Development and evaluation of reservoir transdermal polymeric patches for controlled delivery of diclofenac sodium

The purpose of the study was to prepare a reservoir-controlled transdermal drug delivery patches containing a diclofenac sodium (DS) as a model drug to achieve a controlled release transdermal drug delivery system. DS-loaded patches were prepared by solvent casting technique using polyvinyl alcohol (5%) as backing membrane, drug, HPMC K100, propylene glycol (3%), and permeation enhancers (oleic acid, DMSO, and Tween 80) were employed in drug reservoir layer. Eudragit RS100 was used to prepare a rate-controlled membrane, which was casting over the drug reservoir layer. Formulated patches were evaluated for physicochemical properties, organoleptic characters, weight variation, thickness, flatness, folding endurance, tensile strength, swelling index, percentage erosion, moisture content uptake, water vapor transmission rate, content uniformity, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and skin irritation test. In vitro dissolution and ex vivo permeation studies were evaluated in phosphate buffer saline (pH 7.4). A skin irritation test confirmed that no allergic reaction or erythema was detected on rat skin after application for 24 h. The effect of permeation enhancers was elucidated on artificial human skin on Franz diffusion cell. Formulation F7 (DMSO) was optimized to achieve controlled drug release (92.14%) and high flux value (567.49 µg/cm 2 h). Optimized formulation (F7) follows zero-order kinetics (0.9753) with non-Fickian diffusion (0.949). The curve shape of formulations (F1–F8) was sigmoidal with turning, while F9 and F10 show steeper shape.