In vitro microbicidal activity of W/O/W multiple emulsion for vaginal administration

Area of Science:

• Pharmaceutical Sciences
• Microbiology
• Materials Science

Background:

• Multiple emulsions are complex delivery systems with potential for topical and mucosal applications.
• Vaginal drug delivery requires formulations that ensure stability and controlled release of active pharmaceutical ingredients.
• Antimicrobial agents are essential for treating or preventing vaginal infections caused by bacteria and fungi.

Purpose of the Study:

• To evaluate the microbicidal activity of a W/O/W multiple emulsion designed for vaginal application.
• To investigate the influence of formulation components, including lactic acid, octadecylamine (ODA), and benzalkonium chloride (CBZ), on antimicrobial efficacy.
• To determine the impact of agitation methods on the reliability of microbicidal activity testing.

Main Methods:

• Formulation of a W/O/W multiple emulsion containing lactic acid, ODA, and CBZ.
• Assessment of microbicidal activity against Escherichia coli, Staphylococcus aureus, and Candida albicans.
• Comparative analysis of microbial inactivation under different agitation conditions.

Main Results:

• Microbicidal activity varied significantly based on the agitation procedure employed during testing.
• Interpretable and consistent results were achieved with gentle agitation post-microbial suspension introduction.
• Vigorous agitation led to unpredictable entrapment of ODA and CBZ within ethylene and propylene oxide copolymer (COE) micelles, affecting their availability.

Conclusions:

• The microbicidal efficacy of the W/O/W vaginal emulsion is highly dependent on the testing methodology.
• Gentle agitation is recommended for accurate assessment of the antimicrobial properties of this formulation.
• Formulation stability and the bioavailability of active agents (ODA, CBZ) are influenced by mechanical stress during testing.