Dipeptidyl Peptidase-4 Inhibitors for the Treatment of Type 2 Diabetes: Focus On Sitagliptin

Microbial dipeptidyl peptidases of the S9B family as host-microbe isozymes

Human dipeptidyl peptidase 4 (hDPP-4) has been a pharmacological target for metabolic diseases, particularly diabetes, since the early 2000s. As a ubiquitous enzyme found in both prokaryotic and eukaryotic organisms, hDPP-4 plays crucial roles in host homeostasis and disease progression. While many studies have explored hDPP-4's properties, research on gut microbially derived DPP-4 (mDPP-4) remains limited. This review discusses the significance of mDPP-4 and its health implications, analyzing crystal structures of mDPP-4 in comparison to human counterparts. We examine how hDPP-4 inhibitors could influence gut microbiome composition and mDPP-4 activity. Additionally, this review connects ongoing discussions regarding DPP-4 substrate specificity and potential access routes for mDPP-4, emphasizing the urgent need for further research on mDPP-4's role in health and improve the precision of DPP-4 inhibitor therapies.

Miniature mass spectrometer-based point-of-care assay for quantification of metformin and sitagliptin in human blood and urine

Metformin (MET) and sitagliptin (STG) are widely used as the first-line and long-term oral hypoglycemic agents for managing type 2 diabetes mellitus (T2DM). However, the current lack of convenient and rapid measurement methods poses a challenge for individualized management. This study developed a point-of-care (POC) assay method utilizing a miniature mass spectrometer, enabling rapid and accurate quantification of MET and STG concentrations in human blood and urine. By combining the miniature mass spectrometer with paper spray ionization, this method simplifies the process into three to four steps, requires minimal amounts of bodily fluids (50 μL of blood and 2 μL of urine), and is able to obtain quantification results within approximately 2 min. Stable isotope-labeled internal standards were employed to enhance the accuracy and stability of measurement. The MS/MS responses exhibited good linear relationship with concentration, with relative standard deviations (RSDs) below 25%. It has the potential to provide immediate treatment feedback and decision support for patients and healthcare professionals in clinical practice.

Efficacy and safety of the addition of sitagliptin to treatment of youth with type 2 diabetes and inadequate glycemic control on metformin without or with insulin

OBJECTIVE

To assess the efficacy and safety of sitagliptin in youth with type 2 diabetes (T2D) inadequately controlled with metformin ± insulin.

STUDY DESIGN

Data were pooled from two 54-week, double-blind, randomized, placebo-controlled studies of sitagliptin 100 mg daily or placebo added onto treatment of 10- to 17-year-old youth with T2D and inadequate glycemic control on metformin ± insulin. Participants (N = 220 randomized and treated) had HbA1c 6.5%-10% (7.0%-10% if on insulin), were overweight/obese at screening or diagnosis and negative for pancreatic autoantibodies. The primary endpoint was change from baseline in HbA1c at Week 20.

RESULTS

Treatment groups were well balanced at baseline (mean HbA1c = 8.0%, BMI = 30.9 kg/m² , age = 14.4 years [44.5% <15], 65.9% female). The dose of background metformin was >1500 mg/day for 71.8% of participants; 15.0% of participants were on insulin therapy. At Week 20, LS mean changes from baseline (95% CI) in HbA1c for sitagliptin/metformin and placebo/metformin were -0.58% (-0.94, -0.22) and -0.09% (-0.43, 0.26), respectively; difference = -0.49% (-0.90, -0.09), p = 0.018; at Week 54 the LS mean (95% CI) changes were 0.35% (-0.48, 1.19) and 0.73% (-0.08, 1.54), respectively. No meaningful differences between the adverse event profiles of the treatment groups emerged through Week 54.

CONCLUSIONS

These results do not suggest that addition of sitagliptin to metformin provides durable improvement in glycemic control in youth with T2D. In this study, sitagliptin was generally well tolerated with a safety profile similar to that reported in adults. (ClinicalTrials.gov: NCT01472367, NCT01760447; EudraCT: 2011-002529-23/2014-003583-20, 2012-004035-23).

A randomized clinical trial of the efficacy and safety of sitagliptin as initial oral therapy in youth with type 2 diabetes

OBJECTIVE

To assess the efficacy and safety of DPP-4 inhibition with sitagliptin in youth with type 2 diabetes (T2D).

STUDY DESIGN

This was a 54-week, double-blind, randomized, controlled clinical trial evaluating the safety and efficacy of DPP-4 inhibition with sitagliptin 100 mg once daily as initial oral therapy in youth with T2D. The 190 participants, aged 10-17 years, had HbA1c 6.5%-10% (7.0%-10% if on insulin). All were negative for pancreatic autoantibodies and overweight/obese at screening or diagnosis. The trial was placebo controlled for the first 20 weeks, after which metformin replaced placebo. The primary efficacy endpoint was change from baseline in HbA1c at Week 20.

RESULTS

Treatment groups were well balanced at baseline (mean ± SD HbA1c = 7.5% ± 1.0, BMI percentile = 97.1% ± 6.8, age = 14.0 years ± 2.0 [57.4% <15], 60.5% female). At Week 20, least squares mean changes from baseline in HbA1c were -0.01% (sitagliptin) and 0.18% (placebo); between-group difference (95% CI) = -0.19% (-0.68, 0.30), p = 0.448. At Week 54, the changes in HbA1c were 0.45% (sitagliptin) and -0.11 (placebo/metformin). There were no notable between-group differences in the adverse event profiles through Week 54.

CONCLUSIONS

DPP-4 inhibition with sitagliptin did not provide significant improvement in glycemic control. In this study, sitagliptin was generally well tolerated with a safety profile similar to that reported in adults. (ClinicalTrials.gov: NCT01485614; EudraCT: 2011-002528-42).

UV and (V)UV irradiation of sitagliptin in ultrapure water and WWTP effluent: Kinetics, transformation products and degradation pathway

Sitagliptin (SITA) is an antidiabetic drug consumed worldwide in high quantities. Because of the low removal rate of this compound in conventional wastewater treatment plants (WWTPs), it enters receiving surface waters with the discharged WWTP effluents. SITA can be detected up to μg/L concentration in rivers. In this study, UV (254 nm) and (V)UV (185 nm + 254 nm) irradiation was applied in laboratory scale to degrade SITA. The effect of three parameters was evaluated on the degradation rate, namely i) the efficiency in UV and (V)UV irradiation, ii) the presence or absence of dissolved oxygen, iii) the matrix effect of WWTP effluent. Degradation rate of SITA was largely increased by (V)UV irradiation, and decreased in WWTP effluent as expected. The presence of dissolved oxygen increased the degradation rate only in UV experiments and did not have a considerable effect in (V)UV experiments. In total, 14 transformation products (TPs) were identified (twelve new); their structures were proposed based on high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy analyses. The most characteristic reaction steps of the degradation of SITA involved nucleophilic aromatic photosubstitution whereas hydroxide ions acted as attacking nucleophiles and replaced F atoms of the phenyl moiety by hydroxide groups, in agreement with the increase in photolysis rate with increasing pH. The photochemical degradation pathway of SITA was also interpreted. Kinetic profiles revealed TP 421, TP 208 and TP 192 to be the most recalcitrant TPs.

Nickel-Catalyzed Asymmetric Hydrogenation for the Synthesis of a Key Intermediate of Sitagliptin

Nickel-catalyzed enantioselective hydrogenation of enamines leading to the efficient synthesis of 3-R-Boc-amino-4-(2,4,5-trifluorophenyl)butyric esters, the key intermediate of the blockbuster antidiabetic drug (R)-SITAGLIPTIN, is described. The sitagliptin motifs were isolated in more than 99% yield and with 75-92% ee using the earth-abundant nickel catalyst. Upon chiral resolution with (R)- and (S)-1-phenylethylamines, the partially enantioenriched (R)- and (S)-Boc-3-amino-4-(2,4,5-trifluorophenyl)butanoic acids provided >99.5% ee of the crucial sitagliptin intermediate. The asymmetric hydrogenation protocol was scaled up to 10 g with consistency in yield and ee, and has been reproduced in multiple batches.

A Double-Blind, Randomized, Placebo and Positive-Controlled Study in Healthy Volunteers to Evaluate Pharmacokinetic and Pharmacodynamic Properties of Multiple Oral Doses of Cetagliptin

AIMS

This study investigated the pharmacokinetics and pharmacodynamics properties, safety and tolerability of cetagliptin.

METHODS

Forty-eight healthy subjects were enrolled in this study. Three cohorts were investigated in sequential order: 50, 100 and 200 mg cetagliptin. Positive control (sitagliptin 100mg) was designed as open label. Blood samples were collected and analyzed for pharmacokinetics and pharmacodynamics properties. Safety and tolerability were assessed throughout the study.

RESULTS

Following multiple oral doses, cetagliptin was rapidly absorbed and reached peak plasma concentrations after approximately 1.0-1.5 h. Plasma cetagliptin concentrations increased at a rate greater than dose. Accumulation of cetagliptin was modest, and steady state was generally achieved at day 5. Doses ≥ 50 mg of cetagliptin administered once daily will result in sustained DPP-4 inhibition (≥ 80%). The EC₅₀ of DPP-4 inhibition for cetagliptin (5.29 ng/mL) was lower than that of sitagliptin (7.03 ng/mL). Active GLP-1 concentrations were significantly increased in the cetagliptin groups by 2.3 to 3.1fold at day 1 and 3.1 to 3.6 fold at steady state compared with that of placebo, and active GLP-1 concentrations were increased with increasing dose. Compared with sitagliptin, doses ≥ 100 mg QD of cetagliptin produced postprandial increases in active GLP-1 level and induced to long-lasting glucose-lowering efficacy. Across all doses of cetagliptin studied, cetagliptin was well tolerated.

CONCLUSION

Cetagliptin demonstrates the great potential for treatment with type 2 diabetes patients based on the inhibition of DPP-4, the increase in GLP-1 and insulin, the decrease in glucose, and might more effective in DPP-4 inhibition than sitagliptin.

Biowaiver Monograph for Immediate-Release Solid Oral Dosage Forms: Sitagliptin Phosphate Monohydrate

Sitagliptin is an antihyperglycemic drug used in adults for the treatment of diabetes Type 2. Literature data and in-house experiments were applied in this monograph to assess whether methods based on the Biopharmaceutics Classification System (BCS) could be used to assess the bioequivalence of solid immediate-release (IR) oral dosage forms containing sitagliptin phosphate monohydrate, as an alternative to a pharmacokinetic study in human volunteers. The solubility and permeability characteristics of sitagliptin were reviewed according to the BCS, along with dissolution, therapeutic index, therapeutic applications, pharmacokinetics, pharmacodynamic characteristics, reports of bioequivalence (BE) / bioavailability problems, data on interactions between the drug and excipients and other data germane to the subject. All data reviewed in this monograph unambiguously support classification of sitagliptin as a BCS Class 1 drug. In light of its broad therapeutic index and lack of severe adverse effects, the clinical risks associated with moderately supraoptimal doses were deemed inconsequential, as were the risks associated with moderately suboptimal doses. Taking all evidence into consideration, it was concluded that the BCS-based biowaiver can be implemented for solid IR oral drug products containing sitagliptin phosphate monohydrate, provided (a) the test product is formulated solely with excipients commonly present in solid IR oral drug products approved in ICH or associated countries and used in amounts commonly applied in this type of product, (b) data in support of the BCS-based biowaiver are obtained using the methods recommended by the WHO, FDA, EMA or ICH and (c) the test product and the comparator product (which is the innovator product in this case) meet all in vitro dissolution specifications provided in the WHO, FDA, EMA or ICH guidance.

Analytical quality by design in the development of a solvent-modified micellar electrokinetic chromatography method for the determination of sitagliptin and its related compounds

A solvent-modified micellar electrokinetic chromatography method was developed following the Quality by Design approach for the simultaneous determination of sitagliptin (SIT), an oral antihyperglycemic drug, and its main impurities derived from the synthesis process. The separation system was identified in the scouting phase and was made by sodium dodecyl sulphate (SDS) micelles with the addition of n-butanol and methanol. The knowledge space was investigated through an asymmetric screening matrix, taking into consideration eight critical method parameters (CMPs) involving the composition of the background electrolyte in terms of buffer concentration and pH, the concentration of surfactants and organic modifiers, and voltage. The critical method attributes (CMAs) were identified as analysis time and the distance between the tail of the electroosmotic flow system peak and the front edge of impurity I₁ (sitagliptin triazole hydrochloride). A Box-Behnken Design was used in response surface methodology for calculating the quadratic models relating the CMPs to the CMAs. From the models it was possible to compute the method operable design region (MODR) through Monte-Carlo simulations. The MODR was identified in the probability maps as the multidimensional zone where the risk of failure to achieve the desired values for the CMAs was lower than 10 %. The experimental conditions corresponding to the working point, with the MODR interval, were the following: background electrolyte, 14 (10-18) mM borate buffer pH 9.20, 100 mM SDS, 13.6 (11.1-16.0) %v/v n-butanol, 6.7 (4.5-8.8) %v/v methanol; voltage and temperature were set to 28 kV and 22 °C, respectively. The developed CE method was validated in accordance with International Council for Harmonisation guidelines and was applied to the analysis of SIT tablets. The routine analysis for the quality control of the pharmaceutical product could be conducted in about 11 min.

Clinical efficacy and plausibility of a smartphone-based integrated online real-time diabetes care system via glucose and diet data management: a pilot study

BACKGROUND

Smartphones have become novel healthcare tools for patients with diabetes. However, it is uncertain whether the smartphone application support system helps in glycaemic control in patients with type 2 diabetes.

AIMS

To evaluate the efficacy and plausibility of smartphone-based integrated online real-time diabetes care.

METHODS

Forty patients with type 2 diabetes were randomly assigned to the smartphone-based care (SC) (n = 20) and conventional care (CC) (n = 20) groups for 12 weeks. The SC group was instructed to use smartphone application (Noom Coach) and a glucose meter, and was provided medical supervision based on blood glucose level and food intake information sent to the central database server. The efficacy was evaluated by glycated haemoglobin (A1C ≤ 6.5%). The Summary of Diabetes Self-Care Activities (SDSCA) questionnaire was collected at baseline and at week 12.

RESULTS

Seventeen and 18 patients of the SC and CC groups completed the study respectively. In the SC group, more patients achieved target A1C compared with the CC group (47.1% vs 11.1%, P = 0.019). In both group, SDSCA scores excluding the exercise item showed overall improvement (general diet, 1.4 ± 2.0 → 2.6 ± 2.3 vs 0.4 ± 1.1 → 1.8 ± 2.2; specific diet, 4.2 ± 1.7 → 5.4 ± 1.2 vs 3.8 ± 1.6 → 5.1 ± 1.1; blood glucose test, 3.3 ± 2.8 → 4.9 ± 2.3 vs 1.0 ± 2.2 → 4.7 ± 2.3; foot care, 1.5 ± 1.6 → 3.6 ± 2.8 vs 1.4 ± 1.9 → 6.1 ± 1.4; all P < 0.05). There was no difference between both groups other than the aspect of foot care (P = 0.008).

CONCLUSIONS

The smartphone-based integrated online real-time diabetes care system through glucose and diet data management showed clinical plausibility in glucose control in real clinical practice.

Glucagon-like peptide-1 (GLP-1) receptor agonists and their cardiovascular benefits-The role of the GLP-1 receptor

Cardiovascular outcome trials revealed cardiovascular benefits for type 2 diabetes mellitus patients when treated with long‐acting glucagon‐like peptide‐1 (GLP‐1) receptor agonists. In the last decade, major advances were made characterising the physiological effects of GLP‐1 and its action on numerous targets including brain, liver, kidney, heart and blood vessels. However, the effects of GLP‐1 and receptor agonists, and the GLP‐1 receptor on the cardiovascular system have not been fully elucidated. We compare results from cardiovascular outcome trials of GLP‐1 receptor agonists and review pleiotropic clinical and preclinical data concerning cardiovascular protection beyond glycaemic control. We address current knowledge on GLP‐1 and receptor agonist actions on the heart, vasculature, inflammatory cells and platelets, and discuss evidence for GLP‐1 receptor‐dependent versus independent effects secondary of GLP‐1 metabolites. We conclude that the favourable cardiovascular profile of GLP‐1 receptor agonists might expand their therapeutic use for treating cardiovascular disease even in non‐diabetic populations.

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 0.36 mg 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 64.28/180 mg (w/w), compared to the 65/180 mg (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.

Dipeptidyl peptidase-4 inhibition to prevent progression of calcific aortic stenosis

OBJECTIVE

To evaluate whether the use of dipeptidyl peptidase-4 (DPP-4) inhibitors and their cardiac tissue distribution profile and anticalcification abilities are associated with risk of aortic stenosis (AS) progression.

METHODS

Out of the five different classes of DPP-4 inhibitors, two had relatively favourable heart to plasma concentration ratios and anticalcification ability in murine and in vitro experiments and were thus categorised as 'favourable'. We reviewed the medical records of 212 patients (72±8 years, 111 men) with diabetes and mild-to-moderate AS who underwent echocardiographic follow-up and classified them into those who received favourable DPP-4 inhibitors (n=28, 13%), unfavourable DPP-4 inhibitors (n=69, 33%) and those who did not receive DPP-4 inhibitors (n=115, 54%).

RESULTS

Maximal transaortic velocity (Vmax) increased from 2.9±0.3 to 3.5±0.7 m/s during follow-up (median, 3.7 years), and the changes were not different between DPP-4 users as a whole and non-users (p=0.143). However, the favourable group showed significantly lower Vmax increase than the unfavourable or non-user group (p=0.018). Severe AS progression was less frequent in the favourable group (7.1%) than in the unfavourable (29.0%; p=0.03) or the non-user (29.6%; p=0.01) group. In Cox regression analysis after adjusting for age, baseline renal function and AS severity, the favourable group showed a significantly lower risk of severe AS progression (HR 0.116, 95% CI 0.024 to 0.551, p=0.007).

CONCLUSIONS

DPP-4 inhibitors with favourable pharmacokinetic and pharmacodynamic properties were associated with lower risk of AS progression. These results should be considered in the preparation of randomised clinical trials on the repositioning of DPP-4 inhibitors.

Creation of a robust and R-selective ω-amine transaminase for the asymmetric synthesis of sitagliptin intermediate on a kilogram scale

The creation of an R-selective ω-amine transaminase (ω-ATA) as biocatalyst is crucial for the asymmetric amination of prochiral ketones to produce sitagliptin intermediates because rare ω-ATAs are R-selective in nature and most of them suffer from poor stability and low activity toward bulky prochiral ketones. Here, the gene of an R-selective ω-ATA was cloned from Arthrobacter cumminsii ZJUT212 (AcATA) and expressed in Escherichia coli. The best variants (M1 + M122H and M1+T134 G) were obtained using a semi-rational protein design after screening. These variants not only exhibited improved activity and substrate affinity but also enhanced stability in aqueous phase containing 20 % dimethyl sulfoxide. The conversion of asymmetric amination on 50 g/L pro-sitagliptin ketone PTfpB (1-[1-piperidinyl]-4-[2,4,5-trifluorophenyl]-1,3-butanedione) achieved 92 %, with an extremely high e.e. of >99 %, using 2 g_DCW/L E. coli cells harboring M1 + M122H as biocatalyst. In the kilogram-scale experiment, approximately 40 kg of (R)-APTfpB (e.e. >99 %) was produced within 30 h when 50 kg PTfpB was used as the substrate. Furthermore, the space-time yield reached ≈32 g/(L·d).

The Effects of DPP4 Inhibitors on Lipid Status and Blood Pressure in Rats with Diabetes Mellitus Type 2

The aim of the present study was to examine, evaluate and compare the effects of administered dipeptidyl peptidase-4 (DPP4) inhibitors saxagliptin and sitagliptin on lipid status parameters and blood pressure in rats with streptozotocine induced diabetes mellitus type 2. Forty-eight Wistar albino rats were divided randomly into 4 groups: 1. group I: control healthy group; 2. group II: rats with diabetes mellitus type 2; 3. group III: rats with diabetes mellitus type 2+ treated with 0.6 mg/kg of sitagliptin; 4. group IV: rats with diabetes mellitus type 2 treated with 0.45 mg/kg of saxagliptin. The rats from experimental groups were fed with a high-fat diet for 4 weeks and after 6–8 h of starvation received one dose of streptozotocin (STZ) intraperitoneally (25 mg/kg body weight) to induce type 2 diabetes mellitus (T2DM). Animals with fasting glucose above 7 mmol/L and insulin over 6 mmol/L were included in the study as rats with T2DM. Upon completion of the experiments, the blood was collected from the anesthetized animals and serum triglyceride (TG), total cholesterol (TCH), high density lipoprotein (HDL), and low density lipoprotein (LDL) were measured using spectrophotometry and commercial kits. At the beginning of the study and the day before sacrificing animals, the blood pressure and heart rate were measured by a tail-cuff noninvasive method. DPP4 inhibitors, as glucagon-like peptide-1 (GLP-1) agonists, were associated with modest reductions in DBP, LDL-C, TCH, and TGL and significant improvement in HDL, SBP and HR.

The Role of DPP-4 Inhibitors in the Treatment Algorithm of Type 2 Diabetes Mellitus: When to Select, What to Expect

Type 2 diabetes mellitus is a growing global public health problem, the prevalence of which is projected to increase in the succeeding decades. It is potentially associated with many complications, affecting multiple organs and causing a huge burden to the society. Due to its multi-factorial pathophysiology, its treatment is varied and based upon a multitude of pharmacologic agents aiming to tackle the many aspects of the disease pathophysiology (increasing insulin availability [either through direct insulin administration or through agents that promote insulin secretion], improving sensitivity to insulin, delaying the delivery and absorption of carbohydrates from the gastrointestinal tract, or increasing urinary glucose excretion). DPP-4 (dipeptidyl peptidase-4) inhibitors (or “gliptins”) represent a class of oral anti-hyperglycemic agents that inhibit the enzyme DPP-4, thus augmenting the biological activity of the “incretin” hormones (glucagon-like peptide-1 [GLP-1] and glucose-dependent insulinotropic polypeptide [GIP]) and restoring many of the pathophysiological problems of diabetes. They have already been used over more than a decade in the treatment of the disease. The current manuscript will review the mechanism of action, therapeutic utility, and the role of DPP-4 inhibitors for the treatment of type 2 diabetes mellitus.

Sitagliptin protects diabetic rats with acute myocardial infarction through induction of angiogenesis: role of IGF-1 and VEGF

Angiogenesis is regulated in a tissue-specific manner in all patients, especially those with diabetes. In this study, we describe a novel molecular pathway of angiogenesis regulation in diabetic rats with myocardial infarction (MI) and examine the cardioprotective effects of different doses of sitagliptin. Male rats were divided into 5 groups: normal vehicle group, diabetic group, diabetic + MI, diabetic + MI + 5 mg/kg sitagliptin, and diabetic + MI + 10 mg/kg sitagliptin. Isoproterenol in diabetic rats resulted in significant (p < 0.05) disturbance to the electrocardiogram, cardiac histopathological manifestations, and an increase in inflammatory markers compared with the vehicle and diabetic groups. Treatment with sitagliptin improved the electrocardiogram and histopathological sections, upregulated vascular endothelial growth factor (VEGF) and transmembrane phosphoglycoprotein protein (CD34) in cardiac tissues, and increased serum insulin-like growth factor 1 (IGF-1) and decreased cardiac tissue homogenate for interleukin 6 (IL-6) and cyclooxygenase 2 (COX-2). A relationship was found between serum IGF-1 and cardiac VEGF and CD34 accompanied by an improvement in cardiac function of diabetic rats with MI. Therefore, the observed effects of sitagliptin occurred at least partly through an improvement in angiogenesis and the mitigation of inflammation. Consequently, these data suggest that sitagliptin may contribute, in a dose-dependent manner, to protection against acute MI in diabetic individuals.

Incretin-based therapies for patients with type 1 diabetes: a meta-analysis

OBJECTIVE

Combined treatment with an incretin-based drug, such as a glucagon-like peptide 1 receptor agonist (GLP-1 RA) or a dipeptidyl peptidase-4 (DPP-4) inhibitor, and basal insulin is a new strategy for improving glucose control in type 1 diabetes mellitus (T1DM). We performed a meta-analysis to assess the effect of this combined treatment on glycaemic control, insulin dose, severe hypoglycaemia, weight gain and gastrointestinal side effects in T1DM patients.

METHODS

We searched PubMed, EMBASE and the Cochrane Library for relevant studies published before July 16, 2018. The primary outcome was glycosylated haemoglobin (HbA1c). Secondary outcomes included total daily insulin dose, body weight, severe hypoglycaemia and gastrointestinal side effects.

RESULTS

Nine randomized controlled trials (RCTs) involving 2389 patients were ultimately included in the meta-analysis. The pooled data suggested that incretin-based therapy was associated with a reduction in HbA1c levels (weighted mean difference (WMD) -0.17%, 95% confidence interval (CI) -0.24 to -0.11, P < 0.001), total daily insulin dose (WMD -5.53 IU/day, 95% CI -8.89 to -2.17, P = 0.001) and body weight (WMD -3.24 kg, 95% CI -4.43 to -2.04, P < 0.001). Incretins did not increase the risk of severe hypoglycaemia (odds ratio (OR) 0.83, 95% CI 0.60-1.16, P = 0.287) but increased the occurrence of gastrointestinal side effects (OR 3.46, 95% CI 2.20-5.45, P < 0.001).

CONCLUSIONS

In T1DM patients, GLP-1 RAs, but not DPP-4 inhibitors, combined with insulin appear to be an effective therapy but may increase the occurrence of gastrointestinal side effects.

A randomized clinical trial to evaluate the single-dose pharmacokinetics, pharmacodynamics, and safety of sitagliptin in pediatric patients with type 2 diabetes

OBJECTIVE

To evaluate the single-dose pharmacokinetics (PK), pharmacodynamics (PD), and safety of sitagliptin in pediatric patients with type 2 diabetes mellitus (T2DM).

STUDY DESIGN

This was a randomized, placebo-controlled, double-blind evaluation of sitagliptin in 35 patients 10 to 17 years old with T2DM at 7 clinical research sites. The safety, tolerability, PK, and PD (dipeptidyl peptidase-4 [DPP-4] inhibition and aspects of glucose metabolism) of single doses of 50, 100, and 200 mg were assessed. Appropriate transformations on the PK parameters were used and back-transformed summary statistics are reported.

RESULTS

Adverse experiences were reported by eight study participants; all were of mild intensity except one (intravenous site pain of moderate intensity). PK characteristics in the young patients were comparable to reference adult data, with geometric mean ratios (youths/adults) for AUC_0-∞ , C_max , and C_24hr of 0.82, 1.04, and 0.74, respectively. Single doses of 50, 100, and 200 mg sitagliptin inhibited 67.2%, 73.8%, and 81.2% of plasma DPP-4 activity over 24 hours, respectively. Least squares (LS) mean glucose concentrations 2 hours after an oral glucose tolerance test or a meal tolerance test decreased in study participants treated with sitagliptin, compared to placebo, while active LS mean glucagon-like peptide 1 concentrations increased significantly at all sitagliptin doses in both tests.

CONCLUSIONS

Single doses of sitagliptin as high as 200 mg were generally well tolerated in 10- to 17-year-old male and female study participants with T2DM, and a daily sitagliptin dose of 100 mg is appropriate for evaluation in Phase III safety and efficacy studies in pediatric patients with T2DM. (ClinicalTrials.gov: NCT00730275).

DPP-4 inhibition protects human umbilical vein endothelial cells from hypoxia-induced vascular barrier impairment

Dipeptidyl peptidase-4 (DPP-4) inhibitors are relatively new class of anti-diabetic drugs. Some protective effects of DPP-4 on cardiovascular disease have been described independently from glucose-lowering effect. However, the detailed mechanisms by which DPP-4 inhibitors exert on endothelial cells remain elusive. The purpose of this research was to determine the effects of DPP-4 inhibitor on endothelial barrier function. Human umbilical vein endothelial cells (HUVECs) were cultured and exposed to hypoxia in the presence or absence of Diprotin A, a DPP-4 inhibitor. Immunocytochemistry of vascular endothelial (VE-) cadherin showed that jagged VE-cadherin staining pattern induced by hypoxia was restored by treatment with Diprotin A. The increased level of cleaved β-catenin in response to hypoxia was significantly attenuated by Diprotin A, suggesting that DPP-4 inhibition protects endothelial adherens junctions from hypoxia. Subsequently, we found that Diprotin A inhibited hypoxia-induced translocation of NF-κB from cytoplasm to nucleus through decreasing TNF-α expression level. Furthermore, the tube formation assay showed that Diprotin A significantly restored hypoxia-induced decrease in number of tubes by HUVECs. These results suggest that DPP-4 inhibitior protects HUVECs from hypoxia-induced barrier impairment.

Hypertension and Type 2 Diabetes Are Associated With Decreased Inhibition of Dipeptidyl Peptidase-4 by Sitagliptin

Context

Patients with diabetes often have comorbidities such as hypertension. It is not known how individual characteristics influence response to dipeptidyl peptidase-4 (DPP4) inhibitors.

Objective

We tested the hypothesis that individual characteristics, sitagliptin dose, and genetic variability in DPP4 influence DPP4 activity during sitagliptin.

Design and Setting

Post hoc analysis of clinical and laboratory data from individuals randomized to sitagliptin versus placebo in crossover studies.

Patients and Interventions

Sixty-five subjects [27 with type 2 diabetes mellitus (T2DM) and hypertension, 38 healthy controls] were randomized to 100 mg/d sitagliptin or 200 mg sitagliptin and matching placebo in double-blind, crossover fashion. Fasting blood was obtained at baseline and 60 to 180 minutes after sitagliptin or placebo.

Main Outcome Measures

DPP4 activity and antigen during placebo and sitagliptin and DPP4 inhibition during sitagliptin.

Results

Sitagliptin 100 mg/d was less effective at inhibiting DPP4 activity in individuals with T2DM and hypertension than in healthy controls (P = 0.001, percent inhibition). In healthy controls, 100 mg/d sitagliptin was not as effective as single-dose 200 mg sitagliptin (P = 0.001, percent inhibition). DPP4 genotypes rs2909451 TT (P = 0.02) and rs759717 CC (P = 0.02) were associated with DPP4 activity during sitagliptin. In multivariable analyses, T2DM with hypertension, sitagliptin dose, age, systolic blood pressure, DPP4 activity during placebo, and rs2909451 genotype were significantly associated with DPP4 activity during sitagliptin.

Conclusions

Sitagliptin is less effective in inhibiting DPP4 in individuals with T2DM and hypertension than in healthy controls. Higher doses of DPP4 inhibitors may be required in patients with the metabolic syndrome.

Comparison Between Effectiveness of 100 mg/day Sitagliptin and a Switch to Mitiglinide Calcium Hydrate/Voglibose from 50 mg/day Sitagliptin in Patients with Type 2 Diabetes

We analyzed the effects of 100 mg/day sitagliptin and a switch to mitiglinide calcium hydrate/voglibose compound tablets (MIT/VOG) in patients with type 2 diabetes mellitus (T2DM) treated with 50 mg/day sitagliptin. Five patients with T2DM treated with 50 mg/day sitagliptin and hemoglobin A1c (HbA1c) of ≥6.5% were switched to MIT/VOG, or the dose of sitagliptin was increased to 100 mg/day. The effects of the changes in therapy were compared in a crossover fashion by continuous glucose monitoring. The primary endpoint was mean amplitude of glycemic excursions (MAGE), and the secondary end points were 24-hour mean blood glucose level and mean blood glucose level from 0:00 a.m. to 7:00 a.m. and from 7:00 a.m. to 0:00 a.m., percentage of time with blood glucose level of ≥200 mg/dl and <70 mg/dl, maximum and minimum blood glucose levels, and increases in postprandial blood glucose levels. MAGE was significantly lower with MIT/VOG (P = 0.016), whereas mean blood glucose levels were lower between 0:00 a.m. and 7:00 a.m. with 100 mg/day sitagliptin. The percentage of time with blood glucose level ≥200 mg/dl was significantly shorter with MIT/VOG (P = 0.041). The maximum blood glucose level was significantly lower with MIT/VOG (P = 0.043), and the minimum was significantly lower with 100 mg/day sitagliptin (P = 0.043). Blood glucose levels after dinner and mean increases in postprandial blood glucose levels were significantly lower with MIT/VOG (P = 0.090 and P = 0.045 respectively). In patients with T2DM, treatment with MIT/VOG improves MAGE and postprandial hyperglycemia and 100 mg/day sitagliptin lowers early morning glucose levels. This trial was registered with the University Hospital Medical Information Network (UMIN) (No. UMIN R000008274).

Efficacy and safety of coadministration of sitagliptin with insulin glargine in type 2 diabetes

BACKGROUND

The aim of the randomized present study was to compare the therapeutic efficacy and safety of a combination of sitagliptin, a dipeptidyl peptidase (DPP)-4 inhibitor, plus insulin glargine (GL + sita) with that of premixed insulin aspart 30 (NOV) for type 2 diabetes (T2D) patients controlled with oral hypoglycemic drugs (HbA1c 7 %-9 %).

METHODS

Sixty-five patients were randomized (1:  1) to the GL + sita (n = 33) and NOV (n = 32) groups and were treated with the combination regimen or premixed insulin twice a day for 16 weeks. The primary endpoint was mean change in HbA1c. Secondary endpoints included fasting blood glucose, blood glucose profiles (seven time points), rate of achieving target HbA1c (<7 % or ≤6.5 %), insulin dose, incidence of hypoglycemia, and body weight.

RESULTS

After 16 weeks, there was no significant difference in HbA1c between the two groups, although more patients achieved HbA1c <7.0 % in the GL + sita group. There was a significant difference in body weight changes between the GL + sita and NOV groups (-0.45 vs 1.52 kg, respectively; P < 0.001). Mean plasma glucose and the mean amplitude of glycemic excursion were significantly lower in the GL + sita than NOV group (P < 0.005), as was the incidence of symptomatic hypoglycemia (2.85 % vs. 13.3 %, respectively; P < 0.001).

CONCLUSION

The combination of GL + sita greatly improved HbA1c in T2D patients (HbA1c 7 %-9 %) with an efficacy that was equal to that of premixed insulin. Thus, GL + sita treatment is a viable option for patients who fail to achieve glycemic control using oral hypoglycemic drugs.

Efficacy and safety of once-weekly semaglutide versus once-daily sitagliptin as an add-on to metformin, thiazolidinediones, or both, in patients with type 2 diabetes (SUSTAIN 2): a 56-week, double-blind, phase 3a, randomised trial

BACKGROUND

Semaglutide is a novel glucagon-like peptide-1 (GLP-1) analogue, suitable for once-weekly subcutaneous administration, in development for treatment of type 2 diabetes. We assessed the efficacy and safety of semaglutide versus the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin in patients with type 2 diabetes inadequately controlled on metformin, thiazolidinediones, or both.

METHODS

We did a 56-week, phase 3a, randomised, double-blind, double-dummy, active-controlled, parallel-group, multinational, multicentre trial (SUSTAIN 2) at 128 sites in 18 countries. Eligible patients were aged at least 18 years (or at least 20 years in Japan) and diagnosed with type 2 diabetes, with insufficient glycaemic control (HbA_1c 7·0-10·5% [53·0-91·0 mmol/mol]) despite stable treatment with metformin, thiazolidinediones, or both. We randomly assigned participants (2:2:1:1) using an interactive voice or web response system to 56 weeks of treatment with subcutaneous semaglutide 0·5 mg once weekly plus oral sitagliptin placebo once daily, subcutaneous semaglutide 1·0 mg once weekly plus oral sitagliptin placebo once daily, oral sitagliptin 100 mg once daily plus subcutaneous semaglutide placebo 0·5 mg once weekly, or oral sitagliptin 100 mg once daily plus subcutaneous semaglutide placebo 1·0 mg once weekly. The two oral sitagliptin 100 mg groups (with semaglutide placebo 0·5 mg and 1·0 mg) were pooled for the analyses. The primary endpoint was change in HbA_1c from baseline to week 56, assessed in the modified intention-to-treat population (all randomly assigned participants who received at least one dose of study drug); change in bodyweight from baseline to week 56 was the confirmatory secondary endpoint. Safety endpoints included adverse events and hypoglycaemic episodes. This trial is registered with ClinicalTrials.gov, number NCT01930188.

FINDINGS

Between Dec 2, 2013, and Aug 5, 2015, we randomly assigned 1231 participants; of the 1225 included in the modified intention-to-treat analysis, 409 received semaglutide 0·5 mg, 409 received semaglutide 1·0 mg, and 407 received sitagliptin 100 mg. Mean baseline HbA_1c was 8·1% (SD 0·93); at week 56, HbA_1c was reduced by 1·3% in the semaglutide 0·5 mg group, 1·6% in the semaglutide 1·0 mg group, and 0·5% with sitagliptin (estimated treatment difference vs sitagliptin -0·77% [95% CI -0·92 to -0·62] with semaglutide 0·5 mg and -1·06% [-1·21 to -0·91] with semaglutide 1·0 mg; p<0·0001 for non-inferiority and for superiority, for both semaglutide doses vs sitagliptin). Mean baseline bodyweight was 89·5 kg (SD 20·3); at week 56, bodyweight reduced by 4·3 kg with semaglutide 0·5 mg, 6·1 kg with semaglutide 1·0 mg, and 1·9 kg with sitagliptin (estimated treatment difference vs sitagliptin -2·35 kg [95% CI -3·06 to -1·63] with semaglutide 0·5 mg and -4·20 kg [-4·91 to -3·49] with semaglutide 1·0 mg; p<0·0001 for superiority, for both semaglutide doses vs sitagliptin). The proportion of patients who discontinued treatment because of adverse events was 33 (8%) for semaglutide 0·5 mg, 39 (10%) for semaglutide 1·0 mg, and 12 (3%) for sitagliptin. The most frequently reported adverse events in both semaglutide groups were gastrointestinal in nature: nausea was reported in 73 (18%) who received semaglutide 0·5 mg, 72 (18%) who received semaglutide 1·0 mg, and 30 (7%) who received placebo, and diarrhoea was reported in 54 (13%) who received semaglutide 0·5 mg, 53 (13%) who received semaglutide 1·0 mg, and 29 (7%) who received placebo. Seven (2%) patients in the semaglutide 0·5 mg group, two (<1%) in the semaglutide 1·0 mg group, and five (1%) in the sitagliptin group had blood-glucose confirmed hypoglycaemia. There were six fatal events (two in the semaglutide 0·5 mg group, one in the semaglutide 1·0 mg group, and three in the sitagliptin group); none were considered likely to be related to the trial drugs.

INTERPRETATION

Once-weekly semaglutide was superior to sitagliptin at improving glycaemic control and reducing bodyweight in participants with type 2 diabetes on metformin, thiazolidinediones, or both, and had a similar safety profile to that of other GLP-1 receptor agonists. Semaglutide seems to be an effective add-on treatment option for this patient population.

FUNDING

Novo Nordisk A/S.

Effects of renal impairment on the pharmacokinetics and pharmacodynamics of a novel dipeptidyl peptidase-4 inhibitor, evogliptin (DA-1229)

Evogliptin is a novel potent and selective dipeptidyl peptidase-4 (DPP-4) inhibitor. The aim of the present study was to evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of evogliptin in participants with renal impairment (RI). An open-label, parallel-group clinical study was conducted in participants with mild, moderate and severe RI and in matched participants with normal renal function (NRF). A single oral 5-mg dose of evogliptin was administered and serial blood and urine samples were obtained to assess the PK and PD characteristics of evogliptin. Baseline urine samples were collected to evaluate endogenous CYP3A metabolic markers. The plasma exposure to evogliptin and degree of DPP-4 activity inhibition increased with decreasing renal function. The mean areas under the concentration-time curves from 0 to 120 hours were increased 1.2-, 1.8- and 1.98-fold in the mild, moderate and severe RI groups, respectively, compared with the NRF group. The levels of CYP3A metabolic markers were lower in the RI group than in the NRF group. The increase in the plasma concentration of evogliptin is unlikely to result in changes in its efficacy or safety, considering the results of previous clinical studies.

The Glucose-lowering Efficacy of Sitagliptin in Obese Japanese Patients with Type 2 Diabetes

Objective Dipeptidyl peptidase-4 (DPP-4) inhibitors are the most frequently prescribed oral hypoglycemic agents in Japan. Although a relationship between the efficacy of DPP-4 inhibitors and the body mass index (BMI) has been reported, this relationship is controversial. We investigated whether the BMI value affects the glucose-lowering efficacy of sitagliptin in obese Japanese patients with type 2 diabetes. Methods One hundred sixty-two outpatients with inadequate glycemic control were divided into four groups based on their baseline BMI values. They were then treated with sitagliptin (a DPP-4 inhibitor) for 3 months and followed-up for 12 months. Results Sitagliptin significantly reduced the hemoglobin A1c level (HbA1c: -0.71±0.55%) after 3 months, and continued to reduce the HbA1c level until 12 months. There was no significant difference in the efficacy of sitagliptin among the four BMI groups. A multiple linear regression analysis indicated that the factors contributing to the change in the HbA1c level were the baseline level of HbA1c and the homeostasis model assessment of β-cell function (HOMA-β). In terms of the relationship between the baseline BMI value and the efficacy of sitagliptin treatment, the number of patients who responded to sitagliptin treatment after 3 months was lowest in the group of patients with the highest BMI values. A multiple logistic regression analysis revealed that the baseline HOMA-β function and HbA1c level and a baseline BMI value of ≥30 kg/m² significantly contributed to the response to sitagliptin treatment. Conclusion The results indicated that sitagliptin treatment was effective in controlling glucose metabolism disorder in obese Japanese patients with type 2 diabetes. However, the efficacy of sitagliptin treatment might be attenuated in severely obese patients, such as those with a BMI value of ≥30 kg/m².

Effects of alogliptin on the ratio of glycated albumin to HbA1c in patients with type 2 diabetes mellitus

The ratio of glycated albumin (GA) to HbA1c (the GA/HbA1c ratio) has been used as a glycemic control indicator that reflects postprandial plasma glucose levels or glycemic variability. In this study, we investigated the effects of alogliptin, a DPP-4 inhibitor, on the GA/HbA1c ratio in patients with type 2 diabetes mellitus. Thirty-eight patients with type 2 diabetes mellitus whose glycemic control was stable were enrolled, and alogliptin (12.5 or 25 mg/day) was then administered to them for 24 weeks. HbA1c and GA levels both significantly decreased after 24 weeks (P < 0.0001), whereas the GA/HbA1c ratio did not (P = 0.129). No correlation was observed between the change in the GA/HbA1c ratio (the ΔGA/HbA1c ratio) and HbA1c or GA level before the administration of alogliptin; however, a negative correlation was found between the ΔGA/HbA1c ratio and the GA/HbA1c ratio before the administration of alogliptin (R = -0.322, P = 0.049). Although the GA/HbA1c ratio in the low-value group (<2.80) was not significantly affected by the administration of alogliptin, that in the high-value group (≥2.80) significantly decreased (P = 0.008). The administration of alogliptin significantly decreased the GA/HbA1c ratio in the high-value group after 24 weeks. Alogliptin may be more useful for patients with high postprandial plasma glucose levels than in those with low postplandial plasma glucose levels.

DPP-4 Inhibition by Linagliptin Attenuates Obesity-Related Inflammation and Insulin Resistance by Regulating M1/M2 Macrophage Polarization

Dipeptidyl peptidase 4 (DPP-4) cleaves a large number of chemokine and peptide hormones involved in the regulation of the immune system. Additionally, DPP-4 may also be involved in macrophage-mediated inflammation and insulin resistance. Thus, the current study investigated the effect of linagliptin, an inhibitor of DPP-4, on macrophage migration and polarization in white adipose tissue (WAT) and liver of high-fat diet-induced obese (DIO) mice. DPP-4(+) macrophages in lean and obese mice were quantified by fluorescence-activated cell sorting (FACS) analysis. DPP-4 was predominantly expressed in F4/80(+) macrophages in crown-like structures compared with adipocytes in WAT of DIO mice. FACS analysis also revealed that, compared with chow-fed mice, DIO mice exhibited a significant increase in DPP-4(+) expression in cells within adipose tissue macrophages (ATMs), particularly M1 ATMs. Linagliptin showed a greater DPP-4 inhibition and antioxidative capacity than sitagliptin and reduced M1-polarized macrophage migration while inducing an M2-dominant shift of macrophages within WAT and liver, thereby attenuating obesity-induced inflammation and insulin resistance. Loss of macrophage inflammatory protein-1α, a chemokine and DPP-4 substrate, in DIO mice abrogated M2 macrophage-polarizing and insulin-sensitizing effects of linagliptin. Therefore, the inhibition of DPP-4 by linagliptin reduced obesity-related insulin resistance and inflammation by regulating M1/M2 macrophage status.

Effect of Acarbose, Sitagliptin and combination therapy on blood glucose, insulin, and incretin hormone concentrations in experimentally induced postprandial hyperglycemia of healthy cats

Acarbose (AC) and Sitagliptin (STGP) are oral hypoglycemic agents currently used either alone or in conjunction with human diabetic (Type 2) patients. AC has been used with diabetic cats, but not STGP thus far. Therefore, the objective of this study was to determine the potential use of AC or STGP alone and in combination for diabetic cats, by observing their effect on short-term post-prandial serum glucose, insulin, and incretin hormone (active glucagon-like peptide-1 (GLP-1) and total glucose dependent insulinotropic polypeptide (GIP)) concentrations in five healthy cats, following ingestion of a meal with maltose. All treatments tended (p<0.10; 5-7.5% reduction) to reduce postprandial glucose area under the curve (AUC), with an accompanying significant reduction (p<0.05, 35-45%) in postprandial insulin AUC as compared to no treatment. Meanwhile, a significant increase (p<0.05) in postprandial active GLP-1 AUC was observed with STGP (100% higher) and combined treatment (130% greater), as compared to either AC or no treatment. Lastly, a significant reduction (p<0.05) in postprandial total GIP AUC was observed with STGP (21% reduction) and combined treatment (7% reduction) as compared to control. Overall, AC, STGP, or combined treatment can significantly induce positive post-prandial changes to insulin and incretin hormone levels of healthy cats. Increasing active GLP-1 and reducing postprandial hyperglycemia appear to be the principal mechanisms of combined treatment. Considering the different, but complementary mechanisms of action by which AC and STGP induce lower glucose and insulin levels, combination therapy with both these agents offers great potential for treating diabetic cats in the future.

Comparisons of the efficacy of glucose control, lipid profile, and β-cell function between DPP-4 inhibitors and AGI treatment in type 2 diabetes patients: a meta-analysis

The aim of this study is to compare the efficacy of dipeptidyl peptidase-4 (DPP-4) inhibitor treatment with α-glucosidase inhibitor (AGI) treatment in patients with type 2 diabetes through a meta-analysis. Studies were identified by a literature search of Medline, Embase, and others from the time that recording commenced until December 2014. The meta-analysis was performed by computing the weighted mean difference (WMD) and 95 % confidence interval (CI) for a change from baseline to the study endpoint for DPP-4 inhibitors versus AGIs. Nine randomized controlled trial were judged to be appropriate for inclusion in the meta-analysis. One thousand and forty-six patients were treated with a DPP-4 inhibitor, while 929 patients were treated with AGI treatment; the groups had a comparable baseline body mass index of 25.5 ± 1.3 kg/m(2) and mean baseline HbA1c of 7.83 ± 0.53 %. Treatment with DPP-4 inhibitors led to a significantly greater change from baseline in the HbA1c levels (WMD -0.30 %; 95 % CI -0.47 to -0.13 %, p < 0.001) and fasting plasma glucose levels (WMD -0.50 mmol/L; 95 % CI -0.89 to -0.11 mmol/L, p = 0.01) compared with AGI treatment. Compared with AGIs, treatment with DPP-4 inhibitors was associated with a significantly greater increase in the weight change from baseline (WMD 0.89 kg; 95 % CI 0.53-1.25, p < 0.001). Treatment with DPP-4 inhibitors was associated with a significantly greater increase in the fasting insulin level from baseline (WMD 0.63 µU/mL; 95 % CI 0.35-0.90 µU/mL, p < 0.001). DPP-4 inhibitors significantly improved homeostatic model assessment for β-cell function in type 2 diabetes patients compared with AGI treatment (WMD 5.43; 95 % CI 1.01-9.85, p = 0.02). DPP-4 inhibitors were associated with a significantly greater decrease in the cholesterol (CHO) level (WMD -0.19 mmol/L; 95 % CI -0.19 to -0.19 mmol/L, p < 0.001) and a significantly greater decrease in the low-density lipoprotein cholesterol (LDL-C) level (WMD -0.16 mmol/L; 95 % CI -0.26 to -0.05 mmol/L, p = 0.003). Compared with AGIs (813 participants), treatment with DPP-4 inhibitors (1031 participants) was associated with a significantly lower incidence of drug-related adverse event (OR 0.48; 95 % CI 0.36-0.64, p < 0.0001). The efficacy of glucose control and improvement of β-cell function, as well as total CHO and LDL-C decreases, in DPP-4 inhibitor treatment were superior to those with AGI treatment, and there was a lower incidence of drug-related AE.

Multiplexed Quantification of Proglucagon-Derived Peptides by Immunoaffinity Enrichment and Tandem Mass Spectrometry after a Meal Tolerance Test

BACKGROUND

Proglucagon-derived peptides (PGDPs), which include glucagon-like peptide (GLP)-1, glucagon, and oxyntomodulin, are key regulators of glucose homeostasis and satiety. These peptide hormones are typically measured with immuno-based assays (e.g., ELISA, RIA), which often suffer from issues of selectivity.

METHODS

We developed a multiplexed assay for measuring PGDPs including GLP-1 (7-36) amide, GLP-1 (9-36) amide, glucagon, and oxyntomodulin by mass spectrometry and used this assay to examine the effect of a meal tolerance test on circulating concentrations of these hormones. Participants fasted overnight and were either given a meal (n = 8) or continued to fast (n = 4), with multiple blood collections over the course of 3 h. Plasma samples were analyzed by microflow immunoaffinity (IA)-LC-MS/MS with an isotope dilution strategy.

RESULTS

Assay performance characteristics were examined and established during analytical validation for all peptides. Intra- and interassay imprecision were found to be 2.2%-10.7% and 6.8%-22.5%, respectively. Spike recovery was >76%, and dilution linearity was established up to a 16-fold dilution. Immediately after the meal tolerance test, GLP-1 and oxyntomodulin concentrations increased and had an almost identical temporal relationship, and glucagon concentrations increased with a slight delay.

CONCLUSIONS

IA-LC-MS/MS was used for the simultaneous and selective measurement of PGDPs. This work includes the first indication of the physiological concentrations and modulation of oxyntomodulin after a meal.

Antidiabetic treatment with gliptins: focus on cardiovascular effects and outcomes

The traditional oral pharmacological therapy for type 2 diabetes mellitus (T2DM) has been based on the prescription of metformin, a biguanide, as first line antihyperglycemic agent world over. It has been demonstrated that after 3 years of treatment, approximately 50 % of diabetic patients could achieve acceptable glucose levels with monotherapy; but by 9 years this had declined to only 25 %. Therefore, the implementation of a combined pharmacological therapy acting via different pathways becomes necessary, and its combination with a compound of the sulfonylurea group was along decades the most frequently employed prescription in routine clinical practice. Meglitinides, glitazones and alpha-glucosidase inhibitors were subsequently developed, but the five mentioned groups of oral antihyperglycemic agents are associated with variable degrees of undesirable or even severe cardiovascular events. The gliptins—also called dipeptidyl peptidase 4 (DPP4) inhibitors—are an additional group of antidiabetic compounds with increasing clinical use. We review the status of the gliptins with emphasis on their capabilities to positively or negatively affect the cardiovascular system, and their potential involvement in major adverse cardiovascular events (MACE). Alogliptin, anagliptin, linagliptin, saxagliptin, sitagliptin, teneligliptin and vildagliptin are the compounds currently in clinical use. Regardless differences in chemical structure and metabolic pathways, gliptins as a group exert favorable changes in experimental models. These changes, as an almost general rule, include improved endothelial function, reduction of inflammatory markers, oxidative stress ischemia/reperfusion injury and atherogenesis. In addition, increased adiponectin levels and modest decreases in lipidemia and blood pressure were reported. In clinical settings, several trials—notably the longer one, employing sitagliptin, with a mean follow-up period of 3 years—did not show an increased risk for ischemic events. Anyway, it should be emphasized that the encouraging results from basic science were not yet translated into clinical evidence, probably due the multiple and pleiotropic enzymatic effects of DPP4 inhibition. Moreover, when employing saxagliptin, while the drug was not associated with an augmented risk for ischemic events, it should be pinpointed that the rate of hospitalization for heart failure was significantly increased. Gliptins as a group constitute a widely accepted therapy for the management of T2DM, usually as a second-line medication. Nonetheless, for the time being, a definite relationship between gliptins treatment and improved cardiovascular outcomes remains uncertain and needs yet to be proven.

Four-Year Durability of Initial Combination Therapy with Sitagliptin and Metformin in Patients with Type 2 Diabetes in Clinical Practice; COSMIC Study

OBJECTIVES

We investigated the efficacy of initial combination therapy with sitagliptin and metformin in patients with type 2 diabetes for 4 years in clinical practice.

METHODS

Between 2009 and 2010, we reviewed 1,178 patients with type 2 diabetes (HbA1c ≥7.5% or 58 mmol/mol) prescribed initial combination therapy with sitagliptin and metformin. After excluding 288 patients without a second follow-up, 890 individuals (age, 58.0 ± 12.5 years; BMI, 25.4 ± 3.5 kg/m2; HbA1c, 8.6 ± 1.1%) were followed up with every 3-6 months for 4 years. Homeostasis model assessments for insulin resistance and β-cell function (HOMA-β) were recorded at baseline. The response criterion was HbA1c reduction by ≥0.8% from baseline or attainment of the target HbA1c (≤7.0% or 53 mmol/mol). At the end of every year of treatment, changes in HbA1c from the baseline were assessed.

RESULTS

After 1 year, 72.2% of patients with initial combination therapy had responded, defined as HbA1c reduction ≥0.8% or attainment of the target HbA1c ≤7.0%. After 4 years, 35.4% of the patients still showed a response, with an HbA1c level of 7.0 ± 0.9%. A high HbA1c level at baseline was the most significant independent predictor of the long-term response (P<0.001). In addition, low HOMA-β was a significant predictor of a greater reduction in HbA1c. This treatment was generally well tolerated over the 4-year follow-up period, without any serious adverse events.

CONCLUSIONS

This real-world follow-up study shows a persistent glucose-reducing effect of initial combination therapy with sitagliptin and metformin for up to 4 years.

A comparison of glycaemic effects of sitagliptin and sulfonylureas in elderly patients with type 2 diabetes mellitus

INTRODUCTION

In the USA, 45% of patients with type 2 diabetes mellitus (T2DM) are elderly (≥ 65 years old). In general, use of sulfonylurea increases with patient age as does the associated risk for hypoglycaemia, and the consequences of hypoglycaemia can be more pronounced in elderly patients. Sitagliptin, a DPP-4 inhibitor, improves glycaemic control in adult patients of all ages with T2DM, with a low risk of hypoglycaemia when used alone or in combination with other antidiabetic agents that are not generally associated with hypoglycaemia when used independently.

METHODS

In a post hoc analysis, pooled data from elderly patients who participated in one of three double-blind studies comparing the effects of therapy with sitagliptin (100 mg/day) vs. sulfonylurea (in titrated doses) were analysed for changes from baseline in HbA1c, fasting plasma glucose (FPG), and body weight and for the incidence of reported symptomatic hypoglycaemia. In these studies, patients on diet alone or metformin were randomised to sitagliptin or glipizide for 104 weeks (studies 1 and 2) or glimepiride for 30 weeks (study 3). The analysis included 372 elderly patients who completed a trial through 25 or 30 weeks.

RESULTS

Both HbA1c and FPG decreased from baseline with each treatment, with no statistically significant differences between treatments. A significantly lower incidence of reported hypoglycaemia was observed with sitagliptin compared with sulfonylurea (6.2% vs. 27.8%; p < 0.001). Body weight decreased significantly with sitagliptin but not with sulfonylurea. Significantly more patients on sitagliptin than on sulfonylureas achieved a composite end-point of >0.5% HbA1c reduction with no reported hypoglycaemia or increase in body weight (44.1% vs. 16.0%; p < 0.001).

CONCLUSION

In this analysis of elderly patients with T2DM, compared with sulfonylurea, sitagliptin provided similar glycaemic efficacy with less hypoglycaemia and with body weight loss.

Practical, asymmetric route to sitagliptin and derivatives: development and origin of diastereoselectivity

The development of a practical and scalable process for the asymmetric synthesis of sitagliptin is reported. Density functional theory calculations reveal that two noncovalent interactions are responsible for the high diastereoselection. The first is an intramolecular hydrogen bond between the enamide NH and the boryl mesylate S═O, consistent with MsOH being crucial for high selectivity. The second is a novel C-H···F interaction between the aryl C5-fluoride and the methyl of the mesylate ligand.

Synthesis of New DPP-4 Inhibitors Based on a Novel Tricyclic Scaffold

A novel molecular scaffold has been synthesized, and its synthesis and incorporation into new analogues of biologically active molecules will be discussed. A comparison of the inhibitory activity of these compounds to the known type-2 diabetes compound (sitagliptin) against dipeptidyl peptidase-4 (DPP-4) will be shown.

Comparison of treatment with sitagliptin or sulfonylurea in patients with type 2 diabetes mellitus and mild renal impairment: a post hoc analysis of clinical trials

INTRODUCTION

Impaired renal function is a major complication of type 2 diabetes mellitus (T2DM). Mild renal impairment is present in 38% of patients with T2DM and may impact choice of antihyperglycemic agent. Sulfonylureas and dipeptidyl peptidase-4 (DPP-4) inhibitors are commonly used to treat hyperglycemia in patients with T2DM and renal impairment. Although in general sulfonylurea use is associated with an increased risk of hypoglycemia and weight gain, while DPP-4 inhibitor use is associated with a low risk of hypoglycemia, and is weight neutral, the relative efficacy and tolerability of these agents in patients with mild renal impairment has not been evaluated.

METHODS

In a post hoc analysis, data from 1,211 subjects with T2DM and mild renal impairment (estimated glomerular filtration rates of 60 to <90 mL/min/1.73 m(2)), who completed 25 or 30 weeks of one of three double-blind clinical trials comparing the DPP-4 inhibitor sitagliptin 100 mg/day with sulfonylureas in titrated doses, were pooled. The analysis compared change from baseline in glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), body weight, incidence of symptomatic hypoglycemia and the percentages of subjects meeting a composite endpoint of HbA1c decrease >0.5% without symptomatic hypoglycemia or body weight gain between sitagliptin and sulfonylurea treatment groups.

RESULTS

HbA1c and FPG decreased similarly with sitagliptin or sulfonylurea. A lower incidence of hypoglycemia was observed with sitagliptin. Body weight decreased with sitagliptin but increased with sulfonylurea. A greater percentage of subjects treated with sitagliptin (41.1%) than treated with sulfonylurea (16.9%) achieved the composite endpoint of >0.5% HbA1c reduction with no symptomatic hypoglycemia or body weight gain.

CONCLUSION

In this analysis of subjects with T2DM and mild renal impairment, treatment with sitagliptin provided glycemic efficacy similar to sulfonylurea, with less hypoglycemia and with body weight loss compared to body weight gain seen with sulfonylurea.

TRIAL REGISTRATIONS

ClinicalTrials.gov #NCT00482079, #NCT00094770, #NCT00701090.

Green chemistry approaches as sustainable alternatives to conventional strategies in the pharmaceutical industry

Green chemistry is a rapidly developing field for the sustainable development of future science and technology. Incorporating green chemistry into the synthesis of active pharmaceutical ingredients and intermediates is of ongoing importance to the pharmaceutical industry.

The durability of sitagliptin in elderly patients with type 2 diabetes

AIM

To evaluate the durability of sitagliptin and to assess changes in clinical chronic complications following sitagliptin monotherapy for 48 months in elderly patients with type 2 diabetes mellitus (T2DM).

SUBJECTS AND METHODS

We enrolled 76 drug-naïve patients (40 women and 36 men; mean age: 71.3±11.7 years) with T2DM who received 25-100 mg of sitagliptin therapy from an outpatient clinic. The observational period for each patient was >48 months, beginning at the time sitagliptin therapy was initiated. The following were measured or performed at the beginning of each year: body mass index; serum total cholesterol, low-density lipoprotein, high-density lipoprotein; triglyceride levels; creatinine (Cr) levels; urine albumin and urine Cr; nonmydriatic fundusgraphy; and semiquantified neuropathy. The fasting plasma glucose and glycated hemoglobin (HbA1c) was measured every 3-6 months.

RESULTS

The change in HbA1c was significantly reduced after 6 months of therapy (7.1%±0.8% to 6.3%±0.2%). No changes in fasting plasma glucose, Cr, serum total cholesterol, triglyceride, low-density lipoprotein, high-density lipoprotein, body mass index, and microvascular complications were apparent. Using repeated measures to test the sequential changes in HbA1c from month 6 to month 48, the test of within-subjects effect was not significant (P=0.34).

CONCLUSION

Sitagliptin has a durable effect and stabilizes microvascular complication progression in elderly patients. This study can provide useful data for clinicians and health care professionals using sitagliptin monotherapy in the treatment of elderly patients with T2DM.