ROLE OF SOLID LIPID NANOPARTICLES IN ENHANCING ORAL BIOAVAILABILITY OF POORLY SOLUBLE DRUGS: A COMPREHENSIVE REVIEW

Poor oral bioavailability remains one of the major challenges in drug development, particularly for poorly water-soluble drugs categorized under the Biopharmaceutical Classification System Classes II and IV. Solid lipid nanoparticles (SLNs) have emerged as a promising nanocarrier system capable of overcoming this limitation through multiple mechanisms. Composed of physiologically compatible lipids and stabilized by surfactants, SLNs offer unique advantages, including enhanced solubility, protection from enzymatic degradation, prolonged circulation time, and targeted delivery. This review provides a comprehensive overview of SLNs with a focus on their role in enhancing the oral bioavailability of lipophilic drugs. Various techniques, such as high-pressure homogenization, solvent evaporation, and microemulsion-based approaches, are discussed in terms of preparation efficiency and scalability. Mechanistically, SLNs improve bioavailability through increased surface area, mucosal adhesion, lymphatic uptake, and bypassing hepatic first-pass metabolism. Applications of SLNs span multiple therapeutic categories, including anticancer, antiviral, antidiabetic, and anti-inflammatory drugs, demonstrating significant improvements in pharmacokinetics and pharmacodynamics. Despite their potential, SLNs face challenges related to low drug loading, stability concerns, polymorphic transitions, and regulatory complexities. Current advances in surface modifications, hybrid systems, and stimuli-responsive SLNs offer promising future directions. Regulatory considerations and emerging clinical evidence also highlight the growing importance of SLNs in modern pharmaceutics. This review underscores the significance of SLNs as an innovative platform for enhancing the oral delivery of poorly soluble drugs, thereby offering new avenues for effective and patient-friendly therapeutic interventions.