Mannitol 20%

Mannitol 20% 

Mannitol 20% is a hypertonic intravenous solution containing 200 grams of mannitol per liter (i.e., 20 g per 100 mL). It is a powerful osmotic diuretic and is commonly used in emergency and critical care to:

• Lower intracranial pressure (ICP) due to cerebral edema

• Reduce intraocular pressure (IOP) in acute glaucoma

• Promote urine production in early acute kidney failure

• Assist in eliminating toxic substances through the kidneys

Mechanism of Action

Mannitol works by drawing water out of cells and into the bloodstream through osmosis. This:

• Reduces swelling in the brain or eyes

• Increases plasma volume and renal blood flow

• Promotes diuresis (urine production)

Uses of Mannitol 20%

1. Cerebral edema (brain swelling due to trauma, stroke, or infection)

2. Raised intraocular pressure (e.g., acute glaucoma, before eye surgery)

3. Oliguria in acute kidney injury (to test or promote kidney function)

4. Forced diuresis in drug poisoning (e.g., salicylate or barbiturate overdose)

Typical Dosage (Adults)

• Cerebral edema/intracranial pressure:
  1.5–2 g/kg as a slow IV infusion over 30–60 minutes
  Repeat every 6–8 hours if needed

• Intraocular pressure:
  1.5–2 g/kg IV 30–60 minutes before surgery or treatment

• Renal test dose:
  0.2 g/kg over 3–5 minutes to test kidney response

Note: Mannitol 20% is administered intravenously through a filter to avoid injecting crystals.

Side Effects

Common:

• Headache

• Nausea

• Vomiting

• Dizziness

Serious (requires immediate attention):

• Electrolyte imbalance (low sodium or potassium)

• Pulmonary edema (especially in heart failure)

• Heart strain (due to fluid shift)

• Confusion or seizures (especially in kidney failure)

Contraindications (Do Not Use If…)

• Complete kidney failure (anuria)

• Severe heart failure or lung congestion

• Severe dehydration

• Active brain bleeding (except during surgery)

• Severe electrolyte imbalances

• Known allergy to mannitol

Precautions and Monitoring

• Always check for crystals in the solution; warm gently to dissolve if needed.

• Must use a filter needle or filter IV set.

• Monitor:

  • Serum electrolytes (sodium, potassium)

  • Kidney function (urine output, creatinine)

  • Fluid balance and vital signs

  • Signs of heart or lung complications

Storage and Handling

• Store below 25°C; do not freeze.

• If crystals form, warm the solution to dissolve and shake gently.

• Do not use if crystals persist or solution is discolored.

Key Differences from Mannitol 10%