Microspheres-in-Gel Systems for Transungual Drug Delivery: Current Advances and Future Perspectives. Its Structure 1. Introduction Onychomycosis overview Need for better delivery 2. Nail Barrier & Drug Penetration Keratin structure Challenges 3. Conventional Formulations Limitations 4. Advanced Delivery Systems Microspheres Nanoparticles Others 5. Microspheres-in-Gel Systems Mechanism Advantages 6. Polymers & Methods Ethyl cellulose, PLGA O/W method 7. Evaluation Techniques Release studies Antifungal studies 8. Research Gaps & Future Scope