[Effect of solution viscosity on polymer precorneal residence time evaluated by in vitro method]

Area of Science:

• Ophthalmology
• Materials Science
• Pharmaceutics

Background:

• Precorneal residence time is a critical factor for ocular drug efficacy.
• Water-soluble polymers are widely used in ophthalmic formulations to enhance drug delivery.
• Understanding polymer properties, such as viscosity, is essential for optimizing ocular retention.

Purpose of the Study:

• To investigate the impact of solution viscosity on the precorneal residence of five distinct water-soluble polymers.
• To determine the relationship between polymer properties, viscosity, and ocular surface adsorption.
• To identify polymers with optimal precorneal retentive capabilities.

Main Methods:

• Utilized the captive bubble technique to assess polymer desorption from ocular surfaces.
• Studied polymer residence in vitro on freshly enucleated rabbit eyes under physiological conditions.
• Measured changes in contact angle as an indicator of the desorption process.

Main Results:

• Carbopol and sodium hyaluronate (HA) demonstrated optimal precorneal retention, adsorbing to the ocular surface for over 15 minutes.
• Increasing solution viscosity from 12 mPa.s to 50 mPa.s prolonged the residence time of carbopol by 10 minutes and HA by 7 minutes.
• The residence time of sodium carboxymethylcellulose was unaffected by the increase in solution viscosity.

Conclusions:

• Higher solution viscosity is beneficial for improving the ocular residence time of bio-adhesive polymers.
• Viscosity plays a significant role in the precorneal retention of specific polymers, influencing their adsorption and desorption kinetics.
• These findings have implications for the formulation of ophthalmic drugs to enhance therapeutic outcomes.