Effect of Polymorphism and Application of Kinetic Models for the Evaluation of In Vitro Dissolution Profiles of an Eletriptan Hydrobromide Formulation

The intent of this work was to study the effect of polymorphism on dissolution properties and to apply several methods to evaluate the dissolution profiles of immediate-release tablets containing alpha (α) and beta (β) forms of eletriptan hydrobromide (EH). The polymorphs were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The dissolution conditions were USP Apparatus 2 (paddle) with 900 mL of 0.1 N HCl medium at a rotation speed of 100 rpm. The dissolution profiles were compared using model-independent, model-dependent, and statistical methods. In the model-independent approaches, dissolution efficiency (DE), mean dissolution time (MDT), difference factor (f1), and similarity factor (f2) were evaluated. A statistical assessment of DE data was performed using ANOVA and the t-test. Dissolution kinetics was determined using model-dependent approaches in which nine drug release mathematical models were evaluated. The dissolution profile of the α formulation was best represented by the Weibull model, and the β formulation by the Korsmeyer–Peppas model. The calculated fit factors infer that the two tablet formulations are similar with minor differences. Statistical and model-dependent approaches demonstrate that there may be a difference in the drug release mechanism.