STABILITY INDICATING RP-HPLC METHOD FOR SIMULTANEOUS DETERMINATION OF METFORMIN HYDROCHLORIDE AND PIOGLITAZONE HYDROCHLORIDE IN DOSAGE FORM

Stability-indicating high performance liquid chromatographic (HPLC) method was developed for simultaneous analysis of metformin hydrochloride (MET) and pioglitazone hydrochloride (PIO) in dosage forms. Chromatographic separation was performed on C8 column (Qualisil BDS 250 mm × 4.6 mm, 5 μm) with a mixture of methanol and water at 45:55 (v/v) containing 0.2% (w/v) n-heptanesulfonic acid (HSA) and 0.2% (v/v) triethyl amine (TEA) as mobile phase. The flow rate was 1 mL/min and eluents were detected at 265 nm. The described method shows linearity between 100–750 μg/mL for MET and 5–30 μg/mL for PIO with respective correlation coefficient (r^2) values of 0.9996 and 0.9997. Drugs were subjected to acidic and basic hydrolysis, oxidative, photolytic, neutral and thermal degradations. This method revealed 14 degradation products and among these products D1, D3, D11, D12 and D14 were identified using impurity standards.