STERILE UREA

Clinical safety rating: safe

Animal studies have demonstrated safety

How it works

Urea is a hygroscopic agent that increases the osmolarity of blood plasma, drawing water from tissues into the blood and enhancing urine output. It also acts as a topical keratolytic agent by dissolving intracellular matrix in the stratum corneum, promoting desquamation and softening hyperkeratotic skin.

What the body does with it

Metabolism	Urea is partially metabolized in the gastrointestinal tract by urease-producing bacteria, releasing ammonia. In the body, it is not significantly metabolized and is primarily excreted unchanged by the kidneys.
Excretion	Urea is primarily excreted renally, with approximately 90% eliminated unchanged in urine via glomerular filtration; negligible biliary or fecal elimination.
Half-life	Terminal elimination half-life is approximately 7-8 hours in patients with normal renal function; prolonged in renal impairment.
Protein binding	Negligible (<1%); does not significantly bind to plasma proteins.
Volume of Distribution	Vd approximately 0.5-0.7 L/kg, approximating total body water; distributes freely throughout extracellular and intracellular fluid.
Bioavailability	Oral: no systemic bioavailability as oral urea is degraded in gut; topical: negligible systemic absorption (<4% through intact skin).
Onset of Action	Intravenous: diuretic effect begins within 30-60 minutes; topical: keratolytic effect within minutes to hours.
Duration of Action	Diuretic effect lasts 3-6 hours post-IV; topical keratolytic effect lasts several hours depending on formulation.

Classification & Brands

Dosing & administration

0.5-1.5 g/kg intravenously over 1-2 hours every 12-24 hours as needed for reduction of intracranial pressure. Oral: 40-60 g/day in divided doses as a diuretic.

Dosage form	INJECTABLE
Renal impairment	Contraindicated in severe renal impairment (GFR <10 mL/min). For GFR 10-29 mL/min: reduce dose by 50% and monitor. No adjustment for GFR ≥30 mL/min.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 25%. Child-Pugh C: contraindicated due to risk of hyperammonemia.
Pediatric use	Intravenous: 0.5-1.5 g/kg/dose every 12-24 hours, not to exceed 120 g/day. Oral: 1-1.5 g/kg/day in divided doses for diuresis.
Geriatric use	Start at lower end of dosing range (0.5 g/kg IV), monitor renal function and fluid balance. Avoid in patients with dehydration or poor renal reserve.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

No significant drug interactions For topical use only can cause mild irritation.

Breastfeeding	Urea is a normal constituent of milk; systemic levels after topical or intravenous use are low. No specific M/P ratio available. Use is considered compatible with breastfeeding; caution with high-dose intravenous therapy due to potential for maternal hypernatremia.
Teratogenic Risk	Urea is considered to have low teratogenic risk. No human data indicate increased risk of major congenital malformations; however, use in the first trimester should be limited to situations where benefit clearly outweighs risk. In the third trimester, intravenous administration may cause maternal hypernatremia and fetal fluid shifts, which could theoretically affect fetal electrolyte balance.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Common Effects	xerosis
Serious Effects

Absolute Contraindications

Hypersensitivity to urea; severe renal impairment (when used intravenously); active intracranial bleeding (when used for intracranial pressure reduction); dehydrated or severely electrolyte-imbalanced patients.

Clinical Precautions

Precautions

Risk of fluid overload or electrolyte imbalance with prolonged use; monitor serum electrolytes and fluid status. Avoid extravasation when administering intravenously. Use with caution in patients with hepatic or renal impairment. Topical use may cause local irritation or burning sensation.

Clinical Tips & Counseling

Drug interactions

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