Formulation and in-vitro evaluation of oxaprozin transdermal patches for sustained anti-inflammatory therapy

Background: Inflammation is characterized by pain, altered membrane permeability, increased vascular activity, and protein denaturation. Oxaprozin, a BCS Class II NSAID, is often used to manage inflammation and pain but is limited by poor solubility and extensive first-pass metabolism, which reduces its effectiveness when administered orally. This study aimed to develop and evaluate oxaprozin-loaded transdermal patches as a patient-friendly alternative for sustained anti-inflammatory therapy. Methodology: Transdermal patches were formulated using the solvent-casting technique with hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP K-30) as film-forming polymers, along with plasticizers and permeation enhancers (propylene glycol and DMSO). A Box-Behnken design (13 runs) was employed to optimize the effects of polymer concentrations on adhesion strength and % cumulative drug release. The patches were characterized for thickness, folding endurance, surface pH, moisture content, drug content, and in vitro drug release. Result and Discussion: Pre-formulation studies confirmed drug-excipient compatibility and stability. P1 exhibited optimal performance with a thickness (0.123±0.34 mm), weight variation (94.5±0.56 %), drug content (94.47 %), folding endurance (25±0.1), and in vitro drug release (81.14±6.08 % over 24 hours). The release followed Korsmeyer-Peppas kinetics (R2 = 0.9677), indicating a diffusion-controlled release mechanism. Statistical analysis confirmed significant differences among formulations (p < 0.05) & stability studies showed no changes after 3 months. Conclusion: The optimized oxaprozin transdermal patches, particularly formulation P1, demonstrated uniformity, stability, and controlled drug release, establishing their potential as an effective alternative to oral NSAID therapy. Future in vivo studies are recommended to confirm therapeutic efficacy and clinical applicability.