Taguchi Approach for Optimization of a Green Quantitative 1H-NMR Practice for Characterization of Levetiracetam and Brivaracetam in Pharmaceuticals.

Background: Recently, quantitative nuclear magnetic resonance (qNMR) competes with separation techniques such as high performance liquid chromatography (HPLC) and capillary electrophoresis for quantification purposes when dealing with molecules that lack a chromophore.

Objective: The advantages of the proton nuclear magnetic resonance spectroscopy as a revolutionary quantitative analysis method were exploited aimed at simple and green assessment of two racetams, namely levetiracetam (LEV) and brivaracetam (BRV), as a new family of antiepileptic medications with a unique mechanism of action. The developed technique was effectively used to determine LEV in Keppra tablets and BRV in laboratory-prepared tablets without interfering with the ordinarily suspected excipients.

Method: A Taguchi approach was applied as a powerful and user-friendly statistical technique for optimization of the qH1NMR experimental design for both drugs. The optimum acquisition conditions were number of scans 32, pulse angle 20°, and relaxation delay of 40 s for LEV and number of scans 128, pulse angle 90°, and relaxation delay of 1 s for BRV. NMR spectra were obtained by means of phloroglucinol as an internal standard and dimethyl sulfoxide-d6 as a solvent.

Results: The diagnostic doublet of doublet quantitative signals at 4.3 and at 4.2 ppm were chosen to estimate LEV and BRV, respectively. The recovery of both drugs was quantified through the range of 0.1-12 mg/mL. The limits of detection were 0.013, 0.0013 and the limits of quantitation were 0.04, 0.0039 mg/mL for LEV and BRV correspondingly.

Conclusions: The suggested technique was fully validated according to ICH guidelines and proved to be an eco-friendly practice by means of three different assessment tools, including the green analytical procedures index, national environmental methods index, and analytical eco-scale. qH1NMR should be considered a green alternative for quantification and quality control assessment of pharmaceuticals.

Highlights: This research represents the first simple, quick, and green alternative method for determination of both racetams in their pharmaceuticals.