Sodium Hyaluronate (CAS: 9067-32-7)

Basic Information

Sodium hyaluronate is the sodium salt of hyaluronic acid, a glycosaminoglycan 

found in various connective, epithelial, and neural tissues. Sodium hyaluronate,

a long-chain polymer containing repeating disaccharide units of Na-glucuronate-

N-acetylglucosamine, occurs naturally on the corneal endothelium, bound to

specific receptors for which it has a high affinity. The polyanionic form, commonly

referred to as hyaluronan, is a visco-elasticpolymer normally found in the aqueous

 and vitreous humour. 

Medical uses

Sodium hyaluronate is used as a viscosupplement, administered through a series of

injections into the knee, increasing the viscosity of the synovial fluid, which helps

lubricate, cushion and reduce pain in the joint. It is generally used as a last resort

before surgery and provides symptomatic relief, by recovering the viscoelasticity of

the articular fluid, and by stimulating new production from synovial fluid. Use of

sodium hyaluronate may reduce the need for joint replacement. Injections appear to

increase in effectiveness over the course of four weeks, reaching a peak at eight weeks

and retaining some effectiveness at six months, with greater benefit for osteoarthritis

than oral analgesics. It may also be effective when used with other joints.

Sodium hyaluronate may also be used in plastic surgery to reduce wrinkles on the face

or as a filler in other parts of the body. It may be used in ophthalmology to assist in the

extraction of cataracts, the implantation of intraocular lenses, corneal transplants, 

glaucoma filtration, retinal attachment and in the treatment of dry eyes.

Sodium hyaluronate is also used to coat the bladder lining in treating interstitial cystitis.

Contraindications

Sodium hyaluronate is contraindicated for people who are sensitive to hyaluronate

 preparations, or when there are infections or skin disease at the injection site.

Adverse effects

Adverse effects are relatively rare when used to treat the joints.

When used in ophthalmological procedures, sodium hyaluronate may cause postoperative 

inflammation, corneal edema or decompensation, and short-term increases in intraocular pressure.

Mechanism of action

Sodium hyaluronate functions as a tissue lubricant and is thought to play an important role in

modulating the interactions between adjacent tissues. Sodium hyaluronate is a polysaccharidewhich

is distributed widely in the extracellular matrix of connective tissue in man. It forms a viscoelastic

solution in water which makes it suitable for aqueous and vitreous humor inophthalmic surgery.

Mechanical protection for tissues (iris, retina) and cell layers (corneal, endothelium, and epithelium)

are provided by the high viscosity of the solution. Elasticity of the solution assists in absorbing

mechanical stress and providing a protective buffer for tissues. This viscoelasticity enables maintenance

of a deep chamber during surgical manipulation since the solution does not flow out of the open anterior

chamber. In facilitating wound healing, it is thought that it acts as a protective transport vehicle, taking

peptide growth factors and other structural proteins to a site of action. It is then enzymatically degraded

and active proteins are released to promote tissue repair. Sodium hyaluronate is being used intra-articularly

to treat osteoarthritis.

Physical and chemical properties

Sodium hyaluronate is an ophthalmic agent with viscoelastic properties that is used in 

joints to supplement synovial fluid.