Formulation and evaluation of tailored emulgels for enhanced topical cutaneous and ophthalmic delivery of antimicrobial and keratolytic agents.

BACKGROUND

Topical drug delivery systems are increasingly favored for their ability to bypass first-pass metabolism and minimize systemic adverse effects. Emulgels, which combine the therapeutic benefits of emulsions and gels, offer a stable and effective platform for the delivery of both lipophilic and hydrophilic antimicrobial agents. The present study was designed to develop and optimize a versatile dual-route emulgel platform, featuring distinct formulations tailored for topical cutaneous delivery (incorporating salicylic acid for keratolytic and anti-acne applications) and topical ophthalmic delivery (incorporating ciprofloxacin and chloramphenicol for ocular surface infections), utilizing advanced statistical modeling to achieve superior therapeutic performance.

METHODS

Emulgel formulations were prepared by integrating drug-loaded oil phases into aqueous gelling matrices, utilizing high-shear mixing to ensure homogeneity. Optimization of formulation variables, including polymer concentration and surfactant-to-co-surfactant ratios, was achieved using Response Surface Methodology (RSM) based on reduced polynomial models. The optimized formulations were evaluated for physical stability, rheological profile, globule size, and in vitro drug release kinetics across Cellophane® membranes.

RESULTS

Statistical modeling identified ideal concentrations (1.25% gelling agent and 1:2 surfactant ratio) that yielded stable, nanostructured systems with globule sizes in the range of 185 to 210 nm. The formulations exhibited pseudoplastic, shear-thinning behavior, ensuring ease of application and structural stability over the study duration. In vitro release studies demonstrated sustained drug release profiles, with optimized batches showing significant permeability enhancement (Kp) and steady-state flux (Jss) compared to conventional topical preparations (p < 0.05 for all). Accelerated stability results over 90 days showed that the emulgels maintained their initial pH (5.6-6.1) and a smooth, white appearance. Quantitative assessment utilized similarity factors (f1 and f2), where f1 < 15 and f2 > 50 confirmed profile similarity after storage. The safety profile of the optimized emulgels evaluated via skin and eye irritation tests had no signs of erythema, edema, or clinical discomfort were observed during the study period.

CONCLUSIONS

The study successfully developed stable, specialized emulgel formulations optimized for separate topical cutaneous and ophthalmic applications. The systematic integration of RSM enabled the precise formulation of delivery systems providing enhanced keratolytic, anti-acne, and anti-infective efficacy, supporting their potential application as robust alternatives to conventional vehicles in the management of localized dermal and ocular conditions.