Simultaneous determination of pioglitazone and glimepiride in their pharmaceutical formulations

Abstract

Two sensitive and precise methods were developed and validated for the simultaneous determination of pioglitazone hydrochloride and glimepiride as the bulk drugs and in their pharmaceutical formulations. Among the techniques adopted were chromatography [coupled TLC-densitometry and HPLC].Method I : Densitometric separation of the drugs was performed on aluminum plates precoated with silica gel 60 F254 as the stationary phase and the solvent system consisted of chloroform: toluene: glacial acetic acid: ethanol [4.5:4.5:1:1, v/v/v/v]. Densitometric evaluation of the separated zones was performed at 228 nm and 268 nm. The two drugs were satisfactorily resolved with RF values 0.4and 0.65 for pioglitazone hydrochloride and glimepiride, respectively. The accuracy and reliability of the method was assessed by evaluation of linearity 3-15µg/spot for pioglitazone hydrochloride and 0.1-3 µg/spot for glimepiride, precision (intra-day RSD 1.178% and inter-day RSD 1.152 % for pioglitazone hydrochloride, and intra-day RSD 1.101 % and inter-day RSD 0.999 % for glimepiride), accuracy (99.94 ± 1.30 % for pioglitazone hydrochloride and 100.74 ±1.58 % for glimepiride) and specificity, in accordance with ICH guidelines. Method II: chromatographic separation using a 250 mm x 4.6 mm, i.d. C18Lichrosorb™ 10µm analytical column. The mobile phase consisted of phosphate buffer [pH: 4]: methanol: acetonitrile: triethylamine [40:20:40:0.1, v/v/v/v] The average retention times under the conditions described were 4 minutes for pioglitazone hydrochloride and 7.5 minutes for Glimepiride, accuracy and reliability of the method was assessed by evaluation of linearity 5-175 µg/mL for pioglitazone hydrochloride and 5-30µg/mL for Glimepiride, precision (intra-day RSD 0.295% and inter-day RSD 0.215 % for pioglitazone hydrochloride, and intra-day RSD 0.345 % and inter-day RSD 0.231 % for glimepiride), accuracy (99.80 ± 1.16 % for pioglitazone hydrochloride and 99.47 ±2.07 % for glimepiride) and specificity, in accordance with ICH guidelines.