Sodium croscarmellose is an internally
cross-linked sodium
carboxymethylcellulose for use as a
superdisintegrant in pharmaceutical formulations.
E468 is the
E number
E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...
of crosslinked sodium carboxymethyl cellulose, used in food as an
emulsifier
An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Althoug ...
.
Background
The cross-linking reduces water
solubility
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution.
The extent of the solubi ...
while still allowing the material to swell (like a
sponge
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throu ...
) and absorb many times its weight in water. As a result, it provides superior drug
dissolution and disintegration characteristics, thus improving formulas′ subsequent
bioavailability by bringing the active ingredients into better contact with bodily fluids.
Sodium croscarmellose also resolves formulators′ concerns over long-term functional stability, reduced effectiveness at high tablet hardness levels, and similar problems associated with other products developed to enhance drug dissolution. It is a very commonly used
pharmaceutical additive approved by the
U.S. Food and Drug Administration. Its purpose in most tablets – including dietary supplements – is to assist the tablet in disintegrating in the gastrointestinal tract promptly. If a tablet disintegrating agent is not included, the tablet could disintegrate too slowly, in the wrong part of the intestine or not at all, thereby reducing the efficacy and
bioavailability of the active ingredients.
Croscarmellose is made by first soaking crude
cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
in
sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and al ...
, and then reacting the cellulose with
sodium monochloroacetate to form sodium
carboxymethylcellulose. Excess sodium monochloroacetate slowly hydrolyzes to
glycolic acid
Glycolic acid (or hydroxyacetic acid; chemical formula HOCH2CO2H) is a colorless, odorless and hygroscopic crystalline solid, highly soluble in water. It is used in various skin-care products. Glycolic acid is widespread in nature. A glycolate (s ...
and the glycolic acid catalyzes the cross-linkage to form sodium croscarmellose.
[
]
Chemically, it is the sodium salt of a cross-linked, partly O-(carboxymethylated) cellulose.
Sodium croscarmellose was first used as a
stabilizer in horse supplements.{{Citation needed, date=February 2009
References
Excipients
Organic sodium salts
Cellulose
E-number additives