Simultaneous Determination of Metformin and Pioglitazone in Presence of Metformin Impurity by Different Spectrophotometric and TLC – Densitometric Methods

New simple accurate methods were developed and validated for simultaneous determination of Metformin hydrochloride and Pioglitazone hydrochloride in presence of Metformin impurity Melamine , both in bulk powder and in pharmaceutical preparation using spectrophotometric methods and thin layer chromatography . Method A used zero order spectrophotometric technique for determination of Pioglitazone at 268nm and isoabsorbtive point spectrophotometric technique to determine Metformine at 255 nm in presence of the other drugs and used double divisor technique to determine Metformine in presence of the other drugs at 254 nm. Method B uses TLC densitometric technique for separation and simultaneous determination of the three drugs using toluene / methanol / acetic acid (5:5:0.5) as a developing system and 240nm as a scanning wavelength. This method were validated and shown to demonstrate good accuracy and precision according to ICH guidelines.