urea

urea (u-re´ah)

1. the chief nitrogenous endproduct of protein metabolism, formed in the liver from amino acids and from ammonia compounds; found in urine, blood, and lymph.

2. a pharmaceutical preparation of urea used to lower intracranial or intraocular pressure, to induce abortion, and as a topical skin moisturizer.ure´al

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urea nitrogen  the urea concentration of serum or plasma, conventionally specified in terms of nitrogen content and called blood urea nitrogen (BUN); an important indicator of renal function.

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u·re·a (y-r)

n.

A water-soluble compound that is the major nitrogenous end product of protein metabolism and is the chief nitrogenous component of the urine in mammals and other organisms. Also called carbamide.

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Urea

A by-product of protein metabolism that is formed in the liver. Because urea contains ammonia, which is toxic to the body, it must be quickly filtered from the blood by the kidneys and excreted in the urine.

Mentioned in: Blood Urea Nitrogen Test, Escherichia Coli, Kidney Function Tests

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urea

[yoo͡r′ē·ə]

Etymology: Gk, ouron, urine

a normal metabolic waste product from protein metabolism, used as a systemic osmotic diuretic and topical emollient.

indications It is prescribed systemically to reduce cerebrospinal and intraocular fluid pressure and is used topically as a keratolytic agent.

contraindications Severely impaired kidney function, active intracranial bleeding, marked dehydration, or liver damage prohibits its systemic use.

adverse effects Among the more serious adverse effects are pain and necrosis at the site of injection, headache, GI disturbances, and dizziness. There are no known severe reactions to topical use.

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urea [u-re´ah]

1. the diamide of carbonic acid found in urine, blood, and lymph, the chief nitrogenous constituent of urine, and the chief nitrogenous end-product of protein metabolism; it is formed in the liver from amino acids and from ammonia compounds.

2. a pharmaceutical preparation of this compound, administered intravenously as an osmotic diuretic to lower intracranial or intraocular pressure, injected transabdominally into the amniotic sac to induce abortion of a second trimester pregnancy, and included in topical preparations to moisten and soften rough, dry skin.



The amount of urea in the urine increases with the quantity of protein in the diet because urea is an endogenous and exogenous waste product: endogenous because some of it is derived from breakdown of body protein as tissues undergo disintegration and repair, and exogenous because some of it is derived from the deamination of amino acids absorbed from the intestinal tract but not utilized by the body. In severe nephritis or other disorders leading to renal failure, the concentration of urea in the blood may be greatly increased, as revealed by measurement of the blood urea nitrogen (BUN).

urea concentration test a test of renal efficiency, based on the fact that urea is absorbed rapidly from the stomach into the blood and is excreted unaltered by the kidneys; 15g of urea is given with 100mL of fluid, and the urine collected after 2 hours is tested for urea concentration.

urea nitrogen the urea concentration of serum or plasma, conventionally specified in terms of nitrogen content and called blood urea nitrogen (BUN), an important indicator of renal function.

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urea (ūrē´),

n a water-soluble compound that is the primary constituent of urine.

Ureaplasma

n gram-negative eubacteria from the family Mycoplasmataceae that serve as a hydrolitic for urea. The bacteria do not have cell walls.

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urea

1. the diamide of carbonic acid found in urine, blood and lymph, the chief nitrogenous constituent of urine, and the chief nitrogenous end product of protein metabolism; it is formed in the liver from amino acids and from ammonia compounds.

2. a pharmaceutical preparation of urea occasionally used to lower intracranial pressure.

3. industrial urea is used as a fertilizer and feed additive for ruminants. Overfeeding or accidental access to large amounts can cause fatal poisoning.

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urea cycle

see urea cycle.

urea cycle enzyme deficiency

see arginosuccinate synthetase, citrullinemia.

urea hydrogen peroxide

see carbamide peroxide.

urea nitrogen

the urea concentration of serum or plasma, conventionally specified in terms of nitrogen content and called blood urea nitrogen (BUN), an important indicator of renal function.

urea poisoning

causes tremor, dyspnea, abdominal pain, incoordination, bellowing, convulsions and death in 2 to 4 hours. Due to hyperammonemia.

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hyperosmotic agent

A drug that makes blood plasma hypertonic thus drawing fluid out of the eye and leading to a reduction in intraocular pressure. It is used in solution in the treatment of angle-closure glaucoma and sometimes before surgery to decrease the intraocular pressure. Common agents include glycerin (glycerol), isosorbide, mannitol and urea. See hypertonic solution.

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urea

Pharmacologic class: Diamide salt of carbonic acid

Therapeutic class: Osmotic diuretic

Pregnancy risk category C

Action

Increases osmotic pressure of glomerular filtrate, inhibits tubular reabsorption of water and electrolytes, and elevates plasma osmolarity, increasing water influx into extracellular fluid

Availability

Powder for reconstitution: 40 g/150 ml

⊘Indications and dosages

➣ Increased intracranial pressure (ICP) or intraocular pressure (IOP)

Adults: 1 to 1.5 g/kg as 30% solution I.V., infused slowly over 1 to 2½ hours at a rate no faster than 4 ml/minute. Maximum dosage is 120 g/day.

Off-label uses

• Abortifacient

Contraindications

• Hypersensitivity to drug
• Severe renal impairment
• Marked dehydration
• Active intracranial bleeding
• Hepatic failure
• Infusion into lower leg veins in elderly patients

Precautions

Use cautiously in:
• hepatic or renal disease, electrolyte imbalances, diabetes mellitus, sickle cell disease, membrane rupture, cervical stenosis, uterine fibroids
• pregnant or breastfeeding patients.

Administration

• Add dextrose 5% or 10% in water to container with 40 g of urea, to yield a final concentration of 300 mg/ml. Infuse I.V. no faster than 4 ml/minute.
• Infuse through large-bore catheter into large vein only.
☞ Don't stop infusion abruptly.

Route	Onset	Peak	Duration
I.V.	30-45 min	1-2 hr	3-10 hr

Adverse reactions

CNS: headache, dizziness, agitation, confusion, disorientation, syncope, nervousness, drowsiness (with prolonged use in sickle cell patients), subdural hemorrhage

CV: hypotension, tachycardia, ECG changes, capillary bleeding, cardiotoxicity

GI: nausea, vomiting

GU: oliguria

Hematologic: hemolysis (with rapid administration)

Metabolic: hypervolemia, hyponatremia, hypokalemia, electrolyte imbalances

Skin: irritation or necrotic sloughing with extravasation

Other: pain, thrombosis, chemical phlebitis, or infection at injection site; fever; hyperthermia

Interactions

Drug-drug. Lithium: increased lithium clearance and decreased efficacy

Drug-diagnostic tests. Potassium, sodium: decreased levels

Patient monitoring

• Institute continuous cardiac monitoring.
• Closely monitor vital signs, ICP, and neurologic and cardiac status.
• Monitor electrolyte levels and kidney function tests.
• Assess fluid intake and output.
• When drug is used for IOP reduction, monitor IOP.

Patient teaching

• Explain drug therapy to patient.
☞ Tell patient drug may affect many body systems. Instruct him to immediately report such symptoms as headache or confusion.
• As appropriate, review all significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.