The key difference between sodium hyaluronate and carboxymethylcellulose is that sodium hyaluronate shows excellent moisturizing and mucus-layer adhesive properties, whereas carboxymethylcellulose provides excellent bio-adhesive characteristics and it can also increase the tear-retention time.
Sodium hyaluronate and carboxymethylcellulose are important chemical substances in lubricating eye drops for dry eyes. These are valuable ingredients in eye drops.
CONTENTS
1. Overview and Key Difference
2. What is Sodium Hyaluronate
3. What is Carboxymethylcellulose
4. Sodium Hyaluronate vs Carboxymethylcellulose in Tabular Form
5. Summary – Sodium Hyaluronate vs Carboxymethylcellulose
What is Sodium Hyaluronate?
Sodium hyaluronate can be described as the sodium salt of hyaluronic acid. In other words, it is a glycosaminoglycan having a long-chain polymer of disaccharide units. These disaccharide units contain Na-glucuronate-N-acetylglucosamine. Furthermore, sodium hyaluronate can bind with specific receptors that have a high affinity for this compound. The polyanionic form of this compound is “hyaluronan.” It is a visco-elastic polymer. This compound is common in the extracellular matrix of mammalian connective, epithelial, and neural tissues.
Figure 01: The Chemical Structure of Sodium Hyaluronate
Furthermore, sodium hyaluronate occurs in the corneal endothelium. The major function of this compound is that it acts as a lubricant for tissues and modulates the interactions between adjacent tissues. When dissolved in water, it can form a visco-elastic solution. When injected into the body, sodium hyaluronate disappears within hours of injection. But there are residual effects on contacted cells. The side effects of this compound (when used as an injection) include postoperative inflammation and corneal edema.
What is Carboxymethylcellulose (Cellulose Gum)?
Carboxymethylcellulose is also known as cellulose gum. It is abbreviated as CMC. We can define it as a cellulose derivative having carboxymethyl groups that are bound to some hydroxyl groups of the glucopyranose monomers in the cellulose backbone. Typically, CMC is important in its sodium salt form. It is named sodium CMC. The trade name for this compound in the market is Tylose.
Figure 02: The Chemical Structure of CMC
In the preparation of CMC, we need to synthesize it by the alkali-catalyzed reaction of cellulose in the presence of chloroacetic acid. In this process, the polar carboxyl groups render the solubility of cellulose and chemical reactivity. After the completion of this first step, the resultant reaction mixture usually contains about 60% CMC and 40% sodium salts such as sodium chloride and sodium glycolate. We can describe this product mixture as technical CMC, which is useful in manufacturing detergents. Thereafter, we need another purification step to remove the salt compounds and purify the CMC compound. This pure CMC is useful in the food industry, pharmaceutical industry, and toothpaste manufacturing. Moreover, there is a semi-purified product as well, which is important in paper applications, including the restoration of archival documents.
There are many applications of CMC, including the food industry, where it has the E number E466 or E469 (the enzymatically hydrolyzed form), which is useful as a viscosity modifier and as a thickener. In addition, it is important in stabilizing emulsions in products such as ice cream. Furthermore, CMC is useful in the production of toothpaste, laxatives, diet pills, water-based paints, detergents, textile sizing, paper products, etc.
What is the Difference Between Sodium Hyaluronate and Carboxymethylcellulose?
Both sodium hyaluronate and CMC compounds are important ingredients in eye drops. The key difference between sodium hyaluronate and carboxymethylcellulose is that sodium hyaluronate shows excellent moisturizing and mucus-layer adhesive properties, whereas carboxymethylcellulose provides excellent bioadhesive characteristics and it can also increase the tear-retention time.
The below infographic presents the differences between sodium hyaluronate and carboxymethylcellulose in tabular form for side by side comparison.
Summary – Sodium Hyaluronate vs Carboxymethylcellulose
Sodium hyaluronate is the sodium salt of hyaluronic acid. Carboxymethylcellulose is also known as cellulose gum. Both these compounds are important ingredients in eye drops. The key difference between sodium hyaluronate and carboxymethylcellulose is that sodium hyaluronate shows excellent moisturizing and mucus-layer adhesive properties, whereas carboxymethylcellulose provides excellent bioadhesive characteristics and can increase the tear-retention time.
Reference:
1. Groß, Dorothea, et al. “Comparative Study of 0.1% Hyaluronic Acid versus 0.5% Carboxymethylcellulose in Patients with Dry Eye Associated with Moderate Keratitis or Keratoconjunctivitis.” Clinical Ophthalmology (Auckland, N.Z.), Dove Medical Press, 11 June 2018.
Image Courtesy:
1. “Sodium hyaluronate” By Ed (Edgar181) – Own work (Public Domain) via Commons Wikimedia
2. “Carboxymethyl cellulose” By Edgar181 – Own work (Public Domain) via Commons Wikimedia
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