Pharmacology: Pharmacodynamics: Mechanism of action:
Sodium hyaluronate binds to fibronectin and accelerates the adhesion and extension of epithelial cells. Sodium hyaluronate also has an excellent water-holding property because each sodium hyaluronate molecule can retain many H2
Acceleration of corneal wound healing (rabbits):
Topical application of 0.1 - 0.5% sodium hyaluronate ophthalmic solutions accelerate the wound healing of corneal epithelium in rabbits.
Acceleration of corneal epithelial extension (rabbits):
Sodium hyaluronate accelerates the extension of corneal epithelial cells in isolated strips of cultured rabbit cornea.
Water retentive property (in vitro):
Weight loss of agar plugs due to water evaporation was prevented concentration-dependently by placing drops of 0.1 - 1.0% sodium hyaluronate solutions atop the plugs.
The effectiveness rates of this product in clinical studies including double blind study conducted on patients with keratoconjunctival epithelial disorder resulting from sicca syndrome (dry eye), Sjogren's syndrome, contact lens wearing, etc. are summarized as follows. (See Table 1.)
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Pharmacokinetics: Serum concentration:
Serum concentrations of hyaluronic acid were determined before topical application as well as on treatment day 3, day 9 (the last day of dosing), and day 10 in 6 healthy adult male volunteers. To the unilateral eye of the subjects, 0.1% (day 1) and 0.5% (day 2-9) ophthalmic solutions of sodium hyaluronate were instilled at a dose of one drop 5 times daily (day 1-2) and one drop 13 times daily (day 3-9). All serum concentrations determined before, during, and after treatment were less than the limit of quantitation (10μg/ml).
Intraocular distribution (rabbits):
Following a single topical application of 50 μl of 0.1% 14
C-sodium hyaluronate ophthalmic solution in rabbits with a normal cornea, radioactivity was only detected in the outer ocular area. Especially, the radioactivity in the bulbar conjunctiva was high and it was detectable till at least 8 hours after application. In contrast, the radioactivity level in the cornea was low and it was only detectable for 30 minutes after application.
Following topical application of 50 μl of 0.1% 14
C-sodium hyaluronate ophthalmic solution in rabbits with corneal epithelium wound, high radioactivity was detected in the cornea and aqueous humor even at 1
hour after application.