MANNITOL 25%
Clinical safety rating
safeOther diuretics may have additive effects Can cause fluid and electrolyte imbalances and pulmonary congestion.
Mannitol is an osmotic diuretic that increases plasma osmolarity, drawing water from intracellular and interstitial spaces into the intravascular compartment. In the kidney, it is filtered but not reabsorbed, increasing tubular fluid osmolarity and promoting water excretion. It also reduces intracranial and intraocular pressure by creating an osmotic gradient.
| Metabolism | Mannitol is not significantly metabolized; it is eliminated primarily unchanged by the kidney via glomerular filtration. |
| Excretion | Renal: >90% unchanged by glomerular filtration; biliary/fecal: <5%. |
| Half-life | Terminal elimination half-life: 0.25–1.7 hours; prolonged in renal impairment. |
| Protein binding | Negligible (<1%); does not bind significantly to plasma proteins. |
| Volume of Distribution | Vd: 0.5–0.7 L/kg; reflects distribution primarily in extracellular fluid. |
| Bioavailability | IV: 100%; not administered orally due to poor absorption and osmotic diarrhea. |
| Onset of Action | IV: Diuresis within 1–3 hours; reduction of intracranial pressure within 15–30 minutes. |
| Duration of Action | IV: Diuresis lasts 2–4 hours; reduction of intracranial pressure persists for 3–8 hours. |
| Molecular Weight | 182.17 |
1-2 g/kg (4-8 mL/kg) intravenously as a 25% solution over 30-60 minutes; may repeat every 6-8 hours as needed.
| Dosage form | INJECTABLE |
| Renal impairment | Contraindicated in patients with anuria or severe renal impairment (GFR < 20 mL/min). For GFR 20-50 mL/min, reduce dose by 50% and monitor serum osmolality and renal function closely. |
| Liver impairment | No specific Child-Pugh-based dose adjustments recommended; use with caution in hepatic impairment due to risk of volume overload and electrolyte disturbances. |
| Pediatric use | 0.25-2 g/kg (1-8 mL/kg) of 25% solution intravenously over 30-60 minutes; may repeat every 6-8 hours. Maximum dose 2 g/kg. Use with caution due to risk of fluid and electrolyte imbalance. |
| Geriatric use | Lower initial doses (0.5-1 g/kg) recommended; monitor renal function, fluid status, and electrolytes closely due to age-related decline in renal function and increased risk of volume overload. |
| 1st trimester | Mannitol is FDA pregnancy category C. Animal studies are inadequate. Use only if clearly needed. |
| 2nd trimester | Consider risks vs benefits; may cause maternal fluid/electrolyte disturbances affecting fetus. |
| 3rd trimester | May cause fetal dehydration or electrolyte imbalance; avoid in labor due to possible fetal effects. |
Clinical note
Other diuretics may have additive effects Can cause fluid and electrolyte imbalances and pulmonary congestion.
| FDA category | Animal |
| Placental transfer | Mannitol crosses the placenta; demonstrated in animal studies. |
| Breastfeeding | Excretion in breast milk unknown; caution due to potential for adverse effects in infant. |
| Lactation Rating | L3 |
| Teratogenic Risk | Mannitol crosses the placenta. Animal studies show no teratogenic effects at clinically relevant doses. In humans, osmotic diuresis may cause fetal electrolyte disturbances and dehydration, especially in the third trimester. Use only if clearly needed, weighing risks of maternal fluid overload against potential fetal harm. |
| Fetal Monitoring | Monitor maternal serum electrolytes (especially sodium, potassium, chloride), serum osmolality, urine output, fluid balance, and blood pressure. Fetal monitoring (heart rate, biophysical profile) is recommended in high-risk pregnancies. Observe for signs of maternal pulmonary edema or congestive heart failure. |
| Fertility Effects | No reported adverse effects on fertility in animal studies. No human data available. Mannitol is not expected to impact fertility at therapeutic doses. |
■ FDA Black Box Warning
No FDA black box warnings.
| Common Effects | edema |
| Serious Effects |
Anuria due to severe renal diseasePulmonary edema or congestionActive intracranial bleedingSevere dehydrationHypersensitivity to mannitol
| Precautions | May cause volume expansion and electrolyte disturbances (hyponatremia, hyperkalemia), Contraindicated in anuria due to severe renal disease, Risk of pulmonary congestion or edema in patients with cardiac disease, Monitor renal function, serum electrolytes, and fluid balance, May precipitate acute renal failure if used in high doses or in patients with pre-existing renal impairment, Can cause osmotic shifts leading to cellular dehydration or overexpansion |
| Food/Dietary | No specific food interactions. Maintain adequate hydration unless fluid restriction is indicated. |
| Clinical Pearls | Administer via central line due to high osmolality (1375 mOsm/L). Monitor serum osmolar gap to assess efficacy; target gap >10 mOsm/kg. Use with caution in patients with anuria, CHF, or pulmonary edema. May cause hypernatremia and hypokalemia. |
| Patient Advice | Report any headache, confusion, or shortness of breath immediately. · You may experience increased thirst and dry mouth. · This medication will increase your urine output. · Avoid taking other diuretics unless prescribed by your doctor. |
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