Qualitative and quantitative analysis of metronidazole formulations using a low-cost near infrared transmission spectrophotometer and chemometric tools

Abstract

For effective drug quality control and detection of falsified and substandard medicines in developing countries, there is an urgent need to develop reliable, rapid, and inexpensive analytical methods. In this work, a methodology combining a low-cost near infrared transmission spectrophotometer with chemometrics and sample analysis in solution has been applied to develop qualitative and quantitative methods to analyze metronidazole in various formulations. To achieve this, calibration and validation solution samples of metronidazole at different concentrations were prepared. The qualitative method consisted of building a model based on a data driven soft independent modeling of class analogy using metronidazole samples at the concentration of 100 mg L⁻¹ as the target class. The built model allowed a satisfactory identification of metronidazole at the target concentration and a clear discrimination of the excipient mixture and metronidazole samples at other concentration levels and related active pharmaceutical ingredients used to mimic falsified and substandard drugs. The quantitative method was based on a partial least squares regression model allowing the quantification of metronidazole in the concentration range of 50–125 mg L⁻¹. The regression model was fully validated according to the accuracy profile methodology. Both qualitative and quantitative methods were successfully employed to analyze various metronidazole tablet samples collected in Burkina Faso. The obtained outcomes underline the feasibility of using these economically accessible portable spectrophotometers as a first line screening tool for drug quality control and detection of falsified and substandard drugs in developing countries.