Mannitol

Mannitol is a clear, almost colorless and sterile solution of Mannitol. Each 100 ml of Mannitol contains Mannitol BP 20 g. Administered parenterally, Mannitol raises the osmotic pressure of the plasma, thus drawing water out of body tissues and produces an osmotic diuresis. Mannitol is principally used by IV infusion as an osmotic diuretic to preserve renal function in acute renal failure and to reduce raised intracranial and intraocular pressure. Mannitol is also used as an irrigating solution to prevent hemolysis and hemoglobin buildup during transurethral prostatic resection. It is useful in the management of acute drug poisoning where a route of elimination is through kidney. Besides these, it is also used in symptomatic relief of edema, reperfusion injury, termination of pregnancy, and bowel preparation.

The adult dose of Mannitol ranges from 50 to 100 gm by IV infusion. The rate of administration is usually adjusted to maintain a urine flow of at least 30 to 50 ml/hr. Total dosage, concentration and the rate of administration depends on fluid requirement, urinary output and the severity of the condition being treated

Renal insufficiency-

• Adults: 50 to 100 g of Mannitol administered at a rate adjusted to maintain a urine flow of at least 30 to 50 ml/hr.
• Children: 2 gm/kg or 60 gm/m² of body surface area administered over a period of 2 to 6 hrs.

Cerebral edema, elevated intracranial pressure, elevated intraocular pressure, Glaucoma-

• Adults: 1.5 to 2 gm/kg administered over a period of 30 to 60 minutes.
• Children: 1 to 2 gm/kg body wt. or 30 to 60 gm/m² of body surface area administered over a period of 30 to 60 mins.

Adjunctive therapy for removal of toxic substances-

• Adults: 50 to 200 g of Mannitol administered at a rate adjust to maintain a urine flow of at least 100 to 500 ml/hr.
• Children: 2 gm/kg or 60 gm/m² of body surface area

For termination of pregnancy 50 gm of Mannitol (250 ml of Mannitol) is instilled into the amniotic cavity which induces abortion in a high proportion of pregnancies.

Mannitol intravenous infusion is contraindicated in patients with pulmonary edema or congestive heart failure. It is also contraindicated during inadequate urine flow, dehydration or acidosis, intracranial bleeding and in patients with renal failure unless a test dose has produced a diuretic response.

The most common side effects associated with Mannitol intravenous infusion is fluid and electrolytes imbalance including circulatory overload and acidosis at high doses. Other side effects include nausea, vomiting, thirst, headache, dizziness, fever, tachycardia, chest pain, hyponatraemia, dehydration, blurred vision, urticaria, and hypertension or hypotension.

Safety of Mannitol intravenous infusion in pregnancy has not been established yet. No information is available on the excretion of mannitol in breast milk and should be administered after careful consideration of risk-benefit ratio.

Careful monitoring of rate of administration of Mannitol is necessary to avoid fluid and electrolyte imbalance and circulatory overloading. The infusion should be discontinued if the patient develops signs of progressive renal dysfunction, heart failure or pulmonary congestion. Mannitol should not be administered with whole blood. Infusion of fluid should be immediately discontinued if rigor arises from any reason during the process. Do not use if the solution is cloudy, contains particles or after expiry date.

Osmotic diuretics

Mannitol should be stored at a temperature of 20° to 30°. Exposure to lower temperatures may cause deposition of crystals, which should be dissolved by warming the bottle in hot water for about 30 minutes. Cool to body temperature before using. If all crystals can not be dissolved, the solution should not be used. The content of open containers should be used promptly. Unused contents should be discarded.