Formulation and Evaluation of Orphenadrine Citrate as a Model Drug for Topical Hydrogel

Orphenadrine Citrate is a muscle relaxant, act as an anti- cholinergic drug and used in the treatment of Parkinson’s disease. The objective of this study was to design a topical hydrogel formulation using Orphenadrine Citrate as a model drug. The topical administration is an alternative route that can minimize the side effects and may improve patient drug delivery. Different formulas were prepared using different gelling agents with different concentrations, CMC (1, 2 and 3% w/w), Xanthan gum (0.5, 1 and 1.5% w/w) and HPMC K40 (2, 2.5 and 3% w/w). The prepared formulas were evaluated for physical appearance, pH, Spreadability, drug content, viscosity besides to in- vitro drug release. All the formulas prepared had acceptable hydrogel texture, increased viscosity as the gelling agent concentration increased, while spreadability decreased; in addition the pH hydrogel surface of the formulas showed within acceptable pH of skin. On the other hand, among the polymer hydrogel used, it was found that xanthan gum gave (98.3%) Orphenadrine citrate release within 90 minutes while other polymers CMC and HPMC K40 gel was 70% and 62.6% drug release respectively within 90 minutes. Finally, F6 was the optimum formula due to its acceptable hydrogel surface pH (6.7), good spreadability (4.4 cm2) and 98.3% Orphenadrine citrate release from the hydrogel.