Multi-Wavelength Spectrophotometric Analysis: Determination of Sitagliptin and Metformin in Tablets

Introduction

Diabetes Mellitus is an epidemic recognized by the World Health Organization (WHO) as a global threat. The organization estimates that there are currently more than 347 million people with diabetes in the world, and this number is likely to more than double by 2030. An estimated 1.5 million people died from diabetes in 2012. More than 80% of diabetes deaths are recorded in low- and middle-income countries, most of which are less prepared to face this epidemic; in our country this disease represents a high burden for the community. According to WHO projections, diabetes will be the seventh leading cause of mortality by 2030.

In Mexico, Diabetes Mellitus ranks first in number of deaths per year, with cardiovascular diseases being the main causes of this mortality (70 to 80%); mortality rates show an upward trend in both sexes with more than 70 thousand deaths and 400,000 new cases in 2010. Diabetes is a cardiovascular risk factor and is equivalent to having suffered a previous myocardial infarction.

Diabetes Mellitus is a non-curable, chronic, progressive, complex treatment condition that requires health professionals trained in the management of the disease, access to the necessary medications and supplies, education for living with diabetes, and the active and committed participation of the person with diabetes in the day-to-day management of their disease for the proper control of their condition.

Diabetes mellitus (DM) is a systemic, chronic degenerative disease of heterogeneous character, with variable degrees of hereditary predisposition and with the participation of various environmental factors, characterized by chronic hyperglycemia due to a deficiency in the production or action of insulin, which affects the intermediate metabolism of carbohydrates, proteins and fats. Sustained hyperglycemia over time is associated with damage, dysfunction and failure of various organs and systems, especially kidneys, eyes, nerves, heart and blood vessels.

Diabetes Mellitus is an untreatable, complex treatment condition that requires health professionals trained in the management of the disease, access to the necessary medicines and supplies, of education to live with diabetes and of active and committed participation of the person with diabetes in the day-to-day management of their disease for the proper control of their condition.

Combination drugs have proven to be effective in the control of metabolic syndrome and play an important role in pharmacological treatments. Biguanides such as metformin and DPP-4 (dipeptidyl peptidase 4 enzyme) inhibitors such as sitagliptin are used in the control of DM. The first drug of choice in the treatment of DM is metformin (Met). Currently, in cases that do not achieve the therapeutic objectives with Met in monotherapy, a combination with sitagliptin phosphate (Sgt) is suggested. These drugs are available in tablet form in different ratios of 1:10 (50:500 mg), 1:17 (50:850 mg) or 1:20 (50:1000) (Sgt:Met).

According to Lofty et al. (Lotfy, Mohamed, & Mowaka, 2015) Sgt is a relatively new drug, not yet official in any of the pharmacopoeias, but Met is official in the British Pharmacopoeia (BP) (BP, 2009), in the United State Pharmacopeia (USP) (USP, 2007) and in the United Mexican State Pharmacopeia (FEUM) (FEUM, 2011). Literature survey has revealed several methods for the estimation of Met and Sgt alone or in combination, or with glipizide, glimepiride and pioglitazone in pharmaceutical tablet formulations. The main problem of spectrophotometric analysis of binary mixtures is the simultaneous determination of the compounds in the same mixture without prior separation. Derivatized spectrophotometry, which is a useful means of resolving two overlapping spectra and eliminating matrix interferences in the assay of binary mixtures, can be used for the determination of the compounds in the same mixture without prior separation.

Spectrophotometric methods in the ultraviolet region to analyze multicomponent are based on the recording and mathematical processing of absorption spectra in which analytes are overlapping. Derivatization spectrophotometry, ratio spectrophotometry and other spectral calibration techniques offer the following advantages: they avoid prior separation techniques such as extraction, constituent concentration and clean-up steps that may be necessary for analysis; spectral data are easily acquired with low-cost equipment; the process is fast, accurate and simple; for quality control in routine and commercial pharmaceutical analysis.