mannitol

Mannitol is a diuretic medication that promotes urination and is administered intravenously to reduce intracranial pressure and intraocular pressure from fluid buildup. Mannitol is used to treat acute kidney failure in the phase of reduced urine output (oliguric phase), to increase urination and improve kidney function before the kidney is irreversibly damaged. Mannitol is also used to flush out toxins from the kidneys and for evaluating kidney function.

Mannitol is a naturally occurring sugar alcohol found in many plants, seaweed, fruits and vegetables. Mannitol used as a medication is synthetically manufactured from fructose, or extracted from seaweed. Mannitol is also used as a sweetener for diabetic food products because very little of it is absorbed, hence it doesn’t increase blood glucose as much as some of the other sugars such as sucrose.

Mannitol is poorly reabsorbed in the kidneys and most of it is rapidly excreted. Mannitol hinders water reabsorption in the kidneys, increasing the excretion of sodium and chloride along with the water, as well as toxic substances. In addition to improving kidney function, mannitol also draws out the water content from cells into extracellular spaces and blood vessels which then gets excreted by the kidneys. This helps reduce pressure build up from fluid in intracranial and intraocular spaces.

The uses of mannitol include the following:

Therapeutic

• Reduction of intracranial pressure associated with cerebral edema or brain mass 
• Reduction of intraocular pressure if this is not achievable by other means
• To promote urination (diuresis) in acute renal failure and prevent or treat the oliguric phase before irreversible damage
• To promote the excretion of toxic substances, materials, and metabolites by increasing urine output
• Prevention of renal failure during cardiovascular and other types of surgery (off-label)

Diagnostic

• To evaluate kidney function by measuring the glomerular filtration rate (GFR), a test that checks how quickly the kidneys filter out mannitol

• Do not administer mannitol to patients with any of the following conditions:
  • Hypersensitivity to mannitol or any of its components
  • Complete absence of urination (anuria) due to severe kidney disease
  • Severe dehydration and low blood volume (hypovolemia)
  • Severe pulmonary vascular congestion or pulmonary edema
  • Active intracranial bleeding, except during craniotomy surgery
  • Progressive heart failure or pulmonary congestion after starting mannitol therapy
• Stop mannitol infusion at the first sign of any hypersensitivity symptom; serious hypersensitivity reactions, including anaphylaxis, hypotension and dyspnea resulting in cardiac arrest and death have been reported
• Do not administer electrolyte-free mannitol solution simultaneously with blood products because it can cause clumping of red blood cells (pseudoagglutination). If simultaneous blood transfusion is essential, at least 20 mEq of sodium chloride should be added to each liter of mannitol solution to avoid pseudoagglutination
• Mannitol infusion can lead to renal complications including irreversible kidney failure, particularly in patients with kidney disease and patients on medications that are toxic to the kidneys (nephrotoxic); avoid concurrent administration with nephrotoxic drugs or other diuretics and discontinue mannitol if urine output declines after starting the therapy
• Excessive loss of fluid from sustained diuresis may result in severe dehydration and serious fluid and electrolyte imbalances; monitor carefully
• Sustained urine output may mask dehydration and hypovolemia; monitor closely
• If urine output doesn’t increase with mannitol, the accumulation of mannitol and fluid in the vascular and extracellular spaces and dehydration of the intracellular spaces can result in:
  • Toxicity to the central nervous system (CNS)
  • Aggravation of congestive heart failure (CHF)
  • Severe increase in blood volume (hypervolemia)
• Mannitol injection may increase blood flow to the brain which may:
  • Increase the risk of postoperative bleeding in patients who have had brain surgery
  • Worsen intracranial pressure
• Avoid leakage from the vein (extravasation) during mannitol infusion; can result in damage to skin tissue and excessive pressure buildup in enclosed muscle spaces (compartment syndrome)
• Mannitol solution may form crystals at low temperature; ensure the solution is clear and without crystals

Common side effects of mannitol include:

• Pulmonary congestion
• Fluid and electrolyte imbalance
• Excess acidity of body fluids and tissue (metabolic acidosis)
• Electrolyte loss
• Dryness of mouth
• Thirst
• Dehydration
• Increased urination (marked diuresis)
• Urinary retention
• Reduced or absent urination (oliguria or anuria)
• Blood in urine (hematuria)
• Acute kidney injury
• Increase in blood urea nitrogen (BUN), creatinine and other waste products (azotemia)
• Swelling of extremities (peripheral edema)
• Congestive heart failure
• Headache
• Blurred vision
• Dizziness
• Convulsions
• Rebound increase in intracranial pressure
• Nausea
• Vomiting
• Nasal inflammation (rhinitis)
• Cough
• Sweating
• Swelling of extremities (peripheral edema)
• Rash
• Hives (urticaria)
• Itching (pruritus)
• Infusion site reactions including:
  • Infection
  • Blood clot and inflammation in the vein (thrombophlebitis)
  • Inflammation
  • Arm pain
  • Redness (erythema)
  • Skin tissue death (necrosis)
  • Compartment syndrome and edema (with extravasation)
• Chills
• Fever
• Generalized pain
• Muscle pain (myalgia)
• Weakness (asthenia)
• Feeling unwell (malaise)
• Hypersensitivity reactions including:
  • Severe allergic reaction (anaphylaxis)
  • Shortness of breath (dyspnea)
  • Cardiac arrest
• Angina-like chest pains
• Palpitations
• Low blood pressure (hypotension)
• High blood pressure (hypertension)
• Rapid heartbeat (tachycardia)

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug.

Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

Injectable Solution

• 5%
• 10%
• 15%
• 20%
• 25%

Adult:

• The usual adult dosage ranges from 50 to 200 g in a 24-hour period, but in most cases, an adequate response will be achieved at a dosage of approximately 100 g/24 hours
• The rate of administration is usually adjusted to maintain a urine flow of at least 30 to 50 mL/hr.
• The total dose should be adjusted according to the clinical response and adverse events

Reduction of intracranial pressure and brain mass

• 1.5-2 g/kg as a 15% to 25% intravenous (IV) solution infused over 30-60 minutes

Reduction of Intraocular Pressure

• 1.5-2 g/kg as a 20% IV solution infused over 30-60 minutes

Oliguria

Test dose

• 200 mg/kg as a 15% to 25% IV solution infused over 3-5 minutes
• If urine flow does not increase, a second dose may be given; but if there is inadequate response, the patient should be re-evaluated.

Prevention of acute renal failure during cardiovascular and other types of surgery

• 50 to 100 g of mannitol as a 5%, 10%, or 15% solution

Treatment of oliguria

• 300 to 400 mg/kg of body weight or up to 100 g of 15% to 20% solution
• Doses should not be repeated in patients with persistent oliguria

Adjunctive therapy for intoxications

• 5% to 25% solution for as long as indicated if urinary output remains high
• Discontinue If benefits are not observed after 200 g 

Pediatric:

Reduction of intracranial pressure and brain mass

• 1 to 2 g/kg body weight or 30 to 60 g/m2 body surface area over a period of 30 to 60 minutes
• In small or debilitated patients, a dose of 500 mg/kg may be sufficient

Reduction of Intraocular Pressure

• 1 to 2 g/kg body weight or 30 to 60 g/m2 body surface area over a period of 30 to 60 minutes
• In small or debilitated patients, a dose of 500 mg/kg may be sufficient

Oliguria

Test dose

• 200 mg/kg or 6 g/m2 body surface area as a 15% to 25% IV solution infused over 3-5 minutes
• If urine flow does not increase, a second dose may be given; but if there is inadequate response, the patient should be re-evaluated.

Prevention of acute renal failure during cardiovascular and other types of surgery

• 50 to 100 g of mannitol as a 5%, 10%, or 15% solution

Treatment of oliguria

• 0.25 to 2 g/kg body weight or 60 g/m body surface area as a 15% to 20% solution over a period of 2 to 6 hours
• Doses should not be repeated in patients with persistent oliguria

Adjunctive therapy for intoxications

• 2 g/kg of body weight of a 5% or 10% solution
• The concentration will depend upon the fluid requirement and urinary output of the patient
• Discontinue If benefits are not observed after 200 g 

Adult and pediatric:

Measurement of Glomerular Filtration Rate (GFR)

• 100 mL of a 20% solution (20 g) should be diluted with 180 mL of sodium chloride injection (normal saline) or,
• 200 mL of a 10% solution (20 g) should be diluted with 80 mL of sodium chloride injection (normal saline)
• The resulting 280 mL of 7.2% solution is infused at a rate of 20 mL per minute.

• Rapid infusion of large amounts of mannitol will draw out the cellular water content, which can result in dehydration of the cells and excess fluid collection in the extracellular space, leading to low sodium levels (hyponatremia), fluid in the lungs (pulmonary edema) and congestive heart failure.
• Repeated doses should not be given to patients with persistent oliguria and the dosage must be carefully monitored and adjusted to avoid overdose.

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

• Mannitol has no known severe interactions with other drugs.
• Serious interactions of mannitol include:
  • tobramycin
• Moderate interactions of mannitol include:
  • dichlorphenamide
  • lurasidone
  • nitroglycerin rectal
  • sodium sulfate/magnesium sulfate/potassium chloride
  • sodium sulfate/potassium sulfate/magnesium sulfate
  • tobramycin inhaled
  • voclosporin
• Mild interactions of mannitol include:
  • entecavir
  • magnesium chloride
  • magnesium citrate
  • magnesium hydroxide
  • magnesium oxide
  • magnesium sulfate

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.

• It is not known if mannitol injection can affect reproduction or cause fetal harm if administered during pregnancy; use only if benefits outweigh potential risks.
• It is not known whether mannitol is excreted in human milk; use with caution in nursing mothers because many drugs are excreted in human milk.