Mannitol
Dosage & Administration Guidelines
| Species | Route | Dose | Frequency | Duration & Clinical Notes |
|---|---|---|---|---|
| Dog | IV | 0.25-1 g/kg (as 20% solution) or 1-2 g/kg for cerebral edema | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. |
| Cat | IV | 0.25-1 g/kg (as 20% solution) | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. |
| Horse | IV | 0.25-1 g/kg (as 20% solution) | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. |
| Cattle | IV | 0.25-1 g/kg (as 20% solution) | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. |
| Small Ruminants (sheep, goats) | IV | 0.25-1 g/kg (as 20% solution) | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. |
| Rabbit | IV | 0.25-1 g/kg (as 20% solution) | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. |
| Birds (pet birds) | IV | 0.25-1 g/kg (as 20% solution) | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. Extrapolated from other species. |
| Exotic mammals (ferrets, guinea pigs) | IV | 0.25-1 g/kg (as 20% solution) | Administered over 20-30 minutes; may repeat every 4-6 hours if needed | Duration: As needed, usually 24-72 hours Notes: Use a 20% solution for IV administration. Monitor serum osmolality and renal function. Avoid extravasation. Extrapolated from other species. |
Clinical Indications & Species Uses
- Osmotic diuresis
- Reduction of intracranial pressure
- Reduction of intraocular pressure
- Acute renal failure (oliguric)
- Forced diuresis for toxin excretion
- Reduction of intracranial pressure and cerebral edema (e.g., traumatic brain injury, brain tumors)
- Reduction of intraocular pressure in acute glaucoma
- Promotion of diuresis in acute renal failure (oliguric) to maintain urine output
- To enhance excretion of toxic substances (e.g., salicylates, bromides) by forced diuresis
- Adjunctive therapy in acute hemolytic reactions to prevent renal damage
- Reduction of intracranial pressure and cerebral edema
- Reduction of intraocular pressure in acute glaucoma
- Promotion of diuresis in acute renal failure (oliguric)
- To enhance excretion of toxic substances
- Reduction of intracranial pressure and cerebral edema (e.g., head trauma)
- Reduction of intraocular pressure in acute glaucoma
- Promotion of diuresis in acute renal failure
- Treatment of acute laminitis (historically, though efficacy is debated)
- Reduction of intracranial pressure and cerebral edema (e.g., polioencephalomalacia)
- Reduction of intraocular pressure in acute glaucoma
- Promotion of diuresis in acute renal failure
- Reduction of intracranial pressure and cerebral edema
- Reduction of intraocular pressure in acute glaucoma
- Promotion of diuresis in acute renal failure
- Reduction of intracranial pressure and cerebral edema
- Reduction of intraocular pressure in acute glaucoma
- Promotion of diuresis in acute renal failure
- Reduction of intracranial pressure and cerebral edema in small mammals (e.g., ferrets, guinea pigs) and reptiles (e.g., turtles with edema). Use with caution and based on extrapolated doses.
Pharmacology & Mechanism of Action
Drug Class: Osmotic Diuretic | Pharmacological Group: Polyol (sugar alcohol)
Mechanism of Action: Mannitol is a six-carbon sugar alcohol that is pharmacologically inert. When administered intravenously, it is freely filtered by the glomerulus but not reabsorbed by the renal tubules, creating an osmotic gradient that prevents water reabsorption, thereby increasing urine flow and excretion of water and electrolytes. It also increases renal medullary blood flow and washout of medullary solutes, further enhancing diuresis. In the central nervous system, mannitol increases plasma osmolality, drawing water from brain tissue into the intravascular compartment, thereby reducing intracranial pressure and cerebral edema. Similarly, it reduces intraocular pressure by creating an osmotic gradient that draws fluid from the eye into the plasma.
Pharmacodynamics: Mannitol produces a rapid onset of diuresis within 1-3 hours after intravenous administration, with peak effect at 1-2 hours. The diuretic effect is directly proportional to the dose and the amount of mannitol excreted in the urine. It increases urine volume and excretion of sodium, potassium, chloride, and other solutes. In the brain, the reduction in intracranial pressure occurs within 15-30 minutes and lasts for 2-6 hours. The reduction in intraocular pressure occurs within 30-60 minutes and lasts for 4-6 hours. Mannitol does not cross the blood-brain barrier under normal conditions, but in areas of disrupted blood-brain barrier, it may enter the brain and potentially cause a rebound increase in intracranial pressure.
β‘ Pharmacokinetics Summary
Available Formulations & Strengths
Contraindications & Clinical Warnings
- Anuria due to severe renal disease
- Severe dehydration or hypovolemia
- Active intracranial bleeding (except during craniotomy)
- Severe pulmonary congestion or edema
- Congestive heart failure
- Known hypersensitivity to mannitol
- Use with caution in patients with renal impairment; monitor urine output and renal function.
- Monitor serum osmolality and electrolytes (especially sodium and potassium) during therapy.
- Avoid extravasation; mannitol is hypertonic and can cause tissue necrosis.
- Use with caution in patients with cardiac disease; may precipitate fluid overload.
- Rapid administration may cause osmotic nephrosis and acute tubular necrosis.
- In patients with head trauma, monitor for rebound increase in intracranial pressure.
- Do not administer with blood products; may cause agglutination.
- Use with caution in neonates and geriatric patients.
- In food animals, observe withdrawal times.
Adverse Effects & Reactions
Common:
- Electrolyte imbalances (hyponatremia, hypernatremia, hypokalemia)
- Dehydration
- Headache (in humans; not directly observable in animals)
- Nausea and vomiting
- Diuresis leading to polyuria and polydipsia
Serious / Severe:
- Acute renal failure (especially with high doses or pre-existing renal disease)
- Pulmonary edema
- Congestive heart failure
- Intracranial hemorrhage (rebound)
- Osmotic nephrosis
- Tissue necrosis at injection site (extravasation)
Rare:
- Allergic reactions (urticaria, anaphylaxis)
- Thrombophlebitis
- Metabolic acidosis
- Hyperosmolality
Key Drug Interactions
| Interacting Drug / Class | Clinical Effect & Mechanism | Severity |
|---|---|---|
| Lithium | Mannitol may increase renal excretion of lithium, reducing its efficacy. | Moderate |
| Other diuretics (e.g., furosemide) | Additive diuretic effects may lead to excessive fluid and electrolyte loss. | Moderate |
| Aminoglycosides | Increased risk of nephrotoxicity due to enhanced renal blood flow and tubular delivery. | Moderate |
| Corticosteroids | May increase risk of electrolyte imbalances (e.g., hypokalemia). | Mild |
| Neuromuscular blocking agents | Mannitol may enhance the effects of neuromuscular blockers by altering electrolyte balance. | Mild |
Overdose & Toxicity Management
Signs of Toxicity:
- Hyperosmolality
- Hyponatremia or hypernatremia
- Dehydration
- Pulmonary edema
- Congestive heart failure
- Acute renal failure
- Cerebral edema (rebound)
- Coma
Emergency Treatment Protocol: Treatment is primarily supportive. Discontinue mannitol immediately. Monitor vital signs, serum electrolytes, osmolality, and renal function. Administer fluids to correct dehydration or electrolyte imbalances as needed. In severe cases, hemodialysis may be required to remove mannitol and correct fluid and electrolyte disturbances. Provide symptomatic treatment for pulmonary edema or heart failure if they occur.
Food Animal Withdrawal Times
Mannitol is not a food additive and is used therapeutically. Withdrawal times are not established, but due to its rapid elimination, a withdrawal period of 24 hours is often recommended for meat and milk in food animals to be safe. Consult regulatory guidelines.
Storage, Handling & Regulatory Information
Storage Temperature: Store at controlled room temperature (20-25Β°C, excursions permitted to 15-30Β°C).
Handling & Special Conditions: Protect from freezing. Do not use if solution is discolored or contains crystals. If crystallization occurs, warm to dissolve before use.
Dispensing Status: Prescription Required (Rx Only)
Approval Status: Approved for human use; not specifically approved for veterinary use, but widely used in veterinary medicine.
Extra-Label (Off-Label) Use: In the US, mannitol is approved for use in humans and is used extra-label in veterinary medicine. Extra-label use in food animals requires a valid veterinary-client-patient relationship and must comply with AMDUCA regulations. Withdrawal times must be observed.
Clinical Pearls & Practice Notes
References & Literature
- π Plumb's Veterinary Drug Handbook
- π Papich Veterinary Pharmacology and Therapeutics
- π Compendium of Veterinary Products (CVP)