DESCRIPTION
Mechanism of Action
• Precise mechanism of action in preventing and/or treating
chemotherapy-induced nausea and vomiting is not known.
• Suppresses prostaglandin release from hypothalamus, which may
then inhibit the subsequent process of nausea and vomiting.
• Possesses anti-inflammatory and immunosuppressive effects with
minimal mineralocorticoid properties.
Absorption
Well absorbed by the GI tract, and oral bioavailability is on the order of
60%–70%. Peak plasma levels are observed in 1–2 hours after doses of
0.5–3.0 mg and are independent of the route of administration.
Distribution
Dexamethasone binds corticosteroid-binding globulin and corticosteroidbinding
albumin to significantly less extent than does hydrocortisone.
Metabolism
Metabolism occurs primarily in the liver, and about 20% of the drug is
conjugated via glucuronidation. The main route of elimination is through
renal excretion with biliary
Indications
Treatment of nausea and vomiting associated with cancer chemotherapy
in combination with other antiemetics, including serotonin (5-HT3) receptor
antagonists, metoclopramide, and lorazepam.
Dosage Range
1. The optimal dose of dexamethasone for the prevention and/or treatment
of cancer chemotherapy-induced nausea and vomiting has not
been established.
2. Oral: Recommended dose is 4 mg PO every 4–6 hours for four
doses, with first dose given 1–6 hours before chemotherapy.
3. Intravenous (IV): Recommended dose is 10–20 mg IV before chemotherapy
and then 10–20 mg IV every 4–6 hours.
Special Considerations
1. Contraindicated in patients with an underlying psychiatric disorder,
including psychosis and depression.
2. Efficacy of dexamethasone may be decreased when used in the presence
of drugs that induce the liver microsomal P450 system, including
phenytoin, phenobarbital, and carbamazepine. In this setting,
the dose of drug may need to be increased.
3. Use with caution in patients with liver impairment and/or hypothyroidism
as increased drug effects may be observed.
4. Patients should be cautioned about possible neuropsychiatric side
effects, including mood changes, euphoria, depression, insomnia,
and in extreme cases, psychosis.
Toxicity 1
Electrolyte abnormalities with hypokalemia and hyperglycemia.
Toxicity 2
Fluid retention, peripheral edema, hypertension, and rarely, exacerbation
of congestive heart failure (CHF).
Toxicity 3
Neuropsychiatric effects, including mood changes, euphoria, headache,
insomnia, depression, and psychosis.
Toxicity 4
Increased white blood count (WBC) secondary to demargination.
SPECIFICATION
Glucocorticoid steroid
Category
Antiemetic agent
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