A Review on Design of Nanoemulgel-Based Transdermal Drug Delivery Systems in Pharmaceuticals: Current Challenges and Future Prospects

Newly synthesized pharmaceuticals and some active phytoconstituents often possess a highly lipophilic nature, which presents challenges such as poor solubility, low oral bioavailability, and others. Emulsions provide a promising solution for incorporating both hydrophilic and lipophilic compounds. As well, the addition of thixotropic agents or colloidal polymers imparts the necessary viscosity to these preparations. This nanoemulgel approach introduces a novel transdermal drug delivery system that improves the therapeutic efficacy of BCS Class II and IV drugs. Therefore, this review provides a comprehensive overview of the latest research in transdermal nanoemulgel delivery. This review also includes a meta-analysis of studies demonstrating the superiority of nanoemulgel formulations over conventional products. In brief, the primary aim of nanoemulgels, which integrate multiple systems, is to overcome the limitations associated with individual components. While drugs are often limited by their physicochemical properties, emulsions can suffer from stability issues and reduced skin retention, whereas gels may have insufficient drug-loading capacity. Nanoemulgel formulations address these challenges by incorporating nanoemulsions into gels, thereby enhancing stability, prolonging skin contact time, and enabling rapid and controlled drug release. Nanoemulgels excel in targeted drug delivery due to their ease of application, avoidance of first-pass metabolism and gastrointestinal degradation, favorable safety profile, and stability. In conclusion, these advantages have led to growing interest in nanoemulgels as a promising transdermal drug delivery system.