pH-sensitive spectrophotometric control of nilutamide in an automatic micro-flow system

Abstract

The drug nilutamide belongs to the pharmacological group of antiandrogens, clinically used to prevent tumor development observed in the first phase of the administration of analogues of gonadotrophin-releasing hormone in patients with prostate cancer. Due to the high toxicity of this drug, the chemical control in pharmaceutical formulations is extremely important. The aim of this work was to develop an automatic procedure, based on flow analysis, for the quantification of the drug nilutamide that could constitute a simpler alternative for routine quality control in industry that is normally performed by a chromatographic method. A new, very simple and high-throughput methodology was developed based on the spectrophotometric monitoring of the drug at the wavelength of 438 nm in a solution of sodium hydroxide, the only reagent used in this method. It was verified through spectrophotometric studies that by varying the pH conditions, electronic transitions from bonding orbitals π to anti-bonding orbitals π* occur in the molecular structure of nilutamide. In this work, the potentialities of the pulsed flow in the multipumping methodology were exploited taking into account the high viscosity of the sodium hydroxide solutions that impaired the flow of reagents and the development of reaction was expedited through a stopped-flow approach. The developed flow system allowed us to perform 24 determinations per hour, and the limit of detection was 2.26 mg L⁻¹.