A. Bergman and D. Ebel, “Absolute Bioavailability of Sitagliptin, an Oral Dipeptidyl Peptidase-4 Inhibitor in Healthy Volunteers,” Biopharmaceutics & Drug Disposition, Vol. 28, No. 6, 2007, pp. 315-322. doi:10.1002/bdd.560
 G. A. Herman and A. Bergman, “Pharmacokinetics and Pharmacodynamic—Effects of the Oral DPP-4 Inhibitor Sitagliptin in Middle-Aged Obese Subjects,” Journal of Clinical Pharmacology, Vol. 46, No. 8, 2006, pp. 876- 886. doi:10.1177/0091270006289850
 M. L. Christensen, B. Meibohm, E. V. Capparelli, P. Velasquez-Mieyer, G. A. Burghen and W. V. Tamborlane, “Single- and Multiple-Dose Pharmacokinetics of Pioglitazone in Adolescents with Type 2 Diabetes,” Journal of Clinical Pharmacology, Vol. 45, No. 10, 2005, pp. 1137-1144. doi:10.1177/0091270005279578
 Bala, S. and R. Prameela, “Development and Validation of Spectrophotometric Method for the Determination of DPP4 Inhibitor, Sitagliptin in Its Pharmaceutical Dosage Forms,” International Journal of Pharmacy and Pharmaceutical Sciences, Vol. 2, No. 4, 2007, pp. 138-142.
 R. S. Mehta and D. M. Patel, “UV and Visible Spectrophotometric Analysis of Pioglitazone Hydrochloride in Bulk and Tablets,” Indian Journal of Pharmaceutical Sciences, Vol. 67, No. 4, 2005, pp. 487-489.
 A. J. Meeta, S. S. Pandya and G. Vidyasagar, “A Simple and Sensitive HPTLC Method for Estimation of Pioglitazone in Bulk and Tablet Dosage Forms,” Asian Journal of Research in Chemistry, Vol. 2, No. 2, 2009, pp. 207-209.
 W. Zeng, D. G. Musson, A. L. Fisher, L.Chen, M. S.Schwartz, E. J. Woolf, and A. Q. Wang, “Determination of Sitagliptin in Human Urine and Hemodi-alysate Using Turbulent Flow Online Extraction and Tandem Mass Spectrometry,” Journal of Pharmaceutical and Biomedical Analysis, Vol. 46, No. 3, 2008, pp. 534-542.
 T. Rad-hakrishna, R. D. Sreenivas and G. Om Reddy, “Determination of Pioglitazone Hydrochloride in Bulk and Pharmaceutical Formulations by HPLC and MEKC Methods,” Journal of Pharmaceutical and Biomedical Analysis, Vol. 29, No. 4, 2002, pp. 593-607. doi:10.1016/S0731-7085(02)00036-5
 E. I. Ramzia, E. F. Ehab and A. M. Bassam, “Liquid Chromatographic Determina-tion of Sitagliptin Either Alone or in Ternary Mixture with Metformin and Sitagliptin Degradation Product,” Talanta, Vol. 85, No. 1, 2011, pp. 673-680. doi:10.1016/j.talanta.2011.04.051
 M. Shyamala, S. Mohideen, T. Satyanarayana, C. NarasimhaRaju, K. P. Suresh and K. Swetha, “Validated RP-HPLC for Simultaneous Estimation of Sitagliptin Phosphate and Metformin Hydrochloride in Tablet Dosage Form,” American Journal of PharmTech Research, Vol. 2, No. 1, 2011, pp. 93-101.
 K. Dipak and K. Rajendra, “Simultaneous Determination of Pioglitazone, Metformin and Glimepiride in Pharmaceutical Preparations Using HPTLC Method,” Journal of Planar Chromatography, Modern TLC, Vol. 24, No. 4, 2011, pp. 331-334.
 K. Ghazala, S. Dinesh, Y. P. Agrawal, S. Neetu, J. Avnish and A. K. Gupta, “Simulta-neous Estimation of Metformin and Sitagliptin in Tablet Dosage Form,” Asian Journal of Biochemical and Pharmaceutical Research, Vol. 2, No. 2, 2011, pp. 352-358.
 R. N. Xu, L. Fan, M. J. Rieser and T. A. El-Shourbagy, “Recent Advances in High-Throughput Quantitative Bioanalysis by LC-MS/MS,” Journal of Pharmaceutical and Biomedical Analysis, Vol. 44, No. 2, 2007, pp. 342-355. doi:10.1016/j.jpba.2007.02.006