Manisol

Indications

Mannitol is a sugar alcohol given as an intravenous infusion (commonly 10% or 20% solution) in hospital. It is used to reduce raised pressure inside the skull (cerebral oedema) after head injury, stroke or brain tumours, to lower high pressure inside the eye (for example in acute glaucoma or before eye surgery), to promote urine flow in certain situations, and to help remove some toxins through the kidneys. An inhaled powder form is used in some lung conditions, but that is a different product.

How It Works

Mannitol stays in the bloodstream and is not absorbed into cells. This makes the blood more concentrated, so water is drawn out of swollen tissues such as the brain and eye back into the blood. The kidneys filter mannitol but cannot reabsorb it, so it carries extra water out in the urine (osmotic diuresis).

Dosage and Administration

Given only by a doctor or nurse as an intravenous infusion, usually through a filter. The dose and rate are calculated by the doctor according to body weight, the condition being treated, kidney function and blood tests, and are given as prescribed. Crystals that form in the solution in cold conditions must be fully redissolved by warming before use.

Interactions

• It can increase the effects of other diuretics and change blood levels of Lithium.
• Use with nephrotoxic drugs such as Aminoglycosides or Ciclosporin may increase the risk of kidney injury.
• Blood should not be given through the same line.

Contraindications

• Kidney failure with no urine output (anuria) after a test dose
• Severe dehydration
• Severe heart failure or fluid in the lungs
• Active bleeding inside the skull, except during surgery
• Allergy to mannitol

Side Effects

• Fluid and salt imbalance: high or low sodium, low or high potassium
• Dehydration, thirst, dry mouth
• Headache, nausea, vomiting, dizziness
• Fluid overload with breathlessness in people with heart problems
• Pain or tissue damage if the drip leaks out of the vein
• Rarely, kidney injury or allergic reactions

Tell the nurse or doctor at once if you develop breathlessness, chest pain, confusion, fits, a marked fall in urine output, severe thirst, a rash or swelling of the face, or pain and swelling at the drip site.

Pregnancy and Lactation

Mannitol is used in pregnancy and breastfeeding only when the doctor judges the benefit outweighs the risk.

Precautions and Warnings

• Kidney function, urine output, blood salts and fluid balance are monitored closely.
• A small test dose may be given first if kidney function is poor.
• Extra care in heart disease and older people.
• Use only a clear solution with no crystals.

Overdose

Too much mannitol can cause severe fluid and salt imbalance, dehydration, fluid overload, confusion, fits or kidney injury. The infusion is stopped and the medical team corrects fluids and salts; dialysis may be used if needed.

Therapeutic Class

Osmotic diuretic

Storage

Hospital product: store as directed on the pack, usually between 20°C and 30°C. Do not refrigerate or freeze, because crystals may form. Use only if clear and the container is intact.