Urea

Intravenous
Reduction of raised intraocular pressure
Adult: 0.5-1.5 g/kg of a 30% solution in 5-10% glucose or 10% invert sugar infused at a rate not exceeding 4 ml/min. Max: 120 g or 1.5 g/kg daily.
Child: <2 yr: 100mg/kg.
Renal impairment: Use with caution. Severe: Contra-indicated.
Hepatic impairment: Use with caution. Severe: contra-indicated.
Incompatibility: Can cause haemolysis when mixed with whole blood.

Intravenous
Reduction of raised intracranial pressure
Adult: 0.5-1.5 g/kg of a 30% solution in 5-10% glucose or 10% invert sugar infused at a rate not exceeding 4 ml/min. Max: 120 g or 1.5 g/kg daily.
Child: <2 yr: 100mg/kg.
Renal impairment: Use with caution. Severe: Contra-indicated.
Hepatic impairment: Use with caution. Severe: contra-indicated.
Incompatibility: Can cause haemolysis when mixed with whole blood.

Topical/Cutaneous
Ichthyosis and hyperkeratotic skin disorders
Adult: Apply to affected area bid to tid.

Severely impaired renal function, marked dehydration, frank liver failure. Pulmonary congestion or pulmonary oedema, active intracranial bleeding, heart failure. Sickle cell disease with signs and symptoms of CNS involvement.

Mild to moderate renal or hepatic impairment. Inject into large veins and do not infuse into veins of lower limbs of elderly patients to reduce the risk of thrombosis and phlebitis. Be careful to prevent extravasation. Reduce risk of haemolysis by using glucose or invert sugar solutions as diluent and avoid rapid inj. Do not stop infusion abruptly. Maintain adequate hydration and keep patient horizontal to decrease side effects. Monitor renal function and watch for signs of fluid and electrolyte imbalance. Rebound increase in intracranial and intraocular pressure may occur after 12 hr. Topical applications may be irritant to sensitive skin.

Venous thrombosis or phlebitis at inj site; haemolysis; sloughing or necrosis due to extravasation; fluid and electrolyte imbalance; hypersensitivity reactions; pulmonary oedema. Headache, nausea, vomiting, syncope, disorientation, dizziness, agitation, mental confusion, nervousness, hypotension, tachycardia, cardiotoxicity, hyperthermia.

topical paste & nail lacquer

Increased excretion of lithium.

Urea is an osmotic diuretic similar to mannitol but more irritant. It induces diuresis by increasing osmotic pressure of the glomerular filtrate and increasing excretion of sodium, potassium and chloride ions. Its osmotic effect also draws water from cells e.g. brain, CSF and anterior chamber of the eye, thereby decreasing intracranial or intraocular pressure. Unlike mannitol, urea penetrates the eye and causes a rebound increase in intraocular pressure if the plasma concentration of the drug is less than that in the vitreous humour. Applied topically, urea promotes hydration of keratin and mild keratolysis in dry skin. It increases water uptake by the stratum corneum and has an antipruritic effect.
Absorption: Rapidly absorbed from the GI tract.
Distribution: Distributed in extracellular and intracellular fluids (e.g. lymph, bile, CSF and blood). It crosses the placenta and penetrates the eye.
Excretion: Urine (unchanged).

Diuretics / Keratolytics