Novel sulfonylurea and non-sulfonylurea drugs to promote the secretion of insulin

Emerging Perspectives on the Impact of Diabetes Mellitus and Anti-Diabetic Drugs on Premenstrual Syndrome. A Narrative Review

Diabetes mellitus (DM) and premenstrual syndrome (PMS) are global health challenges. Both disorders are often linked to a range of physical and psychological symptoms that significantly impact the quality of life of many women. Yet, the exact relation between DM and PMS is not clear, and the management of both conditions poses a considerable challenge. In this review, we aimed to investigate the interplay between DM, anti-diabetic drugs, and the different theories and symptoms of PMS. Female sex hormones are implicated in the pathophysiology of PMS and can also impair blood glucose control. In addition, patients with diabetes face a higher susceptibility to anxiety and depression disorders, with a significant number of patients experiencing symptoms such as fatigue and difficulty concentrating, which are reported in patients with PMS as well. Complications related to diabetic medications, such as hypoglycemia (with sulfonylurea) and fluid retention (with thiazolidinediones) may also mediate PMS-like symptoms. DM can, in addition, disturb the normal gut microbiota (GM), with a consequent loss of beneficial GM metabolites that guard against PMS, particularly the short-chain fatty acids and serotonin. Among the several available anti-diabetic drugs, those (1) with an anti-inflammatory potential, (2) that can preserve the beneficial GM, and (3) possessing a lower risk for hypoglycemia, might have a favorable outcome in PMS women. Yet, well-designed clinical trials are needed to investigate the anti-diabetic drug(s) of choice for patients with diabetes and PMS.

A Review on Experimental Models to Test Medicinal Plants on Postprandial Blood Glucose in Diabetes

Due to the gravity of postprandial hyperglycemia in the development of microvascular and macrovascular diseases in diabetics, many medicinal plants are tested to determine their effectiveness in glycemic control and the mechanisms of action of the products. Consequently, various diabetic models have been developed and enhanced over the years. The objective of this review is to describe some of the experimental models to study the effect of medicinal plants used to control postprandial hyperglycemia. Data was collected from PubMed, ScienceDirect, Scopus, and Google scholar (1953-2021). Fiftyseven (57) studies were included in this review article. Ten models were identified and described. For each model, we described the targets involved and their roles in postprandial blood glucose control. The experimental design and procedures described the targets such as an α-glucosidase enzyme, SGLT1, GLUT2, DPP-IV, Na+/K+ ATPase pump, or intestinal motility in the models, experiment design and procedures were described. This review will facilitate the selection of the most appropriate model for studying agents used to investigate postprandial blood glucose.

Bioactive Compounds in Anti-Diabetic Plants: From Herbal Medicine to Modern Drug Discovery

Natural products, including organisms (plants, animals, or microorganisms) have been shown to possess health benefits for animals and humans. According to the estimation of the World Health Organization, in developing countries, 80% of the population has still depended on traditional medicines or folk medicines which are mostly prepared from the plant for prevention or treatment diseases. Traditional medicine from plant extracts has proved to be more affordable, clinically effective and relatively less adverse effects than modern drugs. Literature shows that the attention on the application of phytochemical constituents of medicinal plants in the pharmaceutical industry has increased significantly. Plant-derived secondary metabolites are small molecules or macromolecules biosynthesized in plants including steroids, alkaloids, phenolic, lignans, carbohydrates and glycosides, etc. that possess a diversity of biological properties beneficial to humans, such as their antiallergic, anticancer, antimicrobial, anti-inflammatory, antidiabetic and antioxidant activities Diabetes mellitus is a chronic disease result of metabolic disorders in pancreas β-cells that have hyperglycemia. Hyperglycemia can be caused by a deficiency of insulin production by pancreatic (Type 1 diabetes mellitus) or insufficiency of insulin production in the face of insulin resistance (Type 2 diabetes mellitus). The current medications of diabetes mellitus focus on controlling and lowering blood glucose levels in the vessel to a normal level. However, most modern drugs have many side effects causing some serious medical problems during a period of treating. Therefore, traditional medicines have been used for a long time and play an important role as alternative medicines. Moreover, during the past few years, some of the new bioactive drugs isolated from plants showed antidiabetic activity with more efficacy than oral hypoglycemic agents used in clinical therapy. Traditional medicine performed a good clinical practice and is showing a bright future in the therapy of diabetes mellitus. World Health Organization has pointed out this prevention of diabetes and its complications is not only a major challenge for the future, but essential if health for all is to be attained. Therefore, this paper briefly reviews active compounds, and pharmacological effects of some popular plants which have been widely used in diabetic treatment. Morphological data from V-herb database of each species was also included for plant identification.

Effects of nateglinide and repaglinide administered intracerebroventricularly on the CA3 hippocampal neuronal cell death and hyperglycemia induced by kainic acid in mice

Meglitinides (nateglinide and repaglinide) are widely used oral drugs for the treatment of type II diabetes mellitus. In the present study, the effects of meglinitides administered supraspinally on kainic acid (KA)-induced hippocampal neuronal cell death and hyperglycemia were studied in ICR mice. Mice were pretreated intracerebroventricularly (i.c.v.) with 30 μg of nateglinide and repaglinide for 10 min and then, mice were administered i.c.v. with KA (0.1 μg). The neuronal cell death in the CA3 region in the hippocampus was assessed 24h after KA administration and the blood glucose level was measured 30, 60, and 120 min after KA administration. We found that i.c.v. pretreatment with repaglinide attenuated the KA-induced neuronal cell death in CA3 region of the hippocampus and hyperglycemia. However, nateglinide pretreated i.c.v. did not affect the KA-induced neuronal cell death and hyperglycemia. In addition, KA administered i.c.v. caused an elevation of plasma corticosterone level and a reduction of the plasma insulin level. Furthermore, i.c.v. pretreatment with repaglinide attenuated KA-induced up-regulation of plasma corticosterone level. Furthermore, i.c.v. administration of repaglinide alone increased plasma insulin level and repaglinide pretreated i.c.v. caused a reversal of KA-induced hypoinsulinemic effect. Our results suggest that supraspinally administered repaglinide, but not nateglinide, exerts a protective effect against the KA-induced neuronal cells death in CA3 region of the hippocampus. The neuroprotective effect of repaglinide appears to be mediated by lowering the blood glucose level induced by KA.

New player on an old field; the keap1/Nrf2 pathway as a target for treatment of type 2 diabetes and metabolic syndrome

Nuclear erythroid factor 2 like 2 (Nrf2) has been described as a transcription factor that serves as a master regulator of the adaptive response to exogenous and endogenous oxidative and electrophilic stresses. Evidence of Nrf2 crosstalk with other molecular pathways is increasing; recent publications have proposed a role of Nrf2 in the development of obesity and in the highly regulated process of adipocyte differentiation through its interaction with other transcription factors and receptors implicated in metabolic regulation. In the present review, we discuss the available data on the possible role of Nrf2 in obesity and metabolic syndrome and the feasibility of using Nrf2 as a therapeutic target in the clinical setting.

Differential immunolocalization of sulfonylurea receptors in mouse and rat ureters

The receptors for sulphonylurea (SURs) are known to be expressed in the mouse kidney, but their expression in the ureter is undefined. Owing to the physiological and pharmacological significance of SURs, the localization of SUR in ureters of adult mice and rats was investigated through immunohistochemistry. Animals were perfused transcardially with 4% paraformaldehyde and tissues were processed for immunohistochemistry using polyclonal antisera against SUR2A and SUR2B (SUR1) receptor proteins. Sections were incubated with primary and secondary antisera and developed with aminoethylcarbazole as a chromogen. A differentiated localized staining pattern of SUR proteins in rat and mouse ureters is demonstrated. In the mouse, immunoreactivity of SUR2A was predominantly confined to the cytoplasmic portion of epithelial cells and blood vessels, with comparatively low-level staining found in smooth muscle. In contrast, SUR2B (SUR1) immunoreactivity was absent in mouse ureters. In rats, SUR2A immunoreactivity was localized only in the blood vessels, while SUR2B (SUR1) immunoreactivity was localized in the epithelial cell cytoplasm. Tissue specificity of SUR is demonstrated in the two species of rodents and suggests a role of SUR proteins in urinary metabolism pertaining possibly to salt handling and maintenance of the smooth muscle tone.

Novel sulfonylurea derivatives as H3 receptor antagonists. Preliminary SAR studies

The combination of antagonism at histamine H(3) receptor and the stimulation of insulin secretion have been proposed as an approach to new dual therapeutic agents for the treatment of type 2 diabetes mellitus associated with obesity. We have designed and synthesized a new series of non-imidazole derivatives, based on a basic amine ring connected through an alkyl spacer of variable length to a phenoxysulfonylurea moiety. These compounds were initially evaluated for histamine H(3) receptor binding affinities, suggesting that a propoxy chain linker between the amine and the core ring could be essential for optimal binding affinity. Compound 56, 1-(naphthalen-1-yl)-3-[(p-(3-pyrrolidin-1-ylpropoxy)benzene)]sulfonylurea exhibited the best H(3) antagonism affinity. However, since all these derivatives failed to block K(ATP) channels, the link of these two related moieties should not be considered a good pharmacophore for obtaining new dual H(3) antagonists with insulinotropic activity, suggesting the necessity to propose a new chemical hybrid prototype.

Advances in the treatment of type 2 diabetes mellitus

There is a rising worldwide prevalence of diabetes, especially type 2 diabetes mellitus (T2DM), which is one of the most challenging health problems in the 21st century. The associated complications of diabetes, such as cardiovascular disease, peripheral vascular disease, stroke, diabetic neuropathy, amputations, renal failure, and blindness result in increasing disability, reduced life expectancy, and enormous health costs. T2DM is a polygenic disease characterized by multiple defects in insulin action in tissues and defects in pancreatic insulin secretion, which eventually leads to loss of pancreatic insulin-secreting cells. The treatment goals for T2DM patients are effective control of blood glucose, blood pressure, and lipids (if elevated) and, ultimately, to avert the serious complications associated with sustained tissue exposure to excessively high glucose concentrations. Prevention and control of diabetes with diet, weight control, and physical activity has been difficult. Treatment of T2DM has centered on increasing insulin levels, either by direct insulin administration or oral agents that promote insulin secretion, improving sensitivity to insulin in tissues, or reducing the rate of carbohydrate absorption from the gastrointestinal tract. This review presents comprehensive and up-to-date information on the mechanism(s) of action, efficacy, pharmacokinetics, pleiotropic effects, drug interactions, and adverse effects of the newer antidiabetic drugs, including (1) peroxisome proliferator-activated-receptor-γ agonists (thiazolidinediones, pioglitazone, and rosiglitazone); (2) the incretin, glucagon-like peptide-) receptor agonists (incretin-mimetics, exenatide. and liraglutide), (3) inhibitors of dipeptidyl-peptidase-4 (incretin enhancers, sitagliptin, and vildagliptin), (4) short-acting, nonsulfonylurea secretagogue, meglitinides (repaglinide and nateglinide), (5) amylin anlog-pramlintide, (6) α-glucosidase inhibitors (miglitol and voglibose), and (7) colesevelam (a bile acid sequestrant). In addition, information is presented on drug candidates in clinical trials, experimental compounds, and some plants used in the traditional treatment of diabetes based on experimental evidence. In the opinion of this reviewer, therapy based on orally active incretins and incretin mimetics with long duration of action that will be efficacious, preserve the β-cell number/function, and block the progression of diabetes will be highly desirable. However, major changes in lifestyle factors such as diet and, especially, exercise will also be needed if the growing burden of diabetes is to be contained.

Effects of repaglinide on oxidative stress in tissues of diabetic rabbits

In this study, the antioxidative properties of repaglinide were examined in tissues of alloxan-induced diabetic rabbits. Glutathione (GSH), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R) and protein carbonyl groups (PCG) were measured after 4 and 8 weeks treatment with repaglinide (0.3 mg/kg daily). In liver, diabetic versus control values (mean +/- S.E.M., p<0.05) for GSH-Px were 181.0 +/- 5.4 mU/mg protein versus 203.1 +/- 1.9 mU/mg protein and 187.4 +/- 6.6 mU/mg protein versus 240.9 +/- 18.8 mU/mg protein. The respective values for GSH were 33.7 +/- 0.4 nmol/mg protein versus 49.0 +/- 1.6 nmol/mg protein and 37.7 +/- 1.0 nmol/mg protein versus 41.2 +/- 0.7 nmol/mg protein. In diabetic kidney, GSSG-R activity (20.6 +/- 1.6 mU/mg protein versus 32.4 +/- 1.5 mU/mg protein and 23.6 +/- 0.6 mU/mg protein versus 36.3 +/- 0.3 mU/mg protein) and GSH level (16.6 +/- 0.5 nmol/mg protein versus 23.2 +/- 0.9 nmol/mg protein and 17.9 +/- 0.5 nmol/mg protein versus 23.2 +/- 0.6 nmol/mg protein) were reduced compared to control. PCG level was elevated in diabetic liver (0.58 +/- 0.02 nmol/mg protein versus 0.16 +/- 0.03 nmol/mg protein at 4 weeks and 0.64 +/- 0.04 nmol/mg protein versus 0.16 +/- 0.03 nmol/mg protein at 8 weeks) and in diabetic kidney (0.32 +/- 0.03 nmol/mg protein versus 0.11 +/- 0.02 nmol/mg protein and 0.35 +/- 0.03 nmol/mg protein versus 0.16 +/- 0.03 nmol/mg protein). Repaglinide did not affect the glucose level but reduced to some extent the oxidative stress enhanced by chronic hyperglycemia. In diabetic kidney, it restored to control values GSSG-R activity (45.4 +/- 2.0 mU/mg protein at 4 weeks and 41.1 +/- 0.07 mU/mg protein at 8 weeks), GSH level (27.0 +/- 0.8 and 26.8 +/- 0.9 nmol/mg protein), and partly PCG level (0.17 +/- 0.02 nmol/mg protein at 8 weeks). The treatment partly affected GSH-Px activity (262.7 +/- 17.6 mU/mg protein) and GSH level (40.4 +/- 1.4 nmol/mg protein) in diabetic liver. This study shows that repaglinide produces measurable antioxidative effects at therapeutic dose.

Role of insulin secretagogues and insulin sensitizing agents in the prevention of cardiovascular disease in patients who have diabetes

In the absence of clinical trial evidence to compare the secretagogues with sensitizers, it is difficult to make recommendations about which class of drug is more important to prescribe for the prevention of cardiovascular disease in diabetes mellitus. Epidemiologic data supports insulin resistance as a major factor in cardiovascular disease through a variety of mechanisms. Because sensitizers improve insulin sensitivity and correct many of the vascular abnormalities that are associated with insulin resistance, it is tempting to suggest that they may be superior for this purpose. Conversely, meeting the goals that are recommended for glycemia also are important and achieving them may not be always possible with sensitizers, particularly in the later stages of the disease when insulin levels are not high,despite insulin resistance. In such situations,combination therapy may be needed with both types of drugs. No data are available on the cardiovascular effects of such combinations;some retrospective data suggest a possibility of increased events with the combination of sulfonylureas and metformin. Thus, further prospective studies in this area are necessary.

The impact of antidiabetic therapies on cardiovascular disease

Cardiovascular disease disproportionately affects people with diabetes and is a leading cause of death. Glycemic control has so far not been conclusively shown to decrease cardiovascular events. The therapeutic agents used in treating glycemia have different effects on cardiovascular risks and, therefore, may have different effects on outcome. Insulin sensitizers impact cardiovascular risk factors, including dyslipidemia and fibrinolysis. Metformin is the only oral antidiabetic medication shown to decrease cardiovascular events independent of glycemic control. Thiazolidinediones improve insulin resistance and lower insulin concentrations, which is beneficial because hyperinsulinemia is an independent predictor of cardiovascular disease. Insulin therapy acutely reduces cardiovascular mortality and morbidity in patients with diabetes and known coronary artery disease and also in patients with hyperglycemia when critically ill, but the long-term effects are unclear. In contrast, insulin secretagogues have very little effect on both cardiovascular risk factors and outcomes.

The stepwise approach to the management of type 2 diabetes

As the prevalence of type 2 diabetes continues to increase worldwide, there is an enhanced need for effective disease management. Type 2 diabetes is managed through a stepwise program of intensive therapy that consists of lifestyle modifications and sequential addition of oral antihyperglycemic agents and insulin as necessary. Successful implementation of this approach lessens the microvascular complications of the disease and promotes a lifestyle that may reduce macrovascular complications and comorbidities. Because of the progressive pancreatic beta-cell failure that causes hyperglycemia in type 2 diabetes, many people with type 2 diabetes will ultimately require insulin for disease management. Insulin may be used alone or in combination with oral agents to achieve glycemic control with a minimum of side effects. Although disease management regimens must be tailored to the needs of the individual with type 2 diabetes, the health care provider should always employ an aggressive, treat-to-target strategy to lower hyperglycemia and lessen diabetes-related risk factors.

Sulfonylurea treatment of type 2 diabetes mellitus: focus on glimepiride

Sulfonylureas, which have evolved through two generations since their introduction nearly 50 years ago, remain the most frequently prescribed oral agents for treatment of patients with type 2 diabetes mellitus. Glyburide, glipizide, and glimepiride, the newest sulfonylureas, are as effective at lowering plasma glucose concentrations as first-generation agents but are more potent, better tolerated, and associated with a lower risk of adverse effects. Differences in their binding affinity to the beta-cell sulfonylurea receptor have been described, with preservation of cardioprotective responses to ischemia with glimepiride. Clinical studies have shown glimepiride to be safe and effective in reducing fasting and postprandial glucose levels, as well as glycosylated hemoglobin concentrations, with dosages of 1-8 mg/day. In comparative trials, glimepiride was as effective in lowering glucose levels as glyburide and glipizide, but glimepiride was associated with a reduced likelihood of hypoglycemia and a smaller increase in fasting insulin and C-peptide levels than glyburide, and a more rapid lowering of fasting plasma glucose levels than glipizide. Glimepiride also improves first-phase insulin secretion, which plays an important role in reducing postprandial hyperglycemia. Insulin secretagogues, specifically glimepiride, merit consideration as first-line therapy for patients with type 2 diabetes.

Synergistic effect on insulin secretion from INS-1 cells of a sulfonylurea and a phosphodiesterase 3 inhibitor

The effects on insulin secretion from INS-1 cells of varying concentrations of the sulfonylurea glyburide and the PDE3 inhibitor milrinone, separately and in combination were measured. Over a range of concentrations the effects of the two drugs in combination were more than additive. A response surface model was fit to the data and was found to describe the data well. From this model, it was apparent that a significant synergistic effect upon insulin secretion existed over a wide range of combinations of the two drugs.

Type 2 diabetes mellitus: what is the optimal treatment regimen?

Treatment options for type 2 diabetes mellitus currently consist of insulin sensitizers, alpha-glucosidase inhibitors, secretagogues, and insulin. However, the emphasis on initial therapy has been shifting from secretagogues and alpha-glucosidase inhibitors to insulin sensitizers such as metformin and the thiazolidinediones (TZDs). This article outlines the benefits of treatment with sensitizers vis à vis alpha-glucosidase inhibitors and secretagogues as part of a comprehensive treatment algorithm for type 2 diabetes. Secretagogues and alpha-glucosidase inhibitors effectively lower plasma glucose levels only, whereas insulin sensitizers reduce several important cardiac risk factors in addition to reducing plasma glucose levels. TZDs, in particular, are also beneficial for their ability to preserve or even rejuvenate pancreatic beta-cell function. The treatment algorithm has a layered approach, beginning with a combination of insulin-sensitizer therapy and incrementally progressing to triple oral therapy with the addition of secretagogues and, if necessary, the addition of subcutaneous insulin to maintain glycemic control.

A Comparison of Agents Used to Manage Type 2 Diabetes Mellitus

In patients with type 2 diabetes mellitus, the traditional method of initiating therapy with a sulfonylurea and increasing the dosage until maximum levels are reached before adding an insulin-sensitizing agent has persisted and should be re-evaluated. Similarly, the current practice of starting therapy with one agent and increasing to maximum dosage before adding a second agent, rather than starting with combination therapy, also needs to be addressed. There is much evidence to suggest that initiating therapy with lower doses of two agents that have complementary effects can increase the overall efficacy and decrease the incidence of adverse effects. Clearly, there is a need for a paradigm shift away from the traditional approach of therapy using insulin secretagogues to a more pathophysiologic approach using an insulin-sensitizing agent, such as the thiazolidinediones. The thiazolidinediones have been shown to reduce insulin resistance, improve the ability of beta-cells to produce insulin, and decrease cardiac risk factors. By reducing insulin resistance, improving glycemic control, and preserving beta-cell function with a thiazolidinedione early in the course of therapy, it is likely that durable glycemic control will be achieved and both microvascular and macrovascular complications may be reduced. Furthermore, early use of an insulin-sensitizing agent either alone or incombination is expected to improve both acute and long-term outcomes in patients with type 2 diabetes.

Drug therapy of diabetes in the elderly

The prevalence of type 2 diabetes mellitus is increasing in the elderly. Although type 1 diabetic patients are living longer, over 95% of elderly people affected with diabetes have type 2 diabetes. This segment of the population, comprising men and women older than 65 years of age, is more likely to develop coexisting illnesses predisposing to the development of diabetes and complicating its management. In addition to changes in lifestyle, inherent age-related changes in carbohydrate metabolism contribute to the development of type 2 diabetes in old age. The long-term outcome of tight blood sugar control in the elderly is not known. Nevertheless the principles of management of type 2 diabetes in the elderly are essentially the same as in young- or middle-aged diabetic patients. Lifestyle modifications remain the cornerstone of medical therapy. When diet and exercise fail to achieve proper glycemic control, oral pharmacologic therapy and/or insulin therapy is indicated. The recently available oral glucose lowering agents in the market along with the newer types of insulin can be used in elderly diabetic patients. The effect of aging on metabolism and drug elimination kinetics must, however, be taken into consideration. In particular, it should be borne in mind that the risk of hypoglycemia is more deleterious in the elderly and should be avoided. In this review, the various pharmacologic agents available for the management of diabetes will be reviewed and some pertinent clinical guidelines will be suggested.

Current therapeutic algorithms for type 2 diabetes

Although type 2 diabetes is a heterogeneous disorder, there are certain management goals that are common to all patients. Tight metabolic control reduces the complication rates; therefore, for patients with type 2 diabetes, lowering the hemoglobin A1c toward normal is a major goal, as is the achievement of normal lipids and blood pressure. This article first discusses the standard regimens and agents available and then focuses on the newer approaches to reaching these goals.