Desenvolvimento de uma formulação semissólida contendo diclofenaco de sódio e a validação preliminar de sua metodologia de análise

Abstract

Diclofenac sodium is a non-steroidal anti-inflammatory drug widely used in the treatment of inflammatory and painful conditions. The topical application is an effective and safe alternative, since it reduces the systemic adverse effects. This study aimed to develop and characterize a semisolid gel formulation containing 1% (w/w) diclofenac sodium, as well as to validate, preliminarily, a UV spectrophotometric method for its quality control. The formulation was subjected to physicochemical tests (pH and density), centrifugation stability, and rheological analysis. During preliminary validation, the parameters of selectivity, linearity, precision, accuracy, and detection and quantification limits were evaluated in accordance with Anvisa RDC No. 166/2017. The gel presented a skin-compatible pH (6,17), density of 1.03 g/cm3, adequate physical stability in relation to the active ingredient and Herschel-Bulkley fluid behavior (pseudoplastic profile with yield point) and thixotropic behavior favorable for topical application. The UV spectrophotometric method for quality control of diclofenac sodium in semi-solid formulations proved to be selective, linear in the range of 5.0 to 25.0 μg/mL (R2=0.994), precise (RSD ≤ 5%), and accurate, with average recovery values ranging from 98.1% to 103.1%. The detection and quantification limits were 1.09 μg/mL and 3.31 μg/mL, respectively, and the diclofenac sodium content in the gel was 98.5%, within the acceptable range (90–110%). Thus, the developed formulation presented satisfactory quality, and the validated analytical method proved to be simple, low-cost, and suitable for routine analyses, ensuring the reliability of quality control of topical diclofenac sodium formulations.