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For type 2 diabetes treatment, combinations of drugs from the thiazolidinedione and sulfonylurea groups are now available in the same tablet or capsule. Therefore, a stability-indicating and validated HPLC method was developed for simultaneous determination of pioglitazone, rosiglitazone, and glipizide in combined dosage forms. The examined drugs were subjected to different conditions such as acid and base, temperature, and UV light, and degradation of pioglitazone and glipizide was observed under thermal and acidic stress. However, selectivity of the presented method for pioglitazone, rosiglitazone, and glipizide assay against their degradation products was confirmed. It was also demonstrated to be robust, resisting small deliberate changes in pH of the buffer, flow rate, and percentage of acetonitrile in the mobile phase. The presented method utilizes a LiChrospher RP18 column (125 x 4.0 mm), acetonitrile in phosphate buffer at pH 4.3 (40 + 60, v/v) as the mobile phase, and UV detection at 225 nm for pioglitazonel glipizide or 245 nm for rosiglitazone/glipizide. The method was validated with respect to linearity, precision, and accuracy. Finally, the elaborated procedure was applied for the QC of pioglitazone/glipizide and rosiglitazone/glipizide mixtures.

A new high-performance liquid chromatography method was developed and validated for the quantitation of gliclazide and repaglinide in pharmaceutical formulations. Determination was performed using a LiChroCART RP-18 column, a mobile phase containing acetonitrile-phosphate buffer (pH 2.1; 60 + 40, v/v), and ultraviolet (UV) detection at 225 nm. Repaglinide was used as an internal standard for gliclazide determination and gliclazide for repaglinide assay. The method was validated with respect to linearity, precision, robustness, ruggedness, accuracy, and specificity. The calibration graphs ranged from 0.015 to 0.09 mg/mL for gliclazide and 0.06 to 0.36 mg/mL for repaglinide. Intra- and interday relative standard deviation values for the standard solutions were 0.70 and 1.01% for gliclazide and 0.78 and 0.93% for repaglinide, respectively. Total recoveries of gliclazide and repaglinide from the laboratory-prepared mixtures were 99.82 +/- 0.58 and 101.50 +/- 0.46% for gliclazide and repaglinide, respectively [mean +/- standard deviation (SD)]. In forced degradation studies, the effect of acid, base, oxidation, UV light, and temperature on both drugs was also investigated. Finally, the method was applied for the quality control of commercial gliclazide and repaglinide tablets. Total recovery was 100.40 +/- 0.35 and 104.46 +/- 0.23% for gliclazide and repaglinide, respectively (mean +/- SD).

The thin-layer chromatographic behavior of new oral antidiabetic drugs, pioglitazone, rosiglitazone, and repaglinide has been investigated. For reversed-phase (RP) chromatography, chemically bonded cyanopropyl plates with mobile phases comprising 1,4-dioxane with phosphate buffers were used. The influence of the pH on the separation of the drugs was also examined. Then, a simple, rapid, and stability-indicating high performance thin-layer chromatographic method has been developed and validated for the quantitative determination of pioglitazone in tablets. Analysis was performed with 1,4-dioxane–phosphate buffer of pH 4.4 (5:5) as the mobile phase. Detection and quantification were performed by classical densitometry at the wavelength of maximum absorption of pioglitazone, 266 nm. A calibration plot was constructed in the range of 0.4–2.4 µg/10 µL and was linear with a good correlation coefficient (r = 0.9957). Precision was validated by replicate analyses of standard solutions, and accuracy by analysis of fortified samples. The precision of the proposed chromatographic method expressed as mean relative standard deviation (RSD) was 4.99% and 2.57%, respectively, for the lowest and the highest calibration levels. Recovery from the fortified samples ranged from 98.09% to 103.28%. The mean (±SD) recovery from tablets was 99.79% ± 1.57%. [ABSTRACT FROM AUTHOR]