Corticosteroid
Dexamethasone (Decadron)
Also called Decadron
Indications
- Vasogenic cerebral edema from brain tumors, metastases or abscess
- Suspected bacterial meningitis, first dose before or with antibiotics; benefit is in pneumococcal disease (off-label)
- COVID-19 needing oxygen or ventilation (RECOVERY 2021) (off-label)
- Airway edema: croup and post-extubation stridor (off-label)
- Postoperative nausea and vomiting prophylaxis at induction (off-label)
- Early moderate to severe ARDS (DEXA-ARDS 2020) (off-label)
Dosing
| Where | Dose |
|---|---|
| Other common pushes | Dexamethasone: 6–10 mg IV |
| Antiemetics | Dexamethasone: Corticosteroid. 4–8 mg IV at induction (PONV 2025); 12 mg with an NK₁ antagonist for chemo (ASCO); hyperglycemia, perineal burning on fast push |
| Corticosteroid equivalence | Dexamethasone: 0.75 mg (long-acting; no mineralocorticoid effect) |
On the quick cards
- Dexamethasone (Decadron)EMS Field Drugs: Respiratory and allergy: long-acting corticosteroid for croup and asthma
- AntiemeticsPush and Emergency Meds: Class, typical adult dose and the caution that matters
- Corticosteroid equivalenceEquivalents and Conversions: Glucocorticoid doses with the same anti-inflammatory effect
Mechanism of action
Dexamethasone is a fluorinated glucocorticoid that binds the glucocorticoid receptor far more avidly than cortisol and has no meaningful mineralocorticoid activity. The bound receptor switches on anti-inflammatory genes and represses NF-κB and AP-1 targets (cytokines, adhesion molecules, COX-2, VEGF); in tumor vessels this tightens the leaky blood-brain barrier, so it shrinks vasogenic but not cytotoxic edema. Gene effects outlast plasma levels, so one dose acts for 36–54 h.
Pharmacology
- CNS: peritumoral edema shrinks and symptoms often improve within days; no help for cytotoxic edema after stroke or trauma
- Renal: no sodium retention or potassium loss
- Metabolic: hyperglycemia, even after one PONV dose, more in diabetes
- Endocrine: 25–30 times the glucocorticoid potency of hydrocortisone (0.75 mg matches 20 mg) with no mineralocorticoid effect; long, strong ACTH suppression; cortisol immunoassays do not detect it
- Fetal: crosses the placenta in active form because placental 11β-HSD2 inactivates it poorly, hence its use for fetal lung maturity
Pharmacokinetics
| Onset | IV: plasma peak within 5 min as phosphatases free the drug; clinical effects build over hours |
|---|---|
| Duration | Biologic effect 36–54 h (SmPC; tables give 36–72 h), so once-daily dosing works |
| Half-life | Plasma 3.5–4.5 h (mean 4 h, Hemady label) |
| Distribution | Vd about 1 L/kg; crosses the blood-brain barrier and placenta |
| Protein binding | About 77%, mainly albumin; little CBG binding |
| Metabolism | Liver CYP3A4, mainly to 6β-hydroxydexamethasone; P-glycoprotein substrate |
| Elimination | Urine, mostly as metabolites; under 10% unchanged |
| Bioavailability | Oral about 80%, so oral and IV doses are interchangeable |
Chemistry
- 9α-fluoro-16α-methylprednisolone: the 9α-fluorine raises both glucocorticoid and mineralocorticoid potency, and the 16α-methyl group cancels the mineralocorticoid effect; betamethasone is its 16β epimer
- Neutral and lipophilic; the IV form is the water-soluble 21-phosphate ester, cleaved by phosphatases within minutes
- US vials (4 and 10 mg/mL) state strength as dexamethasone phosphate: 4 mg equals about 3.3 mg of dexamethasone base
- Some vials contain sodium sulfite and benzyl alcohol, others none; pH 7.0–8.5; protect from light
Adverse effects and cautions
In the one-pagers
- Ventilator Liberation and TracheostomyBefore the tube comes out: Methylprednisolone 40 mg once 4 h before (Cheng 2011) or 20 mg every 4 h from 12 h before (François 2007); dexamethasone 5 mg every 6 h × 4 (Lee 2007).
- Pediatric Assessment and EmergenciesCroup, epiglottitis, bronchiolitis: Care: Dexamethasone; neb epi if stridor at rest: Upright, calm; expert airway: Gentle suction, O₂, fluids
- ARDSFluids, steroids and the pharmacologic trials: Corticosteroids blunt the inflammatory and fibroproliferative response. DEXA-ARDS (Villar 2020; 277 patients, P/F ≤200 on PEEP ≥10 and FiO₂ ≥0.5 at 24 h) gave dexamethasone 20 mg daily for 5 days then 10 mg for 5 days: 4.8 more ventilator-free days and 60-day mortality 21% vs 36%, hyperglycemia 76% vs 70%, no excess infection. In COVID-19, RECOVERY (2
- EMT By-Complaint Quick PagesBites, altitude and infection: Altitude (NASEMSO, Merck): descent is the definitive treatment; even 500-1,000 ft helps (NASEMSO), Merck advises 500-1,000 m for severe AMS. Oxygen to 90% or more. HAPE is the deadliest form and may need positive pressure ventilation. ALS drugs (dexamethasone for HACE, nifedipine for HAPE) and portable hyperbaric bags only bridge to descent.
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Other corticosteroid drugs
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Sources
- FDA label: dexamethasone sodium phosphate injection, Hikma (2024)
- FDA label: Hemady (2026)
- UK SmPC: dexamethasone 3.3 mg/mL, AS Kalceks (2023)
- RECOVERY Collaborative Group (2021)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.