Electrochemical behaviour and determination of niraparib using glassy carbon and boron-doped diamond electrodes

Niraparib tosylate (NPB) is a polyadenosine diphosphate (ADP)-ribose polymerase (PARP) inhibitor and is used to treat ovarian cancer patients with BRCA1/2 loss-of-function mutations. The objective of this study was to provide a comprehensive analysis of the electrochemical behaviour of NPB and to develop sensitive and rapid electroanalytical methods for the quantification of NPB. These methods were developed employing a glassy carbon electrode (GCE) and a boron-doped diamond electrode (BDDE). The influence of the supporting electrolyte and pH on the peak potentials and currents of NPB was investigated through the use of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). At a concentration of 0.1 mM NPB, the highest voltammetric peak response was observed in 0.1 M H2SO4 using a GCE and 0.5 M H2SO4 using a BDDE. The bare BDDE exhibited a diffusion-controlled process, whereas the GCE demonstrated an adsorption-controlled process. Based on the results and the number of electrons transferred (similar to 2 electrons), it is hypothesised that the electrooxidation of NPB occurs either by oxidation of the piperidine moiety to 1-hydroxypiperidine (N-hydroxypiperidine) to give NPB-PIPERIDINOX or by oxidation of the 2H-indazole moiety to indazolone to give NPB-INDAZOLONE. Under optimal experimental conditions, calibration curves for NPB were obtained at 0.8-10 mu M, with a limit of detection (LOD) of 0.016 mu M, using the GCE with adsorptive stripping differential pulse voltammetry (AdSDPV), and 10-100 mu M with an LOD of 0.285 mu M using BDDE with DPV. A recovery study was conducted on a commercially available serum sample using the standard addition method for both electrodes. The results demonstrated excellent recoveries (98.93-102.85 %) and reproducibility, with a relative standard deviation (RSD) of <2.0 % (N = 5).