DEXAMETHASONE ACETATE
Clinical safety rating: avoid
CYP3A4 inducers (eg phenytoin) may decrease efficacy and inhibitors may increase effects Can cause hyperglycemia and adrenal suppression with prolonged use.
Agonist at glucocorticoid receptors, modulating gene expression to suppress inflammation, immune response, and adrenal function.
| Metabolism | Primarily hepatic via CYP3A4. |
| Excretion | Renal (primarily as glucuronide and sulfate conjugates) and biliary/fecal (minor). Approximately 65-80% of a dose is excreted in urine within 24 hours as 20-beta-dihydrodexamethasone (inactive) and conjugated metabolites; about 10-15% appears in feces. Less than 5% is excreted unchanged. |
| Half-life | Terminal elimination half-life: 3-5 hours in adults; slightly prolonged in neonates (approximately 12-24 hours) and patients with hepatic impairment. Clinical context: Duration of HPA axis suppression may exceed the presence of measurable drug; single dose typically suppresses cortisol for 24-36 hours. |
| Protein binding | Approximately 77-84% bound, primarily to albumin and to a lesser extent to alpha-1-acid glycoprotein. |
| Volume of Distribution | Approximately 0.6-0.8 L/kg (adults). This reflects moderate tissue distribution; drug crosses placenta and enters breast milk. |
| Bioavailability | Oral: approximately 80-90% (first-pass metabolism minimal). Intramuscular: 100% (by definition). Subcutaneous: 100% (by definition). Topical/ophthalmic: variable, but systemic absorption is minimal (<1% for most topical formulations, except when applied to large areas or broken skin). |
| Onset of Action | Intravenous: 1-2 hours (effects on glucose metabolism, inflammation). Intramuscular: 2-3 hours. Oral: 1-2 hours. Topical/ophthalmic: minutes to hours depending on formulation. Note: Onset of anti-inflammatory effect may be delayed up to 24-48 hours for some indications. |
| Duration of Action | Duration of biologic activity (glucocorticoid effect) is 36-54 hours; clinical duration for anti-inflammatory/immunosuppressive effects ranges from 24 to 72 hours depending on dose and individual. HPA axis suppression lasts 2-3 days after a single dose, longer with repeated dosing. |
0.5-9 mg/day orally in divided doses every 6-12 hours; intravenously or intramuscularly as dexamethasone sodium phosphate; typical anti-inflammatory dose 0.75-9 mg/day. For cerebral edema: IV loading dose 10 mg, then 4 mg every 6 hours. For COVID-19: 6 mg IV or orally once daily for up to 10 days.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment; not removed by hemodialysis. |
| Liver impairment | No specific Child-Pugh based guidelines; caution in severe hepatic impairment due to risk of fluid retention and increased glucocorticoid sensitivity. |
| Pediatric use | Anti-inflammatory: 0.08-0.3 mg/kg/day or 2.5-10 mg/m2/day orally in divided doses every 6-12 hours; cerebral edema: IV loading dose 0.5-1 mg/kg, then 0.1-0.5 mg/kg/day divided every 6 hours. |
| Geriatric use | Start at lower end of dosing range due to increased risk of osteoporosis, hyperglycemia, and fluid retention; monitor closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
CYP3A4 inducers (eg phenytoin) may decrease efficacy and inhibitors may increase effects Can cause hyperglycemia and adrenal suppression with prolonged use.
| FDA category | Positive |
| Breastfeeding | Enters breast milk. M/P ratio unknown. Based on prednisolone data, use lowest effective dose. Minimal risk at maternal doses ≤7.5 mg prednisolone equivalent. |
| Teratogenic Risk | Pregnancy Category C. First trimester: Increased risk of cleft palate (2-3 fold). Second/third trimester: Fetal adrenal suppression, growth restriction, and altered brain development. Avoid unless maternal benefit outweighs risk. |
■ FDA Black Box Warning
None.
| Common Effects | immunosuppression |
| Serious Effects |
["Hypersensitivity to dexamethasone or excipients","Systemic fungal infections","Administration of live or live-attenuated vaccines in immunosuppressed patients","Cerebral malaria","Idiopathic thrombocytopenic purpura (IM use)","Premature infants (IM use due to benzyl alcohol)"]
| Precautions | ["Hypothalamic-pituitary-adrenal (HPA) axis suppression","Increased susceptibility to infections","Masking of infection signs","Gastrointestinal perforation risk","Osteoporosis with long-term use","Cushing's syndrome","Adrenal crisis upon withdrawal","Growth suppression in children","Ocular effects (cataracts, glaucoma)","Ketoacidosis in diabetes","Increased intraocular pressure","Thrombotic events","Myopathy","Psychiatric disturbances","Vaccination risks with live vaccines","Kaposi sarcoma","Anaphylactic reactions"] |
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| Fetal Monitoring | Monitor fetal growth via ultrasound; assess for adrenal suppression in newborn (hypoglycemia, hypotension). Monitor maternal blood pressure, glucose levels, and signs of infection. |
| Fertility Effects | May inhibit ovulation and disrupt menstrual cycle due to hypothalamic-pituitary-adrenal axis suppression. Reversible upon dose reduction or discontinuation. |