The aim of this study was to fabricate and characterize a pharmaceutical emulgel co-loaded with naproxen/eugenol for transdermal delivery to improve the analgesic and anti-inflammatory effects and to eliminate GIT adverse reactions. Emulgel was prepared using a slow emulsification method and evaluated for physical appearance, thermodynamic stability, viscosity, pH, spreadability, extrudability, in-vitro drug release, drug content, ex-vivo permeation, drug retention studies and in-vivo studies. The emulgel exhibited good physical attributes, being thermodynamically stable with no phase separation, having excellent homogeneity, and pH 5.5 to 6.5. Slight changes in viscosity, spreadability and extrudability with respect to high temperature were observed (p > 0.05). The drug content was 96.69 ± 1.18% and 97.24 ± 1.27% for naproxen and eugenol, respectively. The maximum release of naproxen after 12 h was 85.14 ± 1.11%, whereas eugenol was 86.67 ± 1.23% from emulgel following anomalous non-Fickian mechanism. The maximum % permeation of naproxen across skin was 78.5 ± 1.30, whereas maximum % permeation of eugenol was 83.7 ± 1.33 after 12 h. The skin retention of eugenol and naproxen was 8.52 ± 0.22% and 6.98 ± 0.24%, respectively. The optimized emulgel inhibited the carrageenan induced paw edema. The pain reaction times of optimized emulgel and standard marketed product (Voltral®) were 11.16 ± 0.17 and 10.36 ± 0.47, respectively, with no statistically significant difference (p > 0.05). This study concluded that transdermal delivery of naproxen-eugenol emulgel synergized the anti-inflammatory and analgesic effects of naproxen and eugenol.
Keywords: eugenol; inflammation; naproxen; pain; skin permeation; sustainability of natural resources; transdermal emulgel.