urea (carbamide)
Ureaphil

Available forms
Available by prescription only
Injectable: 40-g vial

Indications and dosages
 Reduction of intracranial or intraocular pressure. Adults: 1 to 1.5 g/kg as a 30% solution given by slow I.V. infusion over 1 to 2 1/2 hours. Maximum dose is 120 g daily.
Children age 2 and older: 0.5 to 1.5 g/kg by slow I.V. infusion.
Children younger than age 2: As little as 0.1 g/kg by slow I.V. infusion may be given. Maximum, 4 ml/minute.
 To prepare 135 ml of 30% solution, mix contents of a 40-g vial of urea with 105 ml of D₅W or D₁₀W with 10% invert sugar in water. Each milliliter of 30% solution provides 300 mg of urea.
 SIADH ◇. Adults: 80 g as a 30% solution I.V. over 6 hours.
 Diuresis ◇. Adults and children older than age 2: 500 mg to 1.5 g/kg as a 30% solution given by slow I.V. infusion over 30 minutes to 2 hours.
Children age 2 and younger: 100 mg to 1.5 g/kg as a 30% solution given by slow I.V. infusion over 30 minutes to 2 hours.

Pharmacodynamics
Diuretic action: Elevates plasma osmolality, enhancing the flow of water into extracellular fluid such as blood, and reducing intracranial and intraocular pressure. Diuresis is induced by elevating osmolarity at the renal glomerulus thereby decreasing the tubular reabsorption of water.

Pharmacokinetics
Absorption: Administered I.V.
Distribution: Distributed into intracellular and extracellular fluid, including lymph, bile, and CSF.
Metabolism: Hydrolyzed in GI tract by bacterial urease.
Excretion: Excreted by kidneys.

Contraindications and precautions
Contraindicated in patients with severely impaired renal function, marked dehydration, frank hepatic failure, active intracranial bleeding, or sickle-cell disease with CNS involvement. Use cautiously in pregnant women, breast-feeding women, and patients with cardiac disease or impaired renal or hepatic function.

Interactions
Drug-drug. Lithium: Enhances renal excretion of lithium; lowers serum lithium levels. Monitor lithium levels closely.

Adverse reactions
CNS: headache, syncope, disorientation.
GI: nausea, vomiting.
Metabolic: altered electrolyte balance.
Skin: irritation or necrotic sloughing with extravasation.

Effects on lab test results
• May decrease potassium and sodium levels.

Overdose and treatment
Signs and symptoms of overdose include unusually elevated BUN levels, polyuria, cellular dehydration, hypotension, and CV collapse.
 Stop infusion and institute supportive measures.

Special considerations
 ALERT Avoid rapid I.V. infusion, which may cause hemolysis or increased capillary bleeding. Extravasation may cause reactions ranging from mild irritation to necrosis.
• Use only freshly reconstituted urea for I.V. infusion; solution turns to ammonia when left standing. Use within minutes of reconstitution.
• Don’t administer through same infusion line as blood.
• Don’t infuse into leg veins; this may cause phlebitis or thrombosis, especially in elderly patients.
• Maintain adequate hydration.
• If satisfactory diuresis doesn’t occur in 6 to 12 hours, stop urea and reevaluate renal function.
• Urea has been used orally on an investigational basis for migraine prophylaxis, acute sickle-cell crisis prevention, and correction of SIADH.
• Monitor fluid and electrolyte balance.
• Monitor BUN levels frequently in patients with renal disease.
• Watch for signs and symptoms of hyponatremia or hypokalemia (muscle weakness, lethargy) as early indications of electrolyte depletion (before serum levels are reduced).
• Indwelling urinary catheter should be used in comatose patients to ensure bladder emptying. Use of an hourly urometer collection bag facilitates accurate measurement of urine output.
Breast-feeding patients
• It isn’t known if drug appears in breast milk. Safety in breast-feeding women hasn’t been established.
Geriatric patients
• Elderly or debilitated patients will need close observation and may need lower doses. Excessive diuresis promotes rapid dehydration and hypovolemia, hypokalemia, and hyponatremia.

Patient education
• Advise patient of need to monitor fluid balance, electrolyte balance, and BUN level.
• Advise patient to report muscle weakness and lethargy.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use