Flocculation of suspensions containing nonionic surfactants by sorbitol

Area of Science:

• Pharmaceutical Sciences
• Colloid and Surface Chemistry

Background:

• Aqueous suspensions are common pharmaceutical formulations.
• Wetting agents and excipients like sorbitol significantly impact suspension stability.
• Understanding flocculation mechanisms is crucial for drug delivery.

Purpose of the Study:

• To investigate the flocculation behavior of drug suspensions containing sorbitol.
• To identify factors influencing the critical flocculation concentration (CFC) of sorbitol.
• To explore the relationship between cloud point and sorbitol-induced flocculation.

Main Methods:

• Preparation of aqueous suspensions with sulfamerazine, salicylamide, or butamben.
• Inclusion of polysorbate 20 or polysorbate 80 as wetting agents.
• Systematic variation of sorbitol concentration, temperature, and other excipients.

Main Results:

• High sorbitol concentrations induced flocculation via dehydration of surfactant polyoxyethylene groups.
• Cloud point correlated with sorbitol's critical flocculation concentration.
• Factors like temperature, surfactant type (polysorbate 20 vs. 80), and sodium sulfate addition affected sorbitol CFC.
• Drug type and methylparaben presence influenced cloud point and CFC.

Conclusions:

• Sorbitol-induced flocculation in suspensions is predictable and influenced by formulation components and conditions.
• Cloud point measurements can estimate the critical flocculation concentration of sorbitol.
• Careful selection of excipients and formulation parameters is essential for stable suspensions.