Mannitol can be truly useful in the clinical setting as a diagnostic agent, osmotic diuretic and urinary irrigant. Mannitol’s chemical class is hexahydroxy alcohol and it is a pregnancy category B drug. Mannitol is a six-carbon sugar and is known by the generic name of mannitol or Osmitrol, which is the most common brand name. Mannitol is usually available in 5%, 10%, 15%, 20%, and 25% injection form. Mannitol is considered a diuretic which promotes urine production. It is also helpful in preventing the kidney from shutting down. It increases osmotic pressure of the glomerular filtrate, inhibiting reabsorption of water and electrolytes and creates an osmotic gradient in the glomerular filtrate and blood (Lippincott Williams & Wilkins, 2008, p.183).
Mannitol has its major effect in the proximal tubule and the descending limb of the loop of Henle. Water concentration is reabsorbed down the tubule, therefore the concentration of mannitol increases. “The concentration of tubular sodium is thereby reduced, creating a gradient for black-flux of reabsorbed sodium into the tubule, and a natriuresis (albeit of lower magnitude) accompanies the diuresis” (Ronco, Bellomo & Kellum, 2009, p. 552). Mannitol produces an excess of diuresis in natriuresis, and if there is an excessive water loss, there is a risk of hypernatremia and hyperkalemia. Mannitol is primarily used as prevention and treatment of the oliguric phase of renal failure. It also, reduces ICP (intracranial pressure) and IOP (intraocular pressure) and is often used as a treatment for cerebral edema. Mannitol encourages urinary voiding of toxic substances for example salicylates, bromides and lithium. It is also used as a diagnostic tool in measuring of GFR (glomerular filtration rate).
According to Merriam-Webster, pharmacokinetics is “the characteristic interaction of a drug and the body in terms of its absorption, distribution, metabolism, and excretion”. The pharmacokinetics of mannitol is the following: I.V. route, there is a 30-60 min onset with a one hour peak and duration of six to eight hours and through irrigant route, there is a rapid onset with a rapid peak and a short duration (Karch, 2014, p.721). Lippincott Williams & Wilkins (2008) describe the absorption to be administered though I.V. which will result in a rapid distribution that remains in the cell; it is vaguely metabolized and effortlessly filtered by the glomeruli. It is crucial to point that mannitol crosses the placenta and may enter into the breast milk in female patients. Mannitol is usually excreted primarily in urine.
As stated by Ronco, C., Bellomo, R., & Kellum, J. A. (2009), osmotic diuretics like mannitol are distributed rapidly withdrawing water from the intracellular space. As a result, headache, vomiting, and nausea are the most common side effects in patients. If mannitol is used in excess without appropriate water intake it can result in critical dehydration. As mannitol withdraws water from the...