Evaluation of ophthalmic suspensions using surface tension

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Ophthalmic suspensions require precise dosing and uniform particle distribution, especially for water-insoluble drugs.
• Sedimentation necessitates immediate re-dispersibility for effective therapeutic delivery.
• Selecting suitable water-soluble polymers as suspending agents is critical but challenging.

Purpose of the Study:

• To investigate the relationship between surface tension and re-dispersibility in ophthalmic suspensions.
• To determine the optimal concentration of hydroxypropylmethylcellulose (HPMC) for enhancing suspension properties.
• To establish surface tension measurement as a viable strategy for ophthalmic suspension formulation.

Main Methods:

• Investigated surface tension changes in fluorometholone and indomethacin suspensions with varying HPMC concentrations.
• Measured re-dispersion times and observed particle aggregation.
• Correlated surface tension values with HPMC concentration and suspension re-dispersibility.

Main Results:

• HPMC addition significantly reduced surface tension in both fluorometholone and indomethacin suspensions.
• Optimal HPMC concentrations (0.0001-0.01 w/v% for fluorometholone, 0.0005-0.005 w/v% for indomethacin) resulted in rapid re-dispersion (<4s and <17s, respectively) and no particle aggregation.
• A strong correlation was observed between decreased surface tension, optimal HPMC concentration, and good re-dispersibility.

Conclusions:

• Surface tension measurement is a reliable indicator for determining optimal HPMC concentrations in ophthalmic suspensions.
• This method facilitates the formulation of stable, easily re-dispersible ophthalmic suspensions.
• Utilizing surface tension analysis is a valuable strategy for developing effective suspending pharmaceutical products for ophthalmic applications.