Spectrophotometric and HPLC determinations of anti-diabetic drugs, rosiglitazone maleate and metformin hydrochloride, in pure form and in pharmaceutical preparations

In this study, three spectrophotometric methods and one HPLC method were developed for analysis of anti-diabetic drugs in tablets. The two spectrophotometric methods were based on the reaction of rosiglitazone (RSG) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and bromocresol green (BCG). Linear relationship between the absorbance at λmax and the drug concentration was found to be in the ranges 6.0–50.0 and 1.5–12 μg ml−1 for DDQ and BCG methods, respectively. The third spectrophotometric method consists of a zero-crossing first-derivative spectrophotometric method for simultaneous analysis of RSG and metformin (MTF) in tablets. The calibration curves were linear within the concentration ranges of 5.0–50 μg ml−1 for RSG and 1.0–10.0 μg ml−1 for MTF. The fourth method is a rapid stability-indicating HPLC method developed for the determination of RSG. A linear response was observed within the concentration range of 0.25–2.5 μg ml−1. The proposed methods have been successfully applied to the tablet analysis.

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