralocorticoid activity. Long-acting – half-life 36–54 hours.

Indications

Cerebral edema

First line

First-line for peritumoral cerebral edema and perioperative management in neurosurgery. Loading dose 10 mg IV, then 4 mg every 6 hours. Reduces vascular permeability and vasogenic edema. Not effective for cytotoxic edema – for example, in ischemic stroke.

Chemotherapy-induced nausea and vomiting prophylaxis

Adjunct

Component of standard triple antiemetic regimen for chemotherapy. Per ASCO and NCCN guidelines, dexamethasone is given with a 5-HT3 receptor antagonist and an NK1 receptor antagonist. Doses 8–20 mg depending on the emetogenicity of the regimen.

COVID-19

First line

First-line in hospitalized COVID-19 patients requiring supplemental oxygen or mechanical ventilation. The RECOVERY trial (2020, over 6,000 patients) showed a one-third reduction in 28-day mortality in ventilated patients and a one-fifth reduction in those on oxygen. No benefit in patients not requiring oxygen. Dose: 6 mg/day for 10 days.

Practical notes

Timing and administration

Take in the morning – this mimics the physiological cortisol peak and minimizes hypothalamic-pituitary-adrenal axis suppression. For short courses (up to 3 days), tapering is not needed. For courses longer than 2 weeks, gradual dose reduction is mandatory to prevent adrenal insufficiency.

Monitoring

For any course beyond 1 week, monitor blood glucose – glucocorticoids cause insulin resistance. In diabetics, insulin or oral hypoglycemic doses may need adjustment. With prolonged use – bone densitometry, potassium, and blood pressure monitoring. Increased infection risk – masks inflammatory symptoms.

Safety

Contraindications

Systemic fungal infections (unless patient is on antifungal therapy)
Hypersensitivity to dexamethasone
Live vaccines at immunosuppressive doses

Serious adverse effects

Adrenal insufficiency with abrupt discontinuation after prolonged use
Osteoporosis and fractures with chronic use
Immunosuppression – increased risk of opportunistic infections
Steroid-induced diabetes
Proximal myopathy
Psychosis (rare, at high doses)
GI ulceration when combined with NSAIDs

Common adverse effects

Hyperglycemia
Increased appetite
Insomnia
Mood changes – irritability, euphoria
Dyspepsia

PregnancyFDA C

FDA category C. Crosses the placenta (unlike prednisolone, which is metabolized by the placenta). High doses in the first trimester are associated with a small increased risk of cleft palate. Used for strict indications – for example, fetal lung maturation in threatened preterm labor.