Development and Optimization of Local Anesthetic Lidocaine Transdermal Films Using Solvent Casting Technique

Abstract

The present study was aimed at the development and characterization of polymeric transdermal patches of lidocaine for sustained drug delivery to provide prolonged therapeutic action, improve patient compliance, and reduce the frequency of drug administration. Lidocaine-loaded transdermal patches were prepared by the solvent casting method using Hydroxypropyl Methylcellulose (HPMC) and Sodium Alginate as film-forming polymers. Polyethylene glycol (PEG) was incorporated as a plasticizer, while D-limonene was used as a permeation enhancer. Eight formulations (F1–F8) were developed by varying the polymer concentration to optimize the formulation characteristics. The prepared patches were evaluated for physicochemical parameters including weight variation, thickness, folding endurance, drug content, percentage moisture loss, and percentage moisture absorption. The patches exhibited satisfactory physical appearance, uniform thickness, good flexibility, and acceptable mechanical strength. Drug content ranged from 79.53% to 93.56%, with formulation F8 showing the highest drug content (93.56%). In vitro drug release studies carried out using a Franz diffusion cell demonstrated sustained drug release over a period of 12 hours. Among all formulations, F4 exhibited the highest cumulative drug release (98.88%), while the optimized formulation F8 achieved 98.35% cumulative drug release with superior overall physicochemical characteristics. Drug release kinetic analysis of formulation F8 showed the best fit to the Higuchi model (R² = 0.973), indicating diffusion-controlled drug release through the hydrated polymeric matrix. Accelerated stability studies of the optimized formulation were conducted at 40 ± 2°C and 75 ± 5% relative humidity for three months. The formulation remained stable, showing only negligible changes in drug content, folding endurance, physical appearance, and cumulative drug release, confirming its satisfactory physical and chemical stability. The findings of the present investigation demonstrate that the developed polymeric transdermal patches are capable of delivering lidocaine in a sustained and controlled manner. The optimized formulation exhibited excellent physicochemical properties, prolonged drug release, and good stability, indicating its potential as an effective transdermal drug delivery system for long-term pain management. Further ex vivo and in vivo studies are recommended to establish its clinical efficacy and therapeutic performance.