Eletrooxidação de tadalafila em eletrodo de carbono vítreo e determinação direta em formulação farmacêutica por voltametria

Abstract

The pharmaceutical market has grown in recent years and many products have been target of adulteration. The present work reports the study of the Cialis ® which has been one target of forgery. This drug has as active substance the Tadalafil, derived from Sildenafil (Viagra) and Vardenafil (Levitra). The Tadalafil is a potent selective PDE5 inhibitor (phosphodiesterase type 5), and is widely used to treat erectile dysfunction and pulmonary arterial hypertension. In this work, was employing glassy carbon electrode as working electrode to evaluate the oxidation-reduction processes of tadalafil. Initially was executed kinetic studies to determine the charge transfer coefficient (α), the number of electrons (n) involved in the oxidation reaction, the diffusion coefficient (D) and heterogeneous electron transfer constant (K'). For quantify the Tadalafil was developed a new analytical methodology for pharmaceutical formulations (Cialis ®) using the techniques of differential pulse voltammetry and Square Wave, the limits of quantification obtained were 2.71x10-6 to 3.72 x10-7 mol.L-1, respectively. Studies were carried out with interferents present in the pharmaceutical formulation in the ratio 1:1 and 1:10. The electrochemical data were compared with liquid chromatography results, presenting a good correlation, indicating that the proposed electrochemical method can be used to control that pharmaceutical formulation.