Dexamethasone — Drug Monograph

Brand names: Decadron, Dexamethasone Intensol

Drug class: Supportive Care Agent

Mechanism of Action

Synthetic glucocorticoid with broad anti-inflammatory and immunosuppressive properties. Its antiemetic mechanism in CINV is not fully elucidated, but proposed mechanisms include: inhibition of prostaglandin synthesis in the CNS, reduction of serotonin release in the GI tract, and interference with CNS permeability changes induced by chemotherapy. Synergizes potently with 5-HT3 antagonists and NK1 antagonists — the CINV prophylaxis regimen for HEC requires dexamethasone as a required component.

FDA Indications

• Prevention of nausea and vomiting associated with chemotherapy (as a component of multi-drug antiemetic regimens)
• Anti-inflammatory and immunosuppressive therapy across a broad range of indications
• Cerebral edema associated with brain tumors, surgery, or injury
• Allergic states and hypersensitivity reactions
• Prevention of infusion reactions (as premedication for taxanes and other agents)

Common Side Effects

• Insomnia/sleep disturbance (very common; counsel patients at start of regimen)
• Elevated blood glucose / hyperglycemia
• Increased appetite
• Mood changes (euphoria, irritability)
• Perineal burning/tingling with rapid IV administration
• Fluid retention / edema

Clinical Pearl

Dexamethasone is the oldest and most essential antiemetic in oncology — no 5-HT3 or NK1 antagonist is as effective alone as the combination of either with dexamethasone. The most common clinical error is forgetting to reduce the dexamethasone dose when NK1 antagonists are used: aprepitant and netupitant inhibit CYP3A4 and approximately double dexamethasone exposure. Day 1 dose should typically be 12 mg (not 20 mg) and Days 2–4 should be 8 mg (not 8 mg BID). Perineal itching with rapid IV push…

Related Therapies & Mechanisms

• Aprepitant (Emend) — Supportive Care Agent
• Avatrombopag (Doptelet) — Supportive Care Agent
• Darbepoetin Alfa (Aranesp) — Supportive Care Agent
• Defibrotide (Defitelio) — Supportive Care Agent