Composition of Mannitol
Mannitol is chemically designated as D-mannitol (C₆H₁₄O₆), a six-carbon polyol (sugar alcohol) that is a hydrogenated monosaccharide. 1
Chemical Structure and Classification
Mannitol is a linear six-carbon sugar alcohol with the molecular formula C₆H₁₄O₆, appearing as a white crystalline powder or free-flowing granules that is freely soluble in water 1
As a polyol, mannitol is classified as a hydrogenated monosaccharide, distinguishing it from other sugar alcohols like sorbitol, xylitol (also hydrogenated monosaccharides), or disaccharide-derived polyols like isomalt and maltitol 2
Mannitol is a fructose-derived compound, produced through the reduction of fructose 3, 4
Physical and Chemical Properties
The compound exists as a naturally occurring six-carbon sugar alcohol that is among the most abundant biochemical compounds in the biosphere, found widely in bacteria, yeasts, fungi, and plants 5, 3
Mannitol has a caloric content of 1.6 kcal/g, which is lower than most other sugar alcohols like sorbitol (2.6 kcal/g) or maltitol (3.0 kcal/g) 2
Pharmaceutical Formulation
When formulated for intravenous use, Mannitol Injection USP is a sterile, nonpyrogenic solution available in concentrations such as 25% in water for injection 1
The injectable solution contains no bacteriostat, antimicrobial agent, or added buffer (except for pH adjustment with sodium bicarbonate and/or hydrochloric acid), with a pH range of 4.5 to 7.0 1
The solution provides 1372 mOsm/L osmolarity when formulated at 25% concentration 1
Important Clinical Context
Mannitol functions as an osmotically active polyalcohol that is not normally detected in human plasma to any significant extent, making it useful as a laboratory marker when administered therapeutically 6
The FDA has designated mannitol as a food additive permitted in food or in contact with food on an interim basis pending additional study, with labeling requirements stating "excess consumption may have a laxative effect" for foods whose consumption may result in daily ingestion of 20 g or more 2