Mannitol

# Mannitol ## Overview - **Classification**: Osmotic Diuretic - **Mechanism**: Increases plasma osmolarity, drawing water from extravascular spaces (including brain) into the intravascular space, increasing blood volume and renal blood flow. ## Primary Indications 1. **Reduction of Intracranial Pressure (ICP)** - Due to cerebral edema 2. **Reduction of Intraocular Pressure (IOP)** - Prior to ophthalmic surgery 3. **Promotion of Diuresis** - In prevention and treatment of oliguric phase of acute renal failure ## Adult Dosing ### Standard Dosing **Reduction of ICP/IOP** - **Dose**: **0.25-1 g/kg** (typically as 20% solution) - **Frequency**: Every **6-8 hours** as needed - **Route**: Intravenous infusion over **30-60 minutes** - **Maximum**: **200 g/24 hours** **Promotion of Diuresis (Oliguria Prophylaxis/Treatment)** - **Test Dose**: **0.2 g/kg** IV over **3-5 minutes** - **If diuresis occurs (30-50 mL/hr for 2-3 hours)**: - **Dose**: **0.2-0.5 g/kg** - **Frequency**: Every **4-6 hours** as needed - **Route**: Intravenous infusion over **30-60 minutes** - **Maximum**: **100 g/24 hours** ### Dose Adjustments - **Renal Impairment**: - **CrCl < 30 mL/min**: Use with extreme caution or contraindicated. Risk of accumulation and worsening heart failure. - If used, start with a test dose. Discontinue if diuresis does not occur. - **Hepatic Impairment**: No specific dose adjustments required. - **Elderly Patients**: - Start at lower end of dosing range due to potential for decreased renal function. - Monitor closely for dehydration and electrolyte imbalance. ## Pediatric Dosing ### Neonates (0-28 days) - **Indication**: Rarely used, consider only in life-threatening cerebral edema. - **Dose**: **0.25-0.5 g/kg/dose** (e.g., 20% solution) - **Frequency**: Every **6-8 hours** if absolutely necessary - **Route**: Intravenous infusion over **20-30 minutes** - **Maximum**: **1 g/kg/day** - **Special Notes**: High risk of IVH, rebound ICP, and electrolyte disturbances due to immature blood-brain barrier. Monitor vital signs and fluid status diligently. ### Infants (1-12 months) - **Indication**: Cerebral edema/increased ICP. - **Test Dose**: **0.2 g/kg** IV over **3-5 minutes** - **Full Dose**: **0.25-1 g/kg/dose** (e.g., 20% solution) - **Frequency**: Every **6-8 hours** as needed - **Route**: Intravenous infusion over **30-60 minutes** - **Maximum**: **1.5 g/kg/day** or **50 g/day**, whichever is less. ### Children (1-12 years) - **Indication**: Cerebral edema/increased ICP. - **Test Dose**: **0.2 g/kg** IV over **3-5 minutes** - **Full Dose**: **0.25-1 g/kg/dose** (e.g., 20% solution) - **Frequency**: Every **6-8 hours** as needed - **Route**: Intravenous infusion over **30-60 minutes** - **Maximum**: **1.5 g/kg/day** or **100 g/day**, whichever is less. ### Adolescents (13-18 years) - **Dose**: Generally follow adult dosing for respective indications. - **Route**: Intravenous infusion over **30-60 minutes** - **Maximum**: **200 g/24 hours** for ICP/IOP; **100 g/24 hours** for diuresis. ## Safety Information ### Contraindications - **Absolute**: Anuria (unless test dose is negative), severe dehydration, active intracranial bleeding (unless prior to craniotomy), severe pulmonary congestion or edema, progressive heart failure. - **Relative**: Severe renal disease, significant fluid/electrolyte imbalance. ### Common Adverse Effects - **Very Common (>10%)**: Fluid/electrolyte imbalance (dehydration, hyponatremia, hypernatremia, hyperkalemia), thirst, headache, nausea, vomiting. - **Common (1-10%)**: Dizziness, blurred vision, chills, hypotension, skin rash. - **Serious but Rare**: Rebound ICP, acute kidney injury (osmotic nephrosis), congestive heart failure, pulmonary edema, anaphlaxis. ### Key Drug Interactions - **Loop Diuretics**: Enhanced diuretic and natriuretic effects. Monitor for excessive fluid/electrolyte loss. - **Nephrotoxic Drugs**: May increase risk of renal toxicity, especially with prolonged use. Monitor renal function closely. - **Digoxin**: Mannitol-induced hypokalemia can potentiate digoxin toxicity. Monitor potassium and digoxin levels. ## Monitoring & Follow-up - **Before Treatment**: Baseline serum electrolytes (Na, K), renal function (BUN, Cr), serum osmolality, and fluid status. - **During Treatment**: - **ICP/IOP**: Neurological status, ICP measurements (if available), IOP. - **Fluid Balance**: Strict intake and output, daily weights. - **Electrolytes**: Serum Na, K, Mg, Cl, serum osmolality every **4-6 hours** or as clinically indicated. - **Renal Function**: BUN, Cr daily. - **Clinical Signs**: Watch for signs of dehydration (e.g., dry mucous membranes, decreased skin turgor), worsening pulmonary edema (e.g., dyspnea, crackles), or rebound ICP (e.g., deteriorating mental status, pupillary changes). ## Clinical Pearls - 💡 **Filter Required**: Always administer mannitol solutions (especially 20% or 25%) using a **filter needle** during preparation and an **in-line filter** during infusion to prevent infusion of mannitol crystals. - 💡 **Warm to Dissolve**: If crystals are present, warm the solution in a warm water bath and shake vigorously. Cool to body temperature before administration. - 💡 **Rebound Effect**: Monitor for rebound increases in ICP 6-10 hours post-dose, especially if blood-brain barrier is disrupted. - 💡 **Fluid Status**: Carefully assess hydration status and correct dehydration before mannitol administration. Over-rapid infusion can exacerbate hypotension. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.