Usage
- Glycerin + Mannitol is prescribed for the treatment of cerebral edema (brain swelling) and raised intracranial pressure (ICP). It is also used to reduce elevated intraocular pressure (IOP) and can be employed in the prevention and treatment of the oliguric phase of acute renal failure.
- Pharmacological classification: Osmotic diuretic.
- Mechanism of Action: This combination exerts its effect by increasing the osmotic pressure of plasma, drawing fluid out of the brain and eyes into the vascular compartment. This subsequently increases urine production, leading to reduced ICP and IOP.
Alternate Names
- Glycerol + Mannitol
- Brand Names: Neurotol, Critol-G (Note: Brand names can vary regionally. This list may not be exhaustive.)
How It Works
- Pharmacodynamics: Glycerin and mannitol create an osmotic gradient across the blood-brain barrier and the blood-aqueous barrier, leading to fluid shifts from the brain and eyes into the plasma.
- Pharmacokinetics: Both drugs are administered intravenously. Mannitol is primarily excreted unchanged in the urine. Glycerin can be metabolized in the liver or excreted unchanged by the kidneys.
- Mode of Action: Osmotic gradient creation.
- Receptor binding, enzyme inhibition, or neurotransmitter modulation: Not applicable.
- Elimination pathways: Primarily renal excretion for both, with some hepatic metabolism for glycerin.
Dosage
Standard Dosage
Adults:
- Cerebral Edema/Raised ICP: 1-2 g/kg of mannitol combined with an equal dose of glycerin, infused intravenously over 30-60 minutes. This can be repeated every 6-8 hours as needed.
- Elevated Intraocular Pressure: 1.5-2 g/kg of mannitol combined with an equal dose of glycerin, infused intravenously over 30-60 minutes. Preoperatively, administer 1-1.5 hours before surgery.
Children:
- Cerebral Edema/Raised ICP: 0.5-1 g/kg of each drug infused over 30-60 minutes. (For severe encephalopathies, such as Reye syndrome, 20% solutions of each drug at 0.5-1.0 g/kg may be used).
- Elevated IOP: 1.5-2 g/kg of a 20% solution of mannitol with an equivalent glycerin dose infused over 30-60 minutes.
- Pediatric Safety Considerations: Close monitoring of fluid and electrolyte balance is crucial in children due to their higher susceptibility to dehydration and electrolyte disturbances.
Special Cases:
- Elderly Patients: Close monitoring for fluid and electrolyte imbalances, and renal function.
- Patients with Renal Impairment: Dose adjustments are usually necessary.
- Patients with Hepatic Dysfunction: Caution is advised with Glycerin due to its potential hepatic metabolism.
- Patients with Comorbid Conditions: Careful monitoring is essential for patients with cardiac conditions or diabetes.
Clinical Use Cases
- Intubation: Can be used to decrease ICP before intubation in patients with neurological conditions.
- Surgical Procedures: Employed to decrease IOP before ophthalmic surgery and to reduce ICP prior to neurosurgical procedures.
- Mechanical Ventilation: May be used in mechanically ventilated patients with raised ICP.
- Intensive Care Unit (ICU) Use: Frequently administered for ICP management in ICU settings.
- Emergency Situations: Used for emergent reduction of ICP and IOP.
Dosage Adjustments:
- Adjust based on patient response, serum osmolality, and renal function.
Side Effects
Common Side Effects
- Headache
- Nausea
- Vomiting
- Dizziness
- Chills
- Infusion site reactions
Rare but Serious Side Effects
- Severe dehydration
- Electrolyte imbalances (hyponatremia, hypokalemia)
- Pulmonary edema
- Cardiac decompensation
- Seizures
- Allergic reactions (rash, hives, swelling)
- Kidney injury
Long-Term Effects
- Chronic kidney disease (with prolonged or high-dose use)
Adverse Drug Reactions (ADR)
- Anaphylaxis (rare but potentially fatal)
- Severe electrolyte imbalances
Contraindications
- Anuria
- Severe pulmonary edema or congestion
- Active intracranial bleeding (except during craniotomy)
- Severe dehydration
- Hypersensitivity to mannitol or glycerin
- Severe renal failure
- Congestive heart failure
Drug Interactions
- Other diuretics (additive effects)
- Nephrotoxic drugs (increased risk of kidney damage)
- Medications affecting electrolyte levels (e.g., lithium, digoxin)
- Drugs that increase blood volume (e.g., corticosteroids)
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (Mannitol, Glycerin) - Use only if potential benefits outweigh the risks.
- Limited data exists on use during pregnancy.
- Excretion in breast milk is unknown for both drugs. Caution advised during breastfeeding.
Drug Profile Summary
- Mechanism of Action: Creates an osmotic gradient.
- Side Effects: Headache, nausea, vomiting, dizziness, electrolyte imbalances, dehydration.
- Contraindications: Anuria, severe pulmonary edema, active intracranial bleeding, severe dehydration, hypersensitivity.
- Drug Interactions: Other diuretics, nephrotoxic drugs.
- Pregnancy & Breastfeeding: Category C - use with caution.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: Serum osmolality, electrolytes, renal function, ICP/IOP, urine output, cardiac and pulmonary function.
Popular Combinations
- Not typically combined with other drugs, often used as standalone therapy for rapid reduction of ICP/IOP.
Precautions
- General Precautions: Monitor fluid and electrolyte balance, renal function, and cardiac/pulmonary status closely.
- Specific Populations: See special cases under Dosage.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Glycerin + Mannitol?
A: Dosage varies according to the patient’s age, condition, and response to therapy. Refer to the detailed dosage guidelines above.
Q2: What are the primary uses of this combination?
A: Primarily used to treat cerebral edema, elevated intracranial pressure (ICP), and raised intraocular pressure (IOP). Also used to prevent/treat the oliguric phase of acute renal failure.
Q3: What are the common side effects?
A: Headache, nausea, vomiting, dizziness, and chills.
Q4: What are the serious side effects I should be aware of?
A: Severe dehydration, electrolyte imbalances, pulmonary edema, cardiac decompensation, seizures, allergic reactions, and kidney injury.
Q5: Are there any contraindications to using Glycerin + Mannitol?
A: Yes, including anuria, severe pulmonary edema, active intracranial bleeding, severe dehydration, and hypersensitivity to either drug component.
Q6: Can this combination be used in pregnant or breastfeeding women?
A: Pregnancy Safety Category C for both drugs. Use with caution only if benefits outweigh risks. Consult with specialists. Limited data regarding breast milk excretion.
Q7: What are the key monitoring parameters during therapy?
A: Serum osmolality, electrolytes (sodium, potassium), renal function, ICP/IOP, urine output, cardiac and pulmonary function.
Q8: How does Glycerin complement Mannitol in treating cerebral edema?
A: Glycerin helps to sustain the reduction in ICP achieved by mannitol and may reduce the risk of “rebound edema” sometimes seen with mannitol alone.
Q9: What should I do in case of suspected overdose?
A: Immediately discontinue the infusion and initiate supportive care, including management of dehydration, electrolyte imbalances, and potential renal impairment.
Q10: What is the mechanism of action of Glycerin + Mannitol?
A: Both are osmotic diuretics, creating an osmotic gradient that draws water out of tissues and into the vascular space, increasing urine output and reducing ICP and IOP.
