A reverse phase high performance liquid chromatography (RP-HPLC) method for the simultaneous estimation of Sitagliptin phosphate and Metformin hydrochloride in marketed tablet formulations is developed. The determination was carried out on an XTerraC8 (4.6 × 100 mm, 3 µm) column using a mobile phase of pH-9 phosphate buffer solution: acetonitrile: methanol in the ratio of 35:45:20. The flow rate was 0.6 ml/min. The analyte was monitored using UV detector at 260 nm. The retention time for Sitagliptin phosphate was 3.056 mins and for Metformin hydrochloride 2.420 mins. Linearity of Sitagliptin and Metformin were found in the range of 50 ppm to 150 ppm. Percentage recoveries were obtained in the range of for Sitagliptin 99.5% and for Metformin 100.4%. The proposed method is precise, accurate, selective, robust, reproducible and rapid for the simultaneous estimation of Sitagliptin phosphate and Metformin hydrochloride in tablet dosage forms.

A sensitive, rapid and cost-effective method based on HPTLC with UV detection was developed for the quantitation of Glibenclamide (GLIBEN), Rosiglitazone maleate (ROSI) and Metformin hydrochloride (MET) from a combined dosage form. Pre-coated RP-18 F254s aluminum sheets were used as the stationary phase. Methanol–tetrahydrofuran–water–glacial acetic acid (16: 3.6: 4: 0.4, v/v) used as the mobile phase, along with chamber saturation of 10 min offered an optimum migration (Rf = 0.54, 0.62 and 0.80 for GLIBEN, ROSI and MET, respectively). TLC Scanner 3 was used for densitometric evaluation of the chromatograms. DigiStore 2 Documentation System with winCATS software version 1.4.10 was used for the quantitation and photodocumentation. The LOD for GLIBEN, ROSI and MET was found to be 80 ng, 80 ng and 48 ng, respectively. Moreover, the LOQ was 200 ng, 200 ng and 120 ng for GLIBEN, ROSI and MET, respectively. The method was linear for GLIBEN (r = 0.9991), ROSI (r = 0.9993) and MET (r = 0.9988) within the tested range (200–1000, 200–1000 and 120–600 ng/band, respectively). The method was found to be precise and accurate for all the three drugs. The method was applied for the analysis of Triglucored tablets, and it proved to be a reliable quality control tool for the routine analysis of GLIBEN, ROSI and MET in a combined dosage form.

Fosinopril diacid is an angiotensin converting enzyme inhibitor with efficient antihypertensive action. It is an active metabolic product formed in the body from hydrolysis of its prodrug Fosinopril. A sensitive, rapid method with high recovery for Fosinopril diacid from human plasma was developed. Solid‐phase extraction technique employing Waters Oasis SPE cartridges gave clean samples with very high recovery of 97%. The analyte along with its internal standard (Benazepril hydrochloride) were chromatographed on an XTerra RP8 column (4.6 × 50 mm, 5 μm) using methanol–ammonium acetate buffer (10 mm; 90:10, v/v) as the mobile phase. A triple quadrupole mass spectrometer equipped with electrospray ionization source operated in the negative ion mode was used for detection. Multiple reaction monitoring scan mode was used for monitoring the transitions from m/z 434.00 → 237.15 for Fosinopril diacid and m/z 423.10 → 174.00 for Benazepril hydrochloride. Beer–Lambert’s law was obeyed in the range of 0.50–1,500.00 ng/ml (r = 0.9993). The stability of the drugs in human plasma and in stock solution was proved by performing stability tests as per US Food and Drug Administration guidelines. The method was successfully applied for a bioequivalence study of Fosinopril diacid in 36 healthy, adult, male volunteers under fasting conditions.