Osmotic diuretics mannitol

Intravenous administration of mannitol (osmotic diuretic) may be considered at a dose of 0.25-2 g/kg over 30-60 minutes. 

Mannitol Osmotic diuretic Increases effective circulating volume and RBF May increase GFR May help to flush away debris that may obstruct the tubules May scavenge oxygen radicals Constant i.v. infusion required May induce hyperosmolality High doses may precipitate acute renal failure... 

Manufacture of vitamin C starts with the conversion of sorbitol to L-sorbose. Sorbitol and xyHtol have been used for parenteral nutrition following severe injury, bums, or surgery (246). An iron—sorbitol—citric acid complex is an intramuscular bematinic (247). Mannitol administered intravenously (248) and isosorbide administered orally (249) are osmotic diuretics. Mannitol hexanitrate and isosorbide dinitrate are antianginal dmgs (see Cardiovascular agents). 

The osmotic diuretics urea and mannitol are administered intravenously (IV), whereas glycerin and isosorbide are administered orally Administration by the IV route may result in a rapid fluid and electrolyte imbalance, especially when these drugs are administered before surgery with the patient in a fasting state ... 

The osmotic diuretics are contraindicated in patients with known hypersensitivity to the drags, electrolyte imbalances, severe dehydration, or anuria and those who experience progressive renal damage after instituting therapy (mannitol). Mannitol is contraindicated in patients with active intracranial bleeding (except during craniotomy). 

Mannitol is an agent that may be used in patients with I impending cerebral herniation. Mannitol is an osmotic diuretic that shifts brain osmolarity from the brain to the blood. Doses of 100 g (1-2 g/kg) as an intravenous bolus should be used. Repeated doses typically are not recommended because mannitol may diffuse into damaged brain tissue, leading to rebound increased ICP.21... 

Osmotic diuretics such as mannitol act on the proximal tubule and, in particular, the descending limb of the Loop of Henle — portions of the tubule permeable to water. These drugs are freely filtered at the glomerulus, but not reabsorbed therefore, the drug remains in the tubular filtrate, increasing the osmolarity of this fluid. This increase in osmolarity keeps the water within the tubule, causing water diuresis. Because they primarily affect water and not sodium, the net effect is a reduction in total body water content more than cation content. Osmotic diuretics are poorly absorbed and must be administered intravenously. These drugs may be used to treat patients in acute renal failure and with dialysis disequilibrium syndrome. The latter disorder is caused by the excessively rapid removal of solutes from the extracellular fluid by hemodialysis. 

The answer is b. (Hardman, pp 695-697.) A significant increase in the amount of any osmotically active solute in voided urine is usually accompanied by an increase in urine volume Osmotic diuretics affect diuresis through this principle. The osmotic diuretics (such as mannitol) are nonelectrolytes that are freely filtered at the glomerulus, undergo limited re absorption by the renal tubules, retain water in the renal tubule, and promote an osmotic diuresis, generally without significant Na excretion. Ln addition, these diuretics resist alteration by metabolic processes. 

Most of the lithium is eliminated in the urine, the first phase of the elimination being 6-8 hours after administration, followed by a slower phase which may last for 2 weeks. Sodium-depleting diuretics such as frusemide, ethacrynic acid and the thiazides increase lithium retention and therefore toxicity, while osmotic diuretics as exemplified by mannitol and urea enhance lithium excretion. The principal side effects of lithium are summarized in Table 8.1. 

Forced diuresis is occasionally useful. It may cause volume overload or electrolyte disturbances. Forced diuresis is useful for phenobarbital, bromides, lithium, salicylate, or amphetamines overdoses. Do not use for tricyclic antidepressants, sedative-hypnotics, or highly protein-bound medications. The most common agents employed are furosemide and osmotic diuretics with mannitol. 

Mannitol (OsmitroL others) [Osmotic Diuretic] Uses Cerebral edema, T lOP/ICP, renal impair, poisonings Action Osmotic diuretic Dose Test dose 0.2 g/kg/dose IV over 3-5 min if no diuresis w/in 2 h, D/C Oliguria 50-100 g IV over 90 min T lOP 0.5-2 g/kg IV over 30 min Cerebral edema 0.25-1.5 g/kg/dose IV >30 min Caution [C, ] w/ CHF or volume overload Contra Anuria, dehydration, HE, PE Disp Inj SE May exacerbate CHF, N/V/D Interactions t Effects OF cardiac glycosides X effects OF barbiturates, imipramine, Li, salicylates EMS Monitor ECG for hypo-/hyperkalemia (T wave changes) OD May cause dehydration, t urine frequency/amount hypotension and CV collapse symptomatic and supportive... 

Osmotic diuretics such as mannitol are readily filtered in the glomeruli, but they are hardly subject to tubular reabsorption. For this reason the osmotic... 

Interest has developed in the use of l,4 3,6-dianhydro-D-glucitol as an orally administered, osmotic diuretic. It has been examined in the laboratory," 1 and clinically"5 in patients having cirrhosis of the liver. It was found to be similar in effectiveness to intravenous D-mannitol."5 Its use in diuretic compositions has been patented.116... 

Because water is reabsorbed in direct proportion to salt reabsorption in the proximal tubule, luminal fluid osmolality remains nearly constant along its length, and an impermeant solute like inulin rises in concentration as water is reabsorbed. If large amounts of an impermeant solute such as mannitol (an osmotic diuretic) are present in the tubular fluid, water reabsorption causes the concentration of the solute and osmolality of tubular fluid to rise, eventually preventing further water reabsorption. 

The proximal tubule and descending limb of Henle s loop are freely permeable to water (Table 15-1). Any osmotically active agent that is filtered by the glomerulus but not reabsorbed causes water to be retained in these segments and promotes a water diuresis. Such agents can be used to reduce intracranial pressure and to promote prompt removal of renal toxins. The prototypic osmotic diuretic is mannitol. 

Osmotic diuretics are used to increase water excretion in preference to sodium excretion. This effect can be useful when avid Na + retention limits the response to conventional agents. It can be used to maintain urine volume and to prevent anuria that might otherwise result from presentation of large pigment loads to the kidney (eg, from hemolysis or rhabdomyolysis). Some oliguric patients do not respond to osmotic diuretics. Therefore, a test dose of mannitol (12.5 g intravenously) should be given before starting... 

Osmotic diuretics alter Starling forces so that water leaves cells and reduces intracellular volume. This effect is used to reduce intracranial pressure in neurologic conditions and to reduce intraocular pressure before ophthalmologic procedures. A dose of 1-2 g/kg mannitol is administered intravenously. Intracranial pressure, which must be monitored, should fall in 60-90 minutes. 

Mannitol is rapidly distributed in the extracellular compartment and extracts water from cells. Prior to the diuresis, this leads to expansion of the extracellular volume and hyponatremia. This effect can complicate heart failure and may produce florid pulmonary edema. Headache, nausea, and vomiting are commonly observed in patients treated with osmotic diuretics. 

Peds. Cardiac arrest w/ torsades 25-50 mg/kg/dose IV Caution [B, +] Contra Heart block Disp Inj 10, 20, 40, 80, 125, 500 mg/mL bulk powder SE CNS depression, D, flushing, heart block Interactions T CNS depression W/ antidepressants, antipsychotics, anxiolytics, barbiturates, hypnodcs, narcotics EtOH T neuromuscular blockade W/ aminoglycosides, atracurium, gallamine, pancuronium, tubocurarine, vecuronium EMS Monitor ECG for changes Mannitol (Osmitrol) [Osmotic Diuretic] Uses Tx cerebral edema (T ICP) Action Diuretic Dose Adults. 0.5-2 g/kg slow IV Peds. 0.2-0.5 g/kg IV over 60 min Caution [C, ] Contra Pulm edema, CHF, cerebral bleeding Disp Inj, sol 5% (50 mg/mL) 10% (100 mg/mL) 15% (150 mg/mL) 20% (200 mg/mL) 25% (250 mg/mL) SE N/V, HA, dizziness, edema, blurred vision, diuresis, dehydration Interactions Interferes w/ blood transfusions EMS Use caution to prevent extravasation (use large vein) rebound T in ICP has been noted about 12 h post administration... 

As their name suggests, osmotic diuretics such as mannitol (Osmitrol), isosorbide (Ismotic), and glycerin (Osmoglyn) draw fluid from the tissues of the body through principles of osmosis. Osmotic diuretics are typically given to treat or prevent acute renal failure (kidney failure). They may also be used to relieve intracranial pressure (swelling of the brain) in cases of head injury or hydrocephalus. 

Osmotic diuretics are poorly absorbed, which means that they must be given parenterally. If administered orally, mannitol causes osmotic diarrhea. Mannitol is not metabolized and is excreted primarily by glomerular filtration within 30-60 minutes, without any important tubular reabsorption or secretion. 

These include mannitol and sorbitol which act mainly in the proximal tubules to prevent reabsorption of water. These polyhydric alcohols cannot be absorbed and therefore bind a corresponding volume of water. Since body cells lack transport mechanisms for these substances (structure on p.175), they also cannot be absorbed through the intestinal epithelium and thus need to be given by intravenous infusion. The result of osmotic diuresis is a large volume of dilute urine, as in decompensated diabetes melli-tus. Osmotic diuretics are indicated in the prophylaxis of renal hypovolemic failure, the mobilization of brain edema, and the treatment of acute glaucoma attacks (p. 346). 

Osmotic diuretics. Diuretics that are filtered in the glomerulus but cannot be re-absorbed. An example is mannitol. Their presence leads to an increase in the osmolarity of the filtrate to maintain osmotic balance, water is retained in the urine. Glucose, like mannitol, can also behave as an osmotic diuretic. In diabetes mellitus, the concentration of glucose in the blood exceeds the maximum resorption capacity of the kidney glucose remains in the filtrate, leading to the osmotic retention of water in the urine. 

Some 65% of the filtered sodium is actively transported from the lumen of the proximal tubule by the sodium pump (Na", K -ATPase). Chloride is absorbed passively, accompan)dng the sodium bicarbonate is also absorbed, through the action of carbonic anhydrase. These solute shifts give rise to the iso-osmotic reabsorption of water, with the result that > 70% of the glomerular filtrate is returned to the blood from this section of the nephron. The epithelium of the proximal tubule is described as leaky because of its free permeability to water and a number of solutes. Osmotic diuretics such as mannitol are solutes which are not reabsorbed in the proximal tubule (site 1. Fig. 26.1) and therefore retain water in the tubular fluid. Their effect is to increase water rather than sodium loss, and this is reflected in their special use acutely to reduce intracranial or intraocular pressure and not states associated with sodium overload. 

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