title: A comparative study of smart spectrophotometric methods for simultaneous determination of sitagliptin phosphate and metformin hydrochloride in their binary mixture.
abstract: Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude modulation (IAM) methods. The first two methods were used for determination of STG, while MET was directly determined by measuring its absorbance at λmax 232 nm. However, (IAM) was used for the simultaneous determination of both drugs. Moreover, another three methods were developed based on derivative spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations. Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained results were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there was no significant difference between the proposed methods and the reported one regarding both accuracy and precision.
authors.affiliation: Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, Kasr-El Aini Street, 11562 Cairo, Egypt; Pharmaceutical Chemistry Department, Faculty of Pharmaceutical Sciences & Pharmaceutical Industries, Future University, 12311 Cairo, Egypt.
authors.forename: Hayam M
authors.initials: HM
authors.lastname: Lotfy
authors.affiliation: Analytical Chemistry Department, Faculty of Pharmacy, Helwan University, Ein Helwan, 11795 Cairo, Egypt; Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, October University for Modern Sciences and Arts, 11787 6 October City, Egypt.
authors.forename: Dalia
authors.initials: D
authors.lastname: Mohamed
authors.affiliation: Analytical Chemistry Department, Faculty of Pharmacy, Helwan University, Ein Helwan, 11795 Cairo, Egypt; Department of Analytical Chemistry, Faculty of Pharmacy, British University in Egypt, 11837 El-Sherouk City, Egypt. Electronic address: shereen.hassib@bue.edu.eg.
authors.forename: Shereen
authors.initials: S
authors.lastname: Mowaka
mesh_terms: D004338:Drug Combinations; D007004:Hypoglycemic Agents / Q000032:analysis*; D057230:Limit of Detection; D008687:Metformin / Q000032:analysis*; D000068900:Sitagliptin Phosphate / Q000032:analysis*; D013053:Spectrophotometry / Q000379:methods*; D013607:Tablets
chemical_list: D004338:Drug Combinations; D007004:Hypoglycemic Agents; D013607:Tablets; D008687:Metformin; D000068900:Sitagliptin Phosphate
keywords: Amplitude subtraction method; Induced amplitude modulation method; Metformin hydrochloride; Modified amplitude subtraction method; Sitagliptin phosphate