Clinical audit of patients using DPP4 inhibitors in longstanding type 2 diabetes

Novel Approaches in the Management of Type 2 Diabetes and Associated Vascular Complications

Diabetes mellitus (DM) is growing in pandemic proportion and affects the affluent and developing nations equally. India has the dubious distinction of being known as the diabetes capital of the world. Epidemiological studies have shown that DM is under diagnosed and inadequately treated in our country. Insulin resistance and β-cell dysfunction are the two key pathophysiological determinants of the DM. The disease has metamorphosed during the last couple of decades with a significant change in the clinical presentation. Simultaneously, the therapeutic options for the management of DM have also increased in the last decade. This article highlights the research conducted by us over the last decade in the areas of pathogenesis, management, and complications of DM.

Mean centering-triple divisor and ratio derivative-zero crossing for simultaneous determination of some diabetes drugs in their quaternary mixture with severely overlapping spectra

Two ratio derivative spectrophotometric methods were performed for the simultaneous analysis of metformin hydrochloride, empagliflozine, linagliptin, and pioglitazone hydrochloride in their synthetic mixtures without prior chemical separation. The drugs are approved for the treatment of type 2 diabetes. Despite the various advances in the management of diabetes, it remains to be the major cause of disability and morbidity, including blindness, amputation, heart disease, peripheral neuropathy, and kidney disease. These techniques consisted of several steps using ratio and derivative spectra. The absorption spectra of the mentioned drugs were recorded in the range of 200-350 nm, which have the concentration ranges of 1.0-10, 2.5-30, 5.0-40, and 2.5-30 μg mL^-1 for metformin hydrochloride, empagliflozine, linagliptin, and pioglitazone hydrochloride, respectively, using zero-order spectra. The mean centring of ratio spectra combined with triple divisor were measured at the amplitude values 242, 256, 272 and 296 nm for metformin hydrochloride, empagliflozine, linagliptin and pioglitazone hydrochloride, respectively; the derivative ratio spectra-zero crossing quantifies the amplitude value of the analytical signal at 234, 244, 260 and 280 nm for metformin hydrochloride, empagliflozine, linagliptin and pioglitazone hydrochloride, respectively. The method was validated according to the ICH guidelines, accuracy, precision and repeatability were found to be within the acceptable limits. Finally, statistical comparisons between the proposed methods and with the reported methods with respect to accuracy and precision show that no significant difference was found by using Student's t-test, the F-test and one-way ANOVA.

The dipeptidyl peptidase-4 inhibitory effect of flavonoids is hindered in protein rich environments

Dipeptidyl peptidase-4 (DPP-4) inhibitors present a unique approach for the management of type 2 diabetes (T2D). In the present study, the inhibition of DPP-4 was evaluated for a large panel of flavonoids, important components of the human diet, using in vitro and ex vivo models. The activity of the isolated enzyme was assayed in vitro. Subsequently, the most active flavonoids were tested ex vivo in human whole blood and plasma. In this study, contrary to the in vitro fluorometric tests, flavonoids did not show inhibitory activity against DPP-4. Due to the discrepancy in the results between the in vitro and ex vivo approaches, plasma protein binding values were determined, presenting values from 43.9 to 100.0%. This work provides a new insight into the inhibitory activity for DPP-4, based on the flavonoid scaffold. Additionally, the obtained results showed that the inhibitory effect of flavonoids against DPP-4 was hindered in protein rich environments, like that occurring in blood, and indicated the need for experimental refinement in drug discovery for blood targets.

Dipeptidyl peptidase-4 and kidney fibrosis in diabetes

Diabetic nephropathy (DN) is the most common cause of end-stage kidney disease worldwide and is associated with increased morbidity and mortality in patients with both type 1 and type 2 diabetes. Recent evidence revealed that dipeptidyl peptidase-4 (DPP-4) inhibitors may exhibit a protective effect against DN. In fact, the kidney is the organ where the DPP-4 activity is the highest level per organ weight. A preclinical analysis revealed that DPP-4 inhibitors also ameliorated kidney fibrosis. In this review, we analyzed recent reports in this field and explore the renoprotective effects and possible mechanism of the DPP-4 inhibitors.

Analytical tools for determination of new oral antidiabetic drugs, glitazones, gliptins, gliflozins and glinides, in bulk materials, pharmaceuticals and biological samples

The review presents analytical methods for determination of new oral drugs for the treatment of type 2 diabetes mellitus (T2DM), focusing on peroxisome proliferator-activated receptor gamma agonists (glitazones), dipeptidyl peptidase 4 inhibitors (gliptins) and sodium/glucose co-transporter 2 inhibitors (gliflozins). Drugs derived from prandial glucose regulators, such as glinides, are considered because they are present in some new therapeutic options. The review presents analytical procedures suitable for determination of the drugs in bulk substances, such as pharmaceuticals and biological samples, including HPLC-UV, HPLC/LC-MS, TLC/HPTLC, CE/CE-MS, spectrophotometric (UV/VIS), spectrofluorimetric and electrochemical methods, taken from the literature over the past ten years (2006-2016). Some new procedures for extraction, separation and detection of the drugs, including solid phase extraction with molecularly imprinted polymers (SPE-MIP), liquid phase microextraction using porous hollow fibers (HP-LPME), HILIC chromatography, micellar mobile phases, ion mobility spectrometry (IMS) and isotopically labeled internal standards, are discussed.

DPP4 in Diabetes

Dipeptidyl-peptidase 4 (DPP4) is a glycoprotein of 110 kDa, which is ubiquitously expressed on the surface of a variety of cells. This exopeptidase selectively cleaves N-terminal dipeptides from a variety of substrates, including cytokines, growth factors, neuropeptides, and the incretin hormones. Expression of DPP4 is substantially dysregulated in a variety of disease states including inflammation, cancer, obesity, and diabetes. Since the incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide (GIP), are major regulators of post-prandial insulin secretion, inhibition of DPP4 by the gliptin family of drugs has gained considerable interest for the therapy of type 2 diabetic patients. In this review, we summarize the current knowledge on the DPP4–incretin axis and evaluate most recent findings on DPP4 inhibitors. Furthermore, DPP4 as a type II transmembrane protein is also known to be cleaved from the cell membrane involving different metalloproteases in a cell-type-specific manner. Circulating, soluble DPP4 has been identified as a new adipokine, which exerts both para- and endocrine effects. Recently, a novel receptor for soluble DPP4 has been identified, and data are accumulating that the adipokine-related effects of DPP4 may play an important role in the pathogenesis of cardiovascular disease. Importantly, circulating DPP4 is augmented in obese and type 2 diabetic subjects, and it may represent a molecular link between obesity and vascular dysfunction. A critical evaluation of the impact of circulating DPP4 is presented, and the potential role of DPP4 inhibition at this level is also discussed.