Chemical Properties
Hyaluronic acid is a white amorphous solid that is odorless and hygroscopic. It is soluble in water but insoluble in organic solvents. The specific rotation of its aqueous solution is -70°-80°. Its most prominent characteristic is its high viscosity. The viscosity of its solution can decrease irreversibly under the following conditions: pH value is lower or higher than 7; the presence of hyaluronidase; the presence of many reducing substances such as cysteine, pyrogallic acid, ascorbic acid or heavy metal ions; (4) ultraviolet light, electron beam irradiation, etc. A high molecular weight polymer composed of repeating disaccharide units of (1→3)-2-acetylamino-2-deoxy-β-D-glucose-(1→4)-O-β-D-glucuronic acid. When hydrolyzed, it produces a hexosamine (such as glucosamine) and a uronic acid (such as glucuronic acid). Originally used only as a biochemical reagent, it has now become a biochemical drug with high clinical value. Hyaluronic acid is found in a wide range of animal tissues in nature, including connective tissue, umbilical cord, skin, human serum, rooster comb, synovial fluid, brain, cartilage, vitreous humor, human urine, chicken embryos, rabbit eggs, and arterial and venous walls. Hyaluronic acid is often associated with proteins and coexists with other mucopolysaccharides. It exists in dissolved form in vitreous humor and synovial fluid, and in gel form in rooster comb and umbilical cord.
Veterinary Drugs and Treatments
Hyaluronic acid( 9004-61-9) is a natural complex sugar of the glycosaminoglycan
family and is a long-chain polymer containing repeating disaccharide
units of Na-glucuronate-N-acetylglucosamine. Hyaluronic
acid is indicated for use as a surgical aid in cataract extraction
(intra-and extracapsular), IOL implantation, corneal transplant,
glaucoma filtration and retinal attachment surgery. In surgical
procedures in the anterior segment of the eye, instillation of hyaluronic
acid serves to maintain a deep anterior chamber within
corneal endothelium and other surrounding tissues. Furthermore,
its viscoelasticity helps to push back the vitreous face and prevent
formation of a postoperative flat chamber. In posterior segment
surgery hyaluronic acid serves as a surgical aid to gently separate,
maneuver and hold tissues. Hyaluronic acid creates a clear field of
vision thereby facilitating intra- and post-operative inspection of
the retina and photocoagulation.
