Mannitol
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Mannitol
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| Systematic (IUPAC) name | |
| Hexane-1,2,3,4,5,6-hexol | |
| Identifiers | |
| CAS number | 69-65-8 |
| ATC code | A06AD16 B05BC01 B05CX04 |
| PubChem | 453 |
| DrugBank | APRD01083 |
| Chemical data | |
| Formula | C6H14O6 |
| Mol. weight | 182.172 |
| Pharmacokinetic data | |
| Bioavailability | ~7% |
| Metabolism | Hepatic, negligible. |
| Half life | 100 minutes |
| Excretion | Renal: 90% |
| Therapeutic considerations | |
| Pregnancy cat. |
C: (USA) |
| Legal status |
? |
| Routes | Intravenous Oral |
Mannitol or hexan-1,2,3,4,5,6-hexol (C6H8(OH)6) is an osmotic diuretic agent and a weak renal vasodilator. It is a sorbitol isomer.
[edit] Chemical properties
Chemically, mannitol is an alcohol and a sugar, or a polyol; it is similar to xylitol or sorbitol. However, mannitol has a tendency to lose a hydrogen ion in aqueous solutions, which causes the solution to become acidic. For this, it is not uncommon to add a substance to adjust its pH, such as sodium bicarbonate.
[edit] Uses
Mannitol is used clinically to reduce acutely raised intracranial pressure, until more definitive treatment can be given, e.g. after head trauma, and to treat patients with oliguric renal failure. It is administered intravenously, and is filtered by the glomerulus of the kidney, but is incapable of being reabsorbed from the renal tubule resulting in decreased water and Na+ reabsorption via its osmotic effect. Consequently, mannitol increases water and Na+ excretion, thereby decreasing extracellular fluid volume.
Mannitol can also be used to open the blood-brain barrier by temporarily shrinking the tightly coupled endothelial cells that make up the barrier. This makes mannitol indispensable for delivering various drugs directly to the brain (e.g. in the treatment of Alzheimer's disease).
Mannitol is also used as a sweetener for people with diabetes. Since mannitol has a negative heat of solution, it is used as a sweetener in "breath-freshening" candies, the cooling effect adding to the fresh feel. In doses larger than 20g, mannitol acts as a laxative, and is sometimes sold as a laxative for children.
It is sometimes used as an adulterant or Cutting agent for heroin, methamphetamines or other illicit drugs. In popular culture, when it is used in this manner, it is often referred to as baby laxative. Many television shows and films depicting drug culture make such references to baby laxative when in fact they are referring to Mannitol.[citation needed]
Mannitol can also be used to temporarily encapsulate a sharp object (such as a helix on a lead for an artificial pacemaker) while it is passing through the venous system. Because it dissolves readily in blood, the sharp point will become exposed by the time it reaches its destination.
Mannitol may be admininstered in cases of severe Ciguatera poisoning. Severe ciguatoxin, or "tropical fish poisoning" can produce stroke-like symptoms.
Mannitol is a non-permeating molecule i.e. it cannot cross biological membranes.
Mannitol is commonly used in the circuit prime of a heart lung machine during cardiopulmonary bypass (CPB). The presence of mannitol preserves renal function during the times of low blood flow and pressure, whilst the patient is on bypass. The solution prevents the swelling of endothelial cells in the kidney, which may have otherwise reduced blood flow to this area and resulted in cell damage.
Chemical Abstract Registry Numbers for Mannitol are: 123897-58-5 69-65-8 75398-80-0 85085-15-0
