DEXAMETHASONE SODIUM PHOSPHATE

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.

How it works

Dexamethasone sodium phosphate is a glucocorticoid that binds to the glucocorticoid receptor, leading to anti-inflammatory and immunosuppressive effects by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis, and modulating gene expression.

What the body does with it

Metabolism	Primarily hepatic via CYP3A4; also undergoes 5α-reductase and 5β-reductase metabolism.
Excretion	Renal excretion of unchanged drug and metabolites accounts for approximately 60-70% of elimination; biliary/fecal excretion accounts for 30-40%.
Half-life	Terminal elimination half-life is 3-4 hours in adults; however, the duration of action extends beyond the plasma half-life due to intracellular receptor-mediated effects.
Protein binding	Approximately 77-84% bound, primarily to albumin and corticosteroid-binding globulin.
Volume of Distribution	Apparent volume of distribution is 0.8-1.0 L/kg, indicating distribution into total body water and extensive tissue penetration.
Bioavailability	Oral bioavailability is approximately 80-90%; intramuscular bioavailability is virtually 100%.
Onset of Action	Intravenous: rapid (within minutes); intramuscular: 30-60 minutes; oral: 1-2 hours.
Duration of Action	Duration of action is 24-72 hours depending on dose and route; the biological half-life is longer than plasma half-life due to glucocorticoid receptor binding and downstream effects.

Classification & Brands

Dosing & administration

4-20 mg IV or IM every 4-6 hours; for cerebral edema: 10 mg IV followed by 4 mg IM/IV every 6 hours; for shock: 20 mg IV initially then 2-6 mg/kg IV bolus or 40 mg IV every 2-6 hours as needed.

Dosage form	INJECTABLE
Renal impairment	No specific dose adjustment for GFR; use caution in severe renal impairment (e.g., GFR <30 mL/min) due to potential fluid retention; monitor electrolytes.
Liver impairment	Child-Pugh A or B: no dose adjustment; Child-Pugh C: reduce dose by 50% or use with caution due to impaired metabolism.
Pediatric use	0.15-0.3 mg/kg/day IV/IM divided every 6-12 hours; for cerebral edema: loading dose 1-2 mg/kg IV then 1-1.5 mg/kg/day divided every 4-6 hours; maximum 16 mg/day.
Geriatric use	Start at lower end of adult dosing (e.g., 2-4 mg IV/IM every 6 hours); monitor for hyperglycemia, fluid retention, and osteoporosis; adjust based on renal function.

Use during pregnancy

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	Minimal excretion into breast milk (M/P ratio ~0.5). At maternal doses ≤20 mg/day, infant exposure <10% of maternal dose. Avoid high-dose, long-term therapy; monitor for infant growth and adrenal suppression.
Teratogenic Risk	First trimester: Increased risk of cleft palate (odds ratio 3.4). Second/third trimesters: Fetal adrenal suppression, intrauterine growth restriction, premature birth. Chronic therapy: Additive risk of maternal hypertension, gestational diabetes, preterm birth.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Common Effects	immunosuppression
Serious Effects

Absolute Contraindications

["Systemic fungal infections","Hypersensitivity to dexamethasone or any component","Concurrent live or attenuated virus vaccines (relative)","Pregnancy (relative, risk vs. benefit assessment needed)"]

Clinical Precautions

Precautions

["Increased risk of infection due to immunosuppression","Adrenal suppression with prolonged use","Osteoporosis with long-term use","Gastrointestinal perforation or ulceration","Corticosteroid-induced myopathy","Neuropsychiatric effects including mood swings and psychosis","Cushing's syndrome with prolonged therapy","Growth suppression in children","Ocular effects such as glaucoma and cataracts","Cardiovascular effects including hypertension and fluid retention"]

Clinical Tips & Counseling

Drug interactions

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DEXAMETHASONE SODIUM PHOSPHATE

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.

How it works

What the body does with it

Metabolism	Primarily hepatic via CYP3A4; also undergoes 5α-reductase and 5β-reductase metabolism.
Excretion	Renal excretion of unchanged drug and metabolites accounts for approximately 60-70% of elimination; biliary/fecal excretion accounts for 30-40%.
Half-life	Terminal elimination half-life is 3-4 hours in adults; however, the duration of action extends beyond the plasma half-life due to intracellular receptor-mediated effects.
Protein binding	Approximately 77-84% bound, primarily to albumin and corticosteroid-binding globulin.
Volume of Distribution	Apparent volume of distribution is 0.8-1.0 L/kg, indicating distribution into total body water and extensive tissue penetration.
Bioavailability	Oral bioavailability is approximately 80-90%; intramuscular bioavailability is virtually 100%.
Onset of Action	Intravenous: rapid (within minutes); intramuscular: 30-60 minutes; oral: 1-2 hours.
Duration of Action	Duration of action is 24-72 hours depending on dose and route; the biological half-life is longer than plasma half-life due to glucocorticoid receptor binding and downstream effects.

Classification & Brands

Dosing & administration

4-20 mg IV or IM every 4-6 hours; for cerebral edema: 10 mg IV followed by 4 mg IM/IV every 6 hours; for shock: 20 mg IV initially then 2-6 mg/kg IV bolus or 40 mg IV every 2-6 hours as needed.

Dosage form	INJECTABLE
Renal impairment	No specific dose adjustment for GFR; use caution in severe renal impairment (e.g., GFR <30 mL/min) due to potential fluid retention; monitor electrolytes.
Liver impairment	Child-Pugh A or B: no dose adjustment; Child-Pugh C: reduce dose by 50% or use with caution due to impaired metabolism.
Pediatric use	0.15-0.3 mg/kg/day IV/IM divided every 6-12 hours; for cerebral edema: loading dose 1-2 mg/kg IV then 1-1.5 mg/kg/day divided every 4-6 hours; maximum 16 mg/day.
Geriatric use	Start at lower end of adult dosing (e.g., 2-4 mg IV/IM every 6 hours); monitor for hyperglycemia, fluid retention, and osteoporosis; adjust based on renal function.

Use during pregnancy

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	Minimal excretion into breast milk (M/P ratio ~0.5). At maternal doses ≤20 mg/day, infant exposure <10% of maternal dose. Avoid high-dose, long-term therapy; monitor for infant growth and adrenal suppression.
Teratogenic Risk	First trimester: Increased risk of cleft palate (odds ratio 3.4). Second/third trimesters: Fetal adrenal suppression, intrauterine growth restriction, premature birth. Chronic therapy: Additive risk of maternal hypertension, gestational diabetes, preterm birth.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Common Effects	immunosuppression
Serious Effects