What are the health effects and usage guidelines for mannitol?

From the Guidelines

Mannitol should be used at a dose of 250 mOsm, infused over 15-20 minutes, to treat threatened intracranial hypertension or signs of brain herniation after controlling secondary brain insults, as recommended by the most recent and highest quality study 1.

Key Points

• The typical dosage for adults ranges from 0.25-2 g/kg administered intravenously, with specific dosing dependent on the condition being treated.
• For intracranial pressure reduction, a common regimen is 0.5-1 g/kg given over 20-30 minutes, while for kidney protection, lower doses of 0.25-0.5 g/kg may be used.
• Mannitol works by drawing fluid from tissues into the bloodstream through osmosis, increasing urine output and reducing fluid accumulation in the brain or eyes.
• Side effects include electrolyte imbalances (particularly sodium and potassium), dehydration, headache, nausea, and vomiting.
• Mannitol should be avoided in patients with severe heart failure, active intracranial bleeding, severe dehydration, or anuria unresponsive to a test dose.

Administration and Monitoring

• Before administration, healthcare providers should ensure adequate hydration and monitor fluid balance, electrolytes, and kidney function.
• The medication typically comes as a 20% solution and requires careful administration through a filter to prevent crystal formation from entering the bloodstream.
• Effects begin within 15-30 minutes and last 4-6 hours, requiring close monitoring throughout treatment, as noted in earlier studies 1.

Comparison with Other Treatments

• At equiosmotic dose (about 250 mOsm), mannitol and hypertonic saline (HS) have comparable efficacy to treat intracranial hypertension, with side effects that should be considered, including osmotic diuresis and hypernatremia, respectively 1.

From the FDA Drug Label

MANNITOL injection, for intravenous use ... WARNINGS AND PRECAUTIONS Renal Complications Including Renal Failure: Risk factors include pre-existing renal disease, conditions that put patients at risk for renal failure and concomitant use of nephrotoxic drugs or other diuretics. Fluid and Electrolyte Imbalances: Mannitol administration may obscure and intensify inadequate hydration or hypovolemia. Central Nervous System (CNS) Toxicity: Mannitol may increase cerebral blood flow and the risk of postoperative bleeding in neurosurgical patients. ADVERSE REACTIONS Most common adverse reactions are pulmonary congestion, fluid and electrolyte imbalance, acidosis, electrolyte loss, dryness of mouth, thirst, marked diuresis, urinary retention, edema, headache, blurred vision, convulsions, nausea, vomiting, rhinitis, arm pain, skin necrosis, thrombophlebitis, chills, dizziness, urticaria, dehydration, hypotension, tachycardia, fever and angina-like chest pains.

The health effects of mannitol include:

• Renal complications: risk of renal failure, especially with pre-existing renal disease or concomitant use of nephrotoxic drugs
• Fluid and electrolyte imbalances: may obscure and intensify inadequate hydration or hypovolemia
• Central nervous system (CNS) toxicity: may increase cerebral blood flow and the risk of postoperative bleeding in neurosurgical patients
• Common adverse reactions: pulmonary congestion, fluid and electrolyte imbalance, acidosis, electrolyte loss, and others The usage guidelines for mannitol are:
• Administration: for intravenous use only, do not add to whole blood for transfusion
• Dosage: depends on age, weight, and condition of the patient, with recommended dosages ranging from 0.25 to 2 g/kg body weight
• Contraindications: well-established anuria due to severe renal disease, severe pulmonary congestion or frank pulmonary edema, active intracranial bleeding, severe dehydration, and progressive heart failure or pulmonary congestion after institution of mannitol therapy 2

From the Research

Health Effects of Mannitol

• Mannitol has been used to treat cerebral edema and refractory intracranial hypertension in traumatic brain injury, subarachnoid hemorrhage, and stroke 3
• The drug can precipitate acute renal failure if serum osmolarity exceeds 320 mOsm/L 4
• Mannitol may cause side effects, prompting research into alternative treatments such as hypertonic saline (HS) 3
• HS has been shown to be safe and effective in reducing intracranial pressure (ICP), with no significant difference in efficacy compared to mannitol in small comparative trials 4

Usage Guidelines for Mannitol

• Mannitol can be used prophylactically, as a diagnostic aid, or as therapy for the oliguric state 5
• The diuretic properties of mannitol are useful in patients with refractory edema or intoxications by aspirin, barbiturates, or bromide 5
• Mannitol can be used to ameliorate intracranial hypertension or symptoms of dialysis dysequilibrium 5, 6
• The optimal dosage and administration of mannitol vary depending on the clinical situation, with equimolar doses of hypertonic agents (saline or mannitol) shown to be effective in treating intracranial hypertension after severe traumatic brain injury 7

Comparison with Hypertonic Saline

• Hypertonic saline appears to be safe, with serum sodium elevated to as high as 180 mEq/L in clinical settings without significant neurologic, cardiac, or renal injury 4
• Both mannitol and hypertonic saline are effective in reducing ICP, with no clinically significant difference noted in small comparative trials 4
• Repeat bolus dosing of 10% hypertonic saline and 20% mannitol appears to be similarly effective for treating intracranial hypertension in patients with severe traumatic brain injury 7