Concentrations Of Sitagliptin Research Articles

Sitagliptin Alleviates Obesity in Immature Mice by Inhibiting Oxidative Stress and Inflammation.

To investigate the impact of Sitagliptin against obesity and the underlying mechanism. Obese immature mice were treated with 10, 30, and 90mg/kg Sitagliptin, respectively. The body weights were recorded and the level of serum biochemical indexes were detected. The visceral fat ratio of each mouse was determined. The pathological change in adipose tissues was determined by HE staining, while F4/80 and CD206 levels in adipose tissues were determined by the immunohistochemical analysis. Lipid formation was evaluated by Oil red O staining assay. RAW264.7 cells were stimulated using oxLDL, followed by being incubated with different concentrations of Sitagliptin. The release of ADPN, IL-6, IL-1β, TNF-α, and the activity of SOD, was measured by ELISA assay. Western blotting was applied to determine adipsin, Nrf2, Keap1, and HO-1 protein levels. ROS level was checked using the DCFH-DA assay. RT-PCR assay was utilized to detect the mRNA levels of IL-6, IL-1β, TNF-α, Nrf2, Keap1, and HO-1. The body weight gain, infiltration of multinucleated cells, enlarged size of adipocytes, increased lipid accumulation, elevated visceral fat ratio, declined ADPN level, upregulated adipsin, and disordered serum biochemical indexes in obese immature mice were statistically significantly reversed by Sitagliptin. Excessive release of inflammatory factors and upregulated F4/80 and CD206 were observed in obese immature mice, which were statistically significantly repressed by Sitagliptin. Furthermore, the elevated MDA level, increased SOD activity, and inhibited Nrf2 pathway in obese immature mice were significantly reversed by Sitagliptin. In oxLDL stimulated RAW264.7 cells, increased release of inflammatory factors, ROS, and MDA, elevated SOD activity, and inactivated Nrf2 pathway were observed, which were statistically significantly abolished by the treatment of Sitagliptin. Sitagliptin alleviated obesity in immature mice by inhibiting inflammation and oxidative stress.

Effects of sitagliptin activation of the stromal cell-derived factor-1/CXC chemokine receptor 4 signaling pathway on the proliferation, apoptosis, inflammation, and osteogenic differentiation of human periodontal ligament stem cells induced by lipopolysaccharide.

This study aimed to investigate the effects of sitagliptin on the proliferation, apoptosis, inflammation, and osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) in lipopolysaccharide (LPS)-induced inflammatory microenvironment and its molecular mechanism. hPDLSCs were cultured in vitro and treated with different concentrations of sitagliptin to detect cell viability and subsequently determine the experimental concentration of sitagliptin. An hPDLSCs inflammation model was established after 24 h of stimulation with 1 µg/mL LPS and divided into blank, control, low-concentration sitagliptin (0.5 µmol/L), medium-concentration sitagliptin (1 µmol/L), and high-concentration sitagliptin (2 µmol/L), high-concentrationsitagliptin+stromal cell derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) pathway inhibitor (AMD3100) (2 µmol/L+10 µg/mL) groups. A cell-counting kit-8 was used to detect the proliferation activity of hPDLSCs after 24, 48, and 72 h culture. The apoptosis of hPDLSCs cultured for 72 h was detected by flow cytometry. After inducing osteogenic differentiation for 21 days, alizarin red staining was used to detect the osteogenic differentiation ability of hPDLSCs. The alkaline phosphatase (ALP) activity in hPDLSCs was determined using a kit. The levels of inflammatory factors [tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6] in the supernatant of hPDLSCs culture were detected by enzyme-linked immunosorbent assay. The mRNA expressions of osteogenic differentiation genes [Runt-associated transcription factor 2 (RUNX2), osteocalcin (OCN), osteopontin (OPN)], SDF-1 and CXCR4 in hPDLSCs were detected by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR). Western blot analysis was used to determine SDF-1 and CXCR4 protein expression in hPDLSCs. Compared with the blank group, the proliferative activity, number of mineralized nodules, staining intensity, ALP activity, and RUNX2, OCN, OPN mRNA, SDF-1, and CXCR4 mRNA and protein expression levels of hPDLSCs in the control group significantly decreased. The apoptosis rate and levels of TNF-α, IL-1β, and IL-6 significantly increased (P<0.05). Compared with the control group, the proliferative activity, number of mineralized nodule, staining intensity, ALP activity, and RUNX2, OCN, OPN mRNA, SDF-1, and CXCR4 mRNA and protein expression levels of hPDLSCs in low-, medium-, and high-concentration sitagliptin groups increased. The apoptosis rate and levels of TNF-α, IL-1β, and IL-6 decreased (P<0.05). AMD3100 partially reversed the effect of high-concentration sitagliptin on LPS-induced hPDLSCs (P<0.05). Sitagliptin may promote the proliferation and osteogenic differentiation of hPDLSCs in LPS-induced inflammatory microenvironment by activating the SDF-1/CXCR4 signaling pathway. Furthermore, it inhibited the apoptosis and inflammatory response of hPDLSCs.

Antioxidant and apoptotic activities of sitagliptin against hepatocellular carcinoma: An in vitro study

Background: Hepatocellular carcinoma (HCC) is the most common and aggressive type of liver cancer. Most chemotherapeutic medications nowadays imply oxidative stress leading to toxicity, which causes the necessity to find agents with better safety profiles against normal cells in addition to their anticancer activity. Sitagliptin has been shown to possess antioxidant as well as apoptotic properties by the specific suppression of dipeptidyl-peptidase 4, a glycoprotein produced in many tissues that have been thought to promote tumorigenesis and metastasis. Methods: Five groups of cell lines were included: Control (untreated HepG2 cells); cisplatin treatment HepG2 cells; sitagliptin treated HepG2 cells; combination of different concentrations of cisplatin plus sitagliptin (250 μg/mL) treated HepG2 cells, and finally, combination of different concentrations of sitagliptin plus cisplatin (25 μg/mL)-treated HepG2 cells. After an incubation period for 48 hours, the supernatants were collected to quantify the level malondialdehyde (MDA) and B-cell lymphoma-2 (BCL-2) by ELISA assay kits. Data were finally gathered and analyzed statistically. Results: Our findings indicated that sitagliptin significantly decreased the oxidative stress, particularly at high concentrations, through decreasing the MDA level. In addition, sitagliptin exhibited significant apoptotic activity against HepG2 cells through decreasing BCL-2 level. In combination with cisplatin, sitagliptin significantly potentiated the apoptotic effect and reduced the oxidative stress parameters. Conclusions: Sitagliptin showed apoptotic and antioxidant activity against HCC which may potentiate chemotherapeutic agents like cisplatin, in addition to reducing the oxidative stress against normal cells.

Pharmacokinetic comparison of sitagliptin and metformin HCl extended-release tablets versus JANUMET® XR in healthy volunteers under fasting and fed conditions.

Background and Objectives: Janumet® XR is the combination of sitagliptin and extended metformin hydrochloride produced by Merck Sharp & Dohme. It is specially designed for diabetes mellitus patients taking both drugs already. Janumet® XR exhibited clinically significant blood glucose lowering efficacy and long-term use safety. However, no generic form of Janumet® XR has been approved in western countries. The relatively high cost made the medication less prescribed. A more affordable form of this drug may benefit an immense diabetes mellitus population. The current study compared the bioequivalence (BE) of sitagliptin 100mg and metformin 1000mg produced by Nanjing Chia-Tai Tianqing Pharmaceutical Company to Janumet® XR in healthy Chinese subjects. Methods: Twenty-eight healthy Chinese subjects were enrolled in Study 1 and 2, respectively. Both studies were conducted with an open, randomized, two-period crossover design using the test (T) or the reference (R) drug. Study 1 is conducted under the fasting state, and Study 2 is under the fed state. Subjects received an oral dose of sitagliptin 100mg and metformin 1000mg, and plasma concentrations of sitagliptin and metformin were determined up to 72h post-dose. Pharmacokinetic (PK) parameters, including maximum serum concentration (Cmax) and area under the concentration-time curve up to the last quantifiable concentration (AUC0-t) of both sitagliptin and metformin, were calculated and compared between the T and R treatments. Results: In the fasting study, the geometric mean ratios of Cmax, AUC0-t, and AUC0-∞ for sitagliptin were 109.42%, 101.93%, and 101.95%, respectively; the corresponding ratios for metformin were 98.69%, 94.12%, and 93.42%, respectively. In the fed study, the geometric mean ratios of Cmax, AUC0-t, and AUC0-∞ for sitagliptin were 98.41%, 100.30%, and 100.24%, respectively; the corresponding ratios for metformin were 97.79%, 99.28%, and 100.69%, respectively. The 90% CIs of Cmax, AUC0-t, and AUC0-∞ in both studies were all within acceptance limits (80.00%-125.00%). Conclusion: The results demonstrated for the first time that sitagliptin 100mg and metformin 1000mg produced by Nanjing Chia-Tai Tianqing Pharmaceutical Company was bioequivalent to the branded Janumet® XR, and both drugs were well tolerated.

Development and Validation of an Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry method with Liquid-Liquid Extraction for The Quantification of Sitagliptin in Human plasma using Nebivolol as Internal Standard

We aimed to investigate the performance of the development method for sitagliptin quantification analysis in human plasma by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS) using liquid-liquid extraction (LLE) and Nebivolol as internal standard (IS). The parameters of this presented validation method are selectivity, the lower limit of quantification (LLOQ), linearity, accuracy, precision with five different concentration (LLOQ, Low QC, Medium QC, High QC, Upper Limit Of Quantification (ULOQ)), Integrity of dilution, matrix effect, and test for stability. Based on this study, the multiple reaction monitoring (MRM) transitions were m/z 408,23 → 127,02 for Sitagliptin and m/z 406,25 → 151,06 for IS Nebivolol. The selectivity test obtained % interference of sitagliptin and IS nebivolol by (0.00 - 0.38) % and (0.04 - 0.24) %, respectively. LLOQ test obtained a concentration value of 10.32 ng/mL and % RSD (n = 5) of 5.27 %. When the Sitagliptin concentration ranged from 1 to 1000 ng/mL, the method showed strong linearity with a coefficient of correlation of 0.9991. Accuracy test obtained % differentiation of (-12.58 - 7.77) % and precision test obtained % RSD of (1.62 - 5.32) %. The dilution integrity test obtained % differentiation at 4 and 2 times dilution was -9.20 % and -9.16 %. Matrix effect and stability data were in line with the stipulated European Medicines Agency (EMA) guidelines for validating the bioanalytical method.

Pharmacokinetics and Bioequivalence of Sitagliptin Phosphate/Metformin Hydrochloride Tablets in Healthy Chinese Subjects: A Randomized, Open-Label, Crossover Study.

ObjectiveOur objective was to evaluate the pharmacokinetics and bioequivalence of test and reference (JANUMET®) formulations of sitagliptin phosphate/metformin hydrochloride tablets at a single dose of 50 mg/850 mg.MethodsThe study was a randomized, open-label, two-period, double-crossover trial. Volunteers under fasting (n = 24) and fed (n = 24) conditions were given a single oral dose of test or reference formulations of sitagliptin phosphate/metformin hydrochloride tablets 50 mg/850 mg. We used the liquid chromatography tandem mass spectrometry method to determine the concentrations of sitagliptin and metformin in the plasma of subjects. Pharmacokinetic metrics were calculated using the WinNonlin 7.0 program, and bioequivalence was evaluated using SAS 9.4.ResultsUnder the fasting condition, the 90% confidence intervals (CIs) of geometric mean ratio for maximum plasma drug concentration (Cmax), area under the plasma concentration–time curve from time zero to time t (AUC0–t), and AUC from time zero to infinity (AUC0–∞) of sitagliptin between the test and reference groups were 101.70–120.62%, 99.81–105.61%, and 100.27–106.12%, respectively; for metformin, they were 90.39–111.48%, 94.76–109.12%, and 95.76–110.38%, respectively. Under the fed condition, they were 102.12–117.31%, 100.80–107.81%, and 100.82–107.78%, respectively, for sitagliptin and 95.53–105.22%, 92.76–103.07%, and 93.40–104.14%, respectively, for metformin. Both were generally well-tolerated.ConclusionThe two formulations of sitagliptin phosphate/metformin hydrochloride tablets were bioequivalent under fasting and fed conditions in healthy Chinese subjects.

Sitagliptin attenuates endothelial dysfunction independent of its blood glucose controlling effect

Although the contributions of sitagliptin to endothelial dysfunction in diabetes mellitus were previously reported, the mechanisms still undefined. Autophagy plays an important role in the development of diabetes mellitus, but its role in diabetic macrovascular complications is unclear. This study aims to observe the effect of sitagliptin on macrovascular endothelium in diabetes and explore the role of autophagy in this process. Diabetic rats were induced through administration of high-fat diet and intraperitoneal injection of streptozotocin. Then diabetic rats were treated with or without sitagliptin for 12 weeks. Endothelial damage and autophagy were measured. Human umbilical vein endothelial cells were cultured either in normal glucose or in high glucose medium and intervened with different concentrations of sitagliptin. Rapamycin was used to induce autophagy. Cell viability, apoptosis and autophagy were detected. The expressions of proteins in c-Jun N-terminal kinase (JNK)-Bcl-2-Beclin-1 pathway were measured. Sitagliptin attenuated injuries of endothelium in vivo and in vitro. The expression of microtubuleassociated protein 1 light chain 3 II (LC3II) and beclin-1 were increased in aortas of diabetic rats and cells cultured with high-glucose, while sitagliptin inhibited the over-expression of LC3II and beclin-1. In vitro pre-treatment with sitagliptin decreased rapamycin-induced autophagy. However, after pretreatment with rapamycin, the protective effect of sitagliptin on endothelial cells was abolished. Further studies revealed sitagliptin increased the expression of Bcl-2, while inhibited the expression of JNK in vivo. Sitagliptin attenuates injuries of vascular endothelial cells caused by high glucose through inhibiting over-activated autophagy. JNK-Bcl-2-Beclin-1 pathway may be involved in this process.

Development and Validation of a Novel RP-HPLC Analytical Method for Sitagliptin Determination in Human Plasma

Background: Different bio-analytic methods have been developed for determining drug concentration in plasma, but methods for sitagliptin determination are still very rare. In this study, RP-HPLC based method has been developed for assessing sitagliptin concentration in plasma.&#x0D; Aim: To develop and validate RP-HPLC based analytical method for estimating sitagliptin in human plasma for pharmacokinetic applications.&#x0D; Methods: In the present study, the mobile phase composed of acetonitrile: 0.5% triethanolamine (20:80) with pH 6.5 has been utilized. Samples of plasma containing sitagliptin and internal standard (IS)-rosiglitazone were extracted with dichloromethane:diethyl ether (4:6; v/v) at pH 7.4. The rate of flow was 1 ml/min. The retention time was about 5,232 and 6,903 minutes respectively for sitagliptin and rosiglitazone.&#x0D; Results: At concentrations of 100-3200 ng/ml in plasma, calibration curves of sitagliptin were linear. The inter- and intra-day precision and accuracy ranged in between 93.56-98.56% and 1.09-4.55% respectively. For specificity, the study findings showed no co-eluting peaks occurring with IS drug (rosiglitazone) and confirmed that no percentage of interferences at analyte (sitagliptin) retention in presence of rosiglitazone. The sitagliptin recovery was 96.442%. Chromatographic separations were performed on HI Qsil C-18 HS column (250mm x 4.6mm x 5μm). The stability of stock solutions of sitagliptin and IS at room temperature was 98.06% and 100.79% respectively while under refrigerated conditions stability was 98.19% and 96.59% respectively. Freeze-thaw stability for sitagliptin was performed with low &amp; high QC and shown as 98.26% for and 97.45% respectively. The limits of detection and quantification were 8.592 ng/ml and 28.641 ng/ml respectively.&#x0D; Conclusion: A simple, sensitive and accurate method was developed for bio analytical estimation of sitagliptin in human plasma using liquid-liquid extraction technique. The validation results of linearity, accuracy, precision, stability, selectivity, ruggedness, LOD and LOQ were good under acceptable limit and can be applied for pharmacokinetic studies.

Sitagliptin inhibits lipopolysaccharide-induced inflammatory response in human gingival fibroblasts by blocking nuclear factor-κB signaling pathway

This study was performed to clarify the effects of sitagliptin on Porphyromonas gingivalis-lipopolysaccharide (LPS)-induced inflammatory response in human gingival fibroblasts (HGFs), explore the molecular mechanism of its roles, and provide a foundation for clinical therapeutics in periodontitis. Healthy gingival samples were collected from the donors. HGFs were isolated with enzymic digestion method and identified. The effects of LPS and sitagliptin on cell viability were detected by cell-counting kit-8 (CCK8). The mRNA levels of inflammatory cytokines, namely, interleukin (IL)-6, IL-8, C-C motif ligand 2 (CCL2), and superoxide dismutase 2 (SOD2), were evaluated by quantity real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immune sorbent assay (ELISA) was used to measure the secretion protein levels of IL-6, IL-8, and CCL2. Western blot analysis was used to further investigate the activation of nuclear factor (NF)-κB signaling pathway. The effect of NF-κB pathway inhibitor BAY11-7082 on LPS-induced HGF inflammatory cytokines at the gene level was verified by qRT-PCR. Low concentrations of sitagliptin (0.1, 0.25, and 0.5 µmol·L-1) did not affect HGF growth in 24 and 48 h, whereas high concentrations of sitagliptin (5-1 000 µmol·L-1) significantly inhibited cell proliferation. Sitagliptin suppressed 5 µg·mL-1 of LPS-induced IL-6, IL-8, CCL2, and SOD2 gene expression levels in HGF in a concentration-dependent manner. Furthermore, sitagliptin significantly decreased the elevated secretion of IL-6, IL-8, and CCL2 protein induced by LPS. Western blot analysis showed that 0.5 µmol·L-1 of sitagliptin significantly inhibited LPS-induced NF-κB signaling pathway activation. Results of qRT-PCR analysis indicated that 0.5 µmol·L-1 of sitagliptin and 5 µmol·L-1 of BAY11-7082 significantly inhibited LPS-induced IL-6, IL-8, CCL2, and SOD2 gene expressions. Sitagliptin could significantly inhibit LPS-induced HGF inflammatory response by blocking the NF-κB signaling pathway activation.

Genetic Study on the Effect of the Antidiabetic Drug ( Sitagliptin) on DNA and Chromosomes of Human Lymphocyte Culture

AbstractBackground: Diabetes mellitus is a worsening worldwide health problem. It constitutes a major global health concern. Sitagliptin selectively inhibits dipeptidyl peptidase-4 (DPP-4) to manage type 2 diabetes mellitus (T2DM). It regulates the blood glucose level without risk of hypoglycemia or increase in body weight. In our study we investigated the effects of Sitagliptin on DNA and chromosomes in cultured human lymphocytes. Aim: To assess the genotoxic and cytotoxic effects of different concentrations of Sitagliptin on cultured human lymphocytes.Material and methods: Cultures were divided into 6 groups: control, positive control (Cisplatin) at concentration of 10 μg/mL and 4 different concentrations of Sitagliptin (125,250,500,1000 μg/mL). Sitagliptin genotoxicity and cytotoxicity were determined by using chromosomal aberrations (CAs), mitotic index (MI), comet assay and nucleic acids electrophoresis.Results: There was high significant increase in total chromosomal aberrations (TCAs) at 500, 1000 μg/mL of Sitagliptin compared to control. Other studied concentrations of Sitagliptin exhibited an increase in TCAs without significant relation. Compared to control, there was a significant increase in mitotic index at 125 μg/mL of Sitagliptin but non-significant increase at 250 μg/mL of Sitagliptin. However, at 500, 1000 μg/mL of Sitagliptin, there was a significant decrease in MI. Regarding comet assay, there was significant and high significant increase in total DNA damage at 500,1000 μg/mL of Sitagliptin respectively. Nucleic acids electrophoresis not digested with RNase showed that optical density value of RNA was maximum at 125 μg/mL then gradually decreased till reach the minimum level at 1000 μg/mL of Sitagliptin indicating its toxicity. Genomic DNA fragmentation results indicated that Sitagliptin caused a slight damage of DNA in the form of necrosis in a concentration dependent manner. Conclusion: Sitagliptin induces significant genotoxic and cytotoxic effects on the cultured human lymphocytes at concentrations of (500, 1000 μg/mL).

Highly Sensitive Adsorptive Stripping Voltammetric Method for Sitagliptin Determination on Renewable Amalgam Film Electrode

Highly sensitive voltammetric method for sitagliptin (STG) determination was developed. As working electrode cyclic renewable amalgam film electrode Hg(Ag)FE was used (surface area 10.4 mm2). Application of Hg(Ag)FE allowed to improve sensitivity of the method in comparison with HMDE. Instrumental parameters were optimized and were as follow: waiting and sampling time tw = tp = 10 ms, step potential Es = 5 mV and pulse amplitude ΔE = 50 mV. Preconcentration step was carried out at the potential equal to −600 mV for 15 s. Supporting electrolyte was optimized: 0.025 M ammonium buffer (pH 8.2). Conducted calibration allowed to determine linear range: 20–140 nM and limit of detection LOD: 2.6 nM (1.3 ng ml−1) (20 s preconcentration time). Based on linear sweep voltammetry (LSV) measurements the possible mechanism of sitagliptin reduction has been proposed. The applicability of the method was confirmed by analysis of commercially available pharmaceutical product containing sitagliptin. Obtained results were in a good agreement with producer’s declaration. Calculated recoveries (102%–107%) proved the accuracy of the method. Signal repeatability expressed as RSD was equal to 3.2% (STG concentration 0.1 μM, n = 5).

Raman spectroscopy for the qualitative and quantitative analysis of solid dosage forms of Sitagliptin.

To demonstrate the potential of Raman spectroscopy for the qualitative and quantitative analysis of solid dosage pharmacological formulations, different concentrations of Sitagliptin, an Active Pharmaceutical Ingredient (API) currently prescribed as an anti-diabetic drug, are characterised. Increase of the API concentrations induces changes in the Raman spectral features specifically associated with the drug and excipients. Principal Component Analysis (PCA) and Partial Least Squares Regression (PLSR), were used for the qualitative and quantitative analysis of the spectral responses. A PLSR model is constructed which enables the prediction of different concentrations of drug in the complex excipient matrices. During the development of the prediction model, the Root Mean Square Error of Cross Validation (RMSECV) was found to be 0.36mg and the variability explained by the model, according to the (R2) value, was found to be 0.99. Moreover, the concentration of the API in the unknown sample was determined. This concentration was predicted to be 64.28/180mg (w/w), compared to the 65/180mg (w/w). These findings demonstrate Raman spectroscopy coupled to PLSR analysis to be a reliable tool to verify Sitagliptin contents in the pharmaceutical samples based on calibration models prepared under laboratory conditions.

Repurposing anti-diabetic drug "Sitagliptin" as a novel virulence attenuating agent in Serratia marcescens.

BackgroundSerratia marcescens is an emerging pathogen that causes a variety of health care associated infections. S. marcescens is equipped with an arsenal of virulence factors such as biofilm formation, swimming and swarming motilities, prodigiosin, protease and others which enable it to initiate and cause the infection. These virulence factors are orchestrated under the umbrella of an intercellular communication system named Quorum sensing (QS). QS allows bacterial population to synchronize the expression of virulence genes upon detection of a chemical signaling molecule. Targeting bacterial virulence is a promising approach to attenuate bacteria and enhances the ability of immune system to eradicate the bacterial infection. Drug repurposing is an advantageous strategy that confers new applications for drugs outside the scope of their original medical use. This promising strategy offers the use of safe approved compounds, which potentially lowers the costs and shortens the time than that needed for development of new drugs. Sitagliptin is dipeptidyl peptidase-4 (DPP-4) inhibitor, is used to treat diabetes mellitus type II as it increases the production of insulin and decreasing the production of glucagon by the pancreas. We aimed in this study to repurpose sitagliptin, investigating the anti-virulence activities of sitagliptin on S. marcescens.MethodsThe effect of sub-inhibitory concentrations of sitagliptin on virulence factors; protease, prodigiosin, biofilm formation, swimming and swarming motilities was estimated phenotypically. The qRT-PCR was used to show the effect of sitagliptin on the expression of QS-regulated virulence genes. The in-vivo protective activity of sitagliptin on S. marcescens pathogenesis was evaluated on mice.ResultsSitagliptin (1 mg/ml) significantly reduced the biofilm formation, swimming and swarming motilities, prodigiosin and protease. The qRT-PCR confirmed the effect on virulence as shown by down regulating the expression of fimA, fimC, flhC, flhD, bsmB, rssB, rsmA, pigP, and shlA genes. Moreover, the in-vivo findings showed the efficient ability of sitagliptin to weaken S. marcescens pathogenesis.ConclusionSitagliptin is a promising anti-virulence agent against S. marcescens that may be beneficial in the control of healthcare associated infections caused by S. marcescens.

Investigation of in vitro genotoxic effects of an anti-diabetic drug sitagliptin

Sitagliptin is an active ingredient of antidiabetic drug used in the treatment of type 2 diabetes mellitus (T2DM). In this study, the genotoxic effects of sitagliptin were determined in human lymphocytes by using chromosome aberrations (CAs), sister chromatid exchanges (SCEs), micronucleus (MN) and comet assays. 31.25–1000 μg/mL concentrations of sitagliptin were used. Sitagliptin significantly increased the frequency of CAs and SCEs at the highest concentration at 24 h treatment and all concentrations (except 250 μg/mL for CA, except 31.25 and 62.50 μg/mL for SCE) at 48 h treatment compared with solvent control (DMSO). This compound increased the MN at only the highest concentration compared with the solvent control. Mitotic index (MI) significantly decreased at the three highest concentrations of sitagliptin at 48 h treatment. However, replication (RI) and nuclear division (NDI) indices were not affected at all the treatments. Comet assay results indicated that sitagliptin significantly increased mean comet tail intensity and tail moment at only two concentrations (62.50 and 1000 μg/mL for intensity, 125 and 1000 μg/mL for tail moment), and tail length at all concentrations (except 125 and 500 μg/mL). It was concluded that higher concentration of sitagliptin had genotoxic effects in the human lymphocytes in vitro.

An open-label, multiple-dose study to assess the pharmacokinetics and tolerability of sitagliptin/metformin fixed-dose combination (FDC) tablet in healthy Chinese adult subjects.

This study investigated the pharmacokinetics of sitagliptin and metformin after multiple oral doses of the sitagliptin/metformin fixed-dose combination (MK0431A) tablet in healthy Chinese volunteers. This was a singlecenter, randomized study in 24 healthy adults. Subjects received twice-daily doses of MK0431A 50-mg/500-mg tablet and 50-mg/850-mg tablet for 7 days. Serial blood and urine samples were collected at predefined time points for bioassay of sitagliptin and metformin. Safety was assessed throughout the study. Based on consecutive trough concentrations, the steady states of sitagliptin and metformin were reached after twice-daily administration of MK0431A tablets for 5 days. After the last dose, the mean ± SD (standard deviation) peak sitagliptin concentration of 167.3 - 22.52 and 174.1 ± 22.16 ng/mL was reached in a median t_max of 2.25 - 3 hours. The mean ± SD Cmax of metformin appeared in a median tmax of 1.75 - 2.25 hours at 888.3 ± 195.19 and 1,337 ± 269.19 ng/mL with MK0431A 50 mg/500 mg and 50 mg/850 mg, respectively Mean ± SD AUC012h of sitagliptin was between 1,404 ± 147.48 and 1,374 ± 179.12 h×ng/mL, while mean ± SD AUC0-12h of metformin were 6,015 ± 854.98 and 8,587 ± 1,715.93 h×ng/mL with MK0431A 50 mg/500 mg and 50 mg/850 mg, respectively. Approximately 75% sitagliptin and 40% metformin were excreted unchanged in the urine, corresponding to a renal clearance of 17.84 - 18.27 L/h for sitagliptin and 27.11 - 27.94 L/h for metformin. No clinically-significant pharmacokinetic difference was identified between Chinese and foreign healthy volunteers regarding sitagliptin and metformin with multiple doses of MK0431A tablets. The treatments were well tolerated.

Renoprotective effect of DPP-4 inhibitors against free fatty acid-bound albumin-induced renal proximal tubular cell injury

Dipeptidyl peptidase (DPP)-4 inhibitors, a new class of antidiabetic agent, have recently been suggested to exert pleiotropic effects beyond glucose lowering. Renal prognosis in patients with diabetic nephropathy depends on the severity of tubulointerstitial injury induced by massive proteinuria. We thus examined the renoprotective effect of DPP-4 inhibitors on inflammation in cultured mouse proximal tubular cells stimulated with free fatty acid (FFA)-bound albumin. Linagliptin and higher concentrations of sitagliptin, vildagliptin, and alogliptin all inhibited FFA-bound albumin-induced increases in mRNA expression of MCP-1 in cultured mouse proximal tubular cells. Furthermore, linagliptin significantly inhibited tubulointerstitial injury induced by peritoneal injection of FFA-bound albumin, such as inflammation, fibrosis, and apoptosis, in mice without altering systemic characteristics including body weight, fasting blood glucose, and food intake. These results indicate that DPP-4 inhibitors pleiotropically exert a direct renoprotective effect, and may serve as an additional therapeutic strategy to protect proximal tubular cells against proteinuria in patients with diabetic nephropathy.

Developing imprinted polymer nanoparticles for the selective separation of antidiabetic drugs.

In this study, new molecularly imprinted polymer (MIP) nanoparticles are designed for selective recognition of different drugs used for the treatment of type 2 diabetes mellitus, i.e. sitagliptin (SG) and metformin (MF). The SG- and MF-imprinted polymer nanoparticles are synthesized by free-radical initiated polymerization of the functional monomers: methacrylic acid and methyl methacrylate; and the crosslinker: ethylene glycol dimethacrylate. The surface morphology of resultant MIP nanoparticles is studied by atomic force microscopy. Fourier transform infrared spectra of MIP nanoparticles suggest the presence of reversible, non-covalent interactions between the template and the polymer. The effect of pH on the rebinding of antidiabetic drugs with SG- and MF-imprinted polymers is investigated to determine the optimal experimental conditions. The molecular recognition characteristics of SG- and MF-imprinted polymers for the respective drug targets are determined at low concentrations of SG (50-150 ppm) and MF (5-100 ppm). In both cases, the MIP nanoparticles exhibit higher binding response compared to non-imprinted polymers. Furthermore, the MIPs demonstrate high selectivity with four fold higher responses toward imprinted drugs targets, respectively. Recycled MIP nanoparticles retain 90% of their drug-binding efficiency, which makes them suitable for successive analyses with significantly preserved recognition features.

Effect of sitagliptin on lipopolysaccharide-induced changes in the mass and function of islet β cells

Objective To investigate the effect of dipeptidyl peptidase-4(DPP-4)inhibitor on lipopolysaccharide(LPS)-induced changes in the mass and function of pancreatic β-cells. Methods RINm cells were cultured and treated with LPS alone or combined with different concentrations of sitagliptin for 24 h. The proliferation of RINm cells was detected by CCK-8 assay. Apoptotic rate was determined by Annexin V-fluorescein isothiocyanate(FITC)/propidium iodide flow cytometry. Insulin secretion was measured by enzyme-linked immunosorbent assay. The expression of IL-6 mRNA was displayed by RT-PCR. Results LPS significantly stimulated the proliferation of RINm cells(0.89±0.04 vs 1.14±0.08, P<0.01), while LPS+ sitagliptin showed no significant difference compared with LPS group. The cell apoptotic rate in LPS+ 10-1mmol/L sitagliptin group was significantly lower than that in LPS group. There were no significant differences in basal insulin secretion among all groups, but after the high/low glucose stimulation, LPS increased insulin secretion as compared with the control. The IL-6 mRNA expression in LPS+ sitagliptin group was significantly lower than that in LPS group(0.77±0.33 vs 1.30±0.41, P=0.006). Conclusions DPP-4 inhibitor has no influence on LPS-induced proliferation of pancreatic β-cell, but it can inhibit LPS-induced apoptosis and insulin secretion, and IL-6 may be involved in the process. (Chin J Endocrinol Metab, 2015, 31: 447-451) Key words: Dipeptidyl peptidase-4 inhibitor; Lipopolysaccharide; Pancreatic β-cell

Pharmacokinetic-Pharmacodynamic Modelling of Biomarker Response to Sitagliptin in Healthy Volunteers

Pharmacokinetic/pharmacodynamic (PK/PD) models can be useful tools in new drug development and also optimal drug therapy in patients. This study was designed to develop a PK/PD model of sitagliptin based on the physiology of incretin. The PK/PD data included information derived from two different studies. Study 1 was conducted as a one-sequence, three-period, repeated-dose, dose escalation (sitagliptin 25, 50 and 100mg q.d.) design in twelve healthy volunteers. Study 2 was a first-in-man study for the newly developed dipeptidyl peptidase-4 (DPP-4) inhibitor in healthy volunteers. In study 1, blood samples were collected to measure sitagliptin concentrations, DPP-4 activity and active glucagon-like peptide-1 (GLP-1) concentrations. In study 2, only data from the 'placebo group' were used, and blood samples were collected to measure DPP-4 activity, active GLP-1 concentrations and glucose concentrations. A PK/PD analysis was conducted using a non-linear mixed effects modelling approach. Sitagliptin pharmacokinetics was modelled using a two-compartment model with first-order absorption. Changes in DPP-4 inhibition were linked to the PK model using a sigmoid Emax model, whereas the active GLP-1 changes were explained using an indirect response model; this model incorporated the glucose and DPP-4 inhibition models. The PK/PD model developed adequately described the changes in sitagliptin concentration, DPP-4 inhibition and active GLP-1 concentration in healthy volunteers.

Direct determination of sitagliptin in pharmaceutical formulations and its determination in urine after solid‐phase extraction by spectrofluorimetry

The fluorescence characteristics of sitagliptin phosphate were used to develop a methodology that allowed its determination in pharmaceutical formulations and urine samples; under the studied conditions, limits of determination and quantification of 0.25 and, respectively, 0.85 mg/L were achieved. Linear correlation between fluorescence analytical signal and sitagliptin concentration was achieved up to 10.0 mg/L. The method was considered selective for sitagliptin determination in pharmaceutical formulations because no interferences due to excipients present in considered matrix were observed (as demonstrated by recovery tests comparing analytical and addition curves). When the method was applied to urine samples, Interferences related to the matrix were observed, which made a solid-phase extraction system necessary. The use of calibration was possible only by applying the standard addition method.