OSMITROL 15% IN WATER
Clinical safety rating
cautionComprehensive clinical and safety monograph for OSMITROL 15% IN WATER (OSMITROL 15% IN WATER).
Osmotic diuretic; increases plasma osmolality, drawing water from extravascular to intravascular space, thereby reducing intracranial and intraocular pressure.
| Metabolism | Minimal hepatic metabolism; excreted unchanged by the kidneys. |
| Excretion | Primarily renal excretion as unchanged drug; >97% eliminated by glomerular filtration within 24 hours. Minimal biliary/fecal elimination (<3%). |
| Half-life | Terminal elimination half-life is approximately 0.25–1.5 hours in patients with normal renal function; prolonged to 24–36 hours in anuria or severe renal impairment. |
| Protein binding | Negligible (<5%) protein binding; does not bind significantly to albumin or other plasma proteins. |
| Volume of Distribution | Volume of distribution is approximately 0.4–0.6 L/kg, confined primarily to extracellular fluid; little intracellular penetration. |
| Bioavailability | Not applicable (NA) due to intravenous administration only; oral bioavailability is negligible (not absorbed). |
| Onset of Action | Intravenous: Diuresis begins within 1–3 minutes; reduction of intracranial pressure occurs within 15–30 minutes after infusion start. |
| Duration of Action | Duration of diuresis is 2–6 hours; reduction of intracranial pressure lasts 3–8 hours depending on dose and renal function. Hemodynamic effects may persist longer in renal impairment. |
| Molecular Weight | 182.17 Da |
IV infusion of 50-200 g over 30-60 minutes as a 15% solution; typical adult dose is 1.5-2 g/kg every 6-8 hours.
| Dosage form | INJECTABLE |
| Renal impairment | Contraindicated in anuria or severe renal impairment (eGFR < 10 mL/min); use with caution in mild to moderate impairment, monitor serum osmolarity and renal function. |
| Liver impairment | No specific adjustment for Child-Pugh class; monitor for volume overload and electrolyte disturbances in severe hepatic impairment. |
| Pediatric use | IV infusion of 0.25-2 g/kg as a 15-20% solution over 30-60 minutes; dosing based on weight and clinical response. |
| Geriatric use | Start at lower end of dosing range; monitor for fluid overload, electrolyte imbalances, and renal function due to age-related decreased reserve. |
| 1st trimester | Osmotic diuretics like mannitol are generally avoided in the first trimester unless clearly necessary. Limited human data; animal studies suggest potential fetal harm from maternal hyperosmolarity and fluid shifts. Use only if benefit outweighs risk. |
| 2nd trimester | May be used with caution for specific indications (e.g., cerebral edema). Potential for maternal electrolyte imbalance and dehydration affecting placental perfusion. Monitor fluid and electrolyte status closely. |
| 3rd trimester | Use with caution; risk of maternal volume overload or dehydration. May cross placenta and cause fetal osmotic diuresis, leading to electrolyte disturbances in the neonate. Avoid near term unless absolutely needed. |
Clinical note
Comprehensive clinical and safety monograph for OSMITROL 15% IN WATER (OSMITROL 15% IN WATER).
| Placental transfer | Yes, mannitol crosses the placenta. It is distributed into fetal tissues and amniotic fluid. The degree of transfer is significant enough to produce fetal plasma concentrations approaching maternal levels, depending on dose and duration. |
| Breastfeeding | Mannitol is excreted into breast milk in small amounts. Oral bioavailability is low, so systemic effects in the infant are unlikely. However, potential for adverse effects such as diarrhea or electrolyte imbalance due to osmotic action in the infant's gut. Use caution, especially in neonates or infants with renal impairment. |
| Lactation Rating | L3 (Moderately safe; probably compatible but weigh risks) |
| Teratogenic Risk | Osmitrol (mannitol) 15% in water is FDA pregnancy category C. Animal studies have not been conducted; no well-controlled human studies exist. Mannitol is a high-osmolar agent that can cause maternal osmotic diuresis and fluid/electrolyte disturbances, potentially affecting fetal homeostasis. Risk in first trimester is unknown; in second and third trimesters, use only if clearly needed due to potential for maternal pulmonary edema or heart failure. |
| Fetal Monitoring | Monitor maternal serum electrolytes (sodium, potassium, chloride, bicarbonate), BUN, creatinine, and urine output before and during infusion. Monitor for signs of pulmonary edema or congestive heart failure (dyspnea, rales, weight gain). Fetal heart rate monitoring may be considered during administration in pregnant patients. |
| Fertility Effects | No studies on fertility effects in humans. In animal studies, mannitol at high doses may cause testicular degeneration, but relevance to human fertility is unknown. |
■ FDA Black Box Warning
None FDA-approved.
| Serious Effects |
Anuria due to severe renal diseasePulmonary edema or congestionActive intracranial bleeding (except during craniotomy)Severe dehydrationHyperosmolar comaKnown hypersensitivity to mannitol
| Precautions | Renal toxicity with high doses or prolonged use, Congestive heart failure exacerbation due to volume expansion, Electrolyte disturbances (hyponatremia, hypokalemia), Rapid infusion may cause hypotension and seizures, Use with caution in patients with anuria or pre-existing renal disease |
| Food/Dietary | No specific food interactions are documented. However, patients should maintain adequate hydration unless contraindicated. Diets high in sodium may exacerbate hypernatremia risk. Monitor fluid and electrolyte intake as directed by the clinician. |
| Clinical Pearls | OSMITROL 15% IN WATER is a hypertonic solution for intravenous administration. Monitor serum sodium and osmolality closely to avoid hypernatremia and hyperosmolality. Ensure patency of IV line as extravasation can cause tissue necrosis. Use with caution in patients with renal impairment, heart failure, or hypovolemia. Rapid infusion can cause hemolysis. May cause osmotic diuresis leading to electrolyte depletion; monitor potassium and magnesium. |
| Patient Advice | This medication is given intravenously to reduce brain swelling or lower eye pressure. · Report any pain, redness, or swelling at the injection site immediately. · You may experience increased thirst or urination; this is expected due to the medication's effects. · Inform your healthcare provider if you have a history of kidney problems, heart failure, or dehydration. · Regular blood tests will be performed to monitor your electrolyte levels and kidney function. |
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