Co-encapsulation in Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as an Emerging Therapeutic Strategy

Combination therapy, which involves the simultaneous use of two or more drugs within the same formulation, aims to broaden therapeutic activity, reduce the risk of resistance, and achieve synergistic or additive effects. This approach has gained prominence across diverse clinical settings, offering benefits such as enhanced efficacy, reduced side effects, and improved treatment outcomes in complex or chronic diseases. Despite these advantages, combination therapy faces challenges that must be overcome to fully realize its potential. To address these limitations, researchers have increasingly focused on nanosystems, particularly solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), which are especially effective in improving the bioavailability of poorly water-soluble drugs. This review highlights the key advantages of co-encapsulation strategies in combination therapy, emphasizing the roles of SLN and NLC. Published studies have shown that co-encapsulation within these nanosystems enhances drug stability, bioavailability, therapeutic efficacy, and provides controlled release, positioning them as promising tools for effective drug delivery. Current challenges and future perspectives for the clinical translation of SLN and NLC in combination therapies are also discussed, as these nanosystems, given their many advantages, remain at the forefront of research into innovative therapeutic strategies. Nonetheless, further investigation is needed to explore their full potential, particularly their underutilized capacity to support combination therapy. Although their application in this context has been limited to date, the therapeutic promise of SLN and NLC co-encapsulation continues to drive ongoing research.