The Role of Pramlintide for Weight Loss

Managing obesity in adults with type 1 diabetes

As the prevalence of obesity has reached epidemic proportions, its prevalence has also increased among adults living with type 1 diabetes mellitus. Unlike the pathophysiologic relationship between obesity and type 2 diabetes mellitus, the relationship between obesity and type 1 diabetes mellitus, and management of obesity in the setting of type 1 diabetes mellitus, have not been well reviewed. In this article, we discuss the comprehensive management of obesity in adults with type 1 diabetes mellitus, focusing on medical nutrition therapy and adjunct therapies such as weight loss-promoting medications and metabolic/bariatric surgery.

Pramlintide an Adjunct to Insulin Therapy: Challenges and Recent Progress in Delivery

Dysregulation of various glucoregulatory hormones lead to failure of insulin monotherapy in patients with diabetes mellitus due to various reasons, including severe hypoglycemia, glycemic hypervariability, and an increased risk of microvascular complications. However, pramlintide as an adjunct to insulin therapy enhances glucagon suppression and thereby offers improved glycemic control. Clinical studies have shown that pramlintide improves glycemic control, reduces postprandial glucose excursions, and promotes weight loss in patients with type 1 and type 2 diabetes. Although clinical benefits of pramlintide are well reported, there still exists a high patient resistance for the therapy, as separate injections for pramlintide and insulin must be administered. Although marketed insulin formulations generally demonstrate a peak action in 60-90 minutes, pramlintide elicits its peak concentration at around 20-30 minutes after administration. Thus, owing to the significant differences in pharmacokinetics of exogenously administered pramlintide and insulin, the therapy fails to elicit its action otherwise produced by the endogenous hormones. Hence, strategies such as delaying the release of pramlintide by using inorganic polymers like silica, synthetic polymers like polycaprolactone, and lipids have been employed. Also, approaches like noncovalent conjugation, polyelectrolyte complexation, and use of amphiphilic excipients for codelivery of insulin and pramlintide have been explored to address the issues with pramlintide delivery and improve patient adherence to the therapy. This approach may usher in a new era of diabetes management, offering patients multiple options to tailor their treatment and improve their quality of life. SIGNIFICANCE STATEMENT: To our knowledge, this is the first report that summarizes various challenges in insulin and pramlintide codelivery and strategies to overcome them. The paper also provides deeper insights into various novel formulation strategies for pramlintide that could further broaden the reader's understanding of peptide codelivery.

Obesity and Type 2 Diabetes: Adiposopathy as a Triggering Factor and Therapeutic Options

Obesity and type 2 diabetes (T2DM) are major public health concerns associated with serious morbidity and increased mortality. Both obesity and T2DM are strongly associated with adiposopathy, a term that describes the pathophysiological changes of the adipose tissue. In this review, we have highlighted adipose tissue dysfunction as a major factor in the etiology of these conditions since it promotes chronic inflammation, dysregulated glucose homeostasis, and impaired adipogenesis, leading to the accumulation of ectopic fat and insulin resistance. This dysfunctional state can be effectively ameliorated by the loss of at least 15% of body weight, that is correlated with better glycemic control, decreased likelihood of cardiometabolic disease, and an improvement in overall quality of life. Weight loss can be achieved through lifestyle modifications (healthy diet, regular physical activity) and pharmacotherapy. In this review, we summarized different effective management strategies to address weight loss, such as bariatric surgery and several classes of drugs, namely metformin, GLP-1 receptor agonists, amylin analogs, and SGLT2 inhibitors. These drugs act by targeting various mechanisms involved in the pathophysiology of obesity and T2DM, and they have been shown to induce significant weight loss and improve glycemic control in obese individuals with T2DM.

Pharmacological Support for the Treatment of Obesity-Present and Future

Obesity is a growing civilization problem, associated with a number of negative health consequences affecting almost all tissues and organs. Currently, obesity treatment includes lifestyle modifications (including diet and exercise), pharmacologic therapies, and in some clinical situations, bariatric surgery. These treatments seem to be the most effective method supporting the treatment of obesity. However, they are many limitations to the options, both for the practitioners and patients. Often the comorbidities, cost, age of the patient, and even geographic locations may influence the choices. The pharmacotherapy of obesity is a fast-growing market. Currently, we have at our disposal drugs with various mechanisms of action (directly reducing the absorption of calories-orlistat, acting centrally-bupropion with naltrexone, phentermine with topiramate, or multidirectional-liraglutide, dulaglutide, semaglutide). The drugs whose weight-reducing effect is used in the course of the pharmacotherapy of other diseases (e.g., glucose-sodium cotransporter inhibitors, exenatide) are also worth mentioning. The obesity pharmacotherapy is focusing on novel therapeutic agents with improved safety and efficacy profiles. These trends also include an assessment of the usefulness of the weight-reducing properties of the drugs previously used for other diseases. The presented paper is an overview of the studies related to both drugs currently used in the pharmacotherapy of obesity and those undergoing clinical trials, taking into account the individual approach to the patient.

Weight-centric treatment of type 2 diabetes mellitus

Background

Chronic non-communicable diseases (CNCD) represent a major cause of morbidity and mortality. Type 2 diabetes mellitus (T2DM) is one of the most prevalent CNCD that is associated with a significant medical and economic burden. One of the main modifiable risk factors of T2DM is obesity. Many medications used for T2DM can lead to weight gain, worsening one of the root causes of this disease.

Methods

In this clinical review, we study the effect of medications for T2DM on body weight. We used MEDLINE, Google scholar, PubMed, Scopus, and Embase databases to search for relevant studies between 1 January 1950 to 20 September 2022 in English language. Here, we review the most prescribed medications for T2DM and summarize their effect on patients' body weight. We will also present an expert opinion on a recommended weight-centric approach to treat T2DM.

Results

Multiple T2DM medications have been associated with weight gain. Insulin, sulfonylureas, thiazolidinediones and meglitinides may increase body weight. However, biguanides (e.g., metformin), glucagon-like peptide-1 agonists (e.g., semaglutide, liraglutide, tirzepatide), sodium-glucose cotransporter 2 inhibitors, and amylin analogs (e.g., pramlintide) are associated with significant weight loss. Dipeptidyl peptidase-4 inhibitors are considered weight neutral medications. Experts in the fields of endocrinology and obesity recommend utilizing a weight-centric approach when treating T2DM.

Conclusion

Considering the high prevalence and debilitating complication of T2DM, it is of utmost importance to shift from a weight gain approach (i.e., insulin, sulfonylureas) into a weight loss/neutral one (i.e., GLP-1 agonists, SGLT-2 inhibitors, metformin).

Managing weight and glycaemic targets in people with type 2 diabetes—How far have we come?

Introduction

As the vast majority of people with type 2 diabetes (T2D) are also overweight or obese, healthcare professionals (HCP) are faced with the task of addressing both weight management and glucose control. In this narrative review, we aim to identify the challenges of reaching and maintaining body weight targets in people with T2D and highlight current and future treatment interventions.

Methods

A search of the PubMed database was conducted using the search terms “diabetes” and “weight loss.”

Results

According to emerging evidence, treating obesity may be antecedent to the development and progression of T2D. While clinical benefits typically set in upon achieving a weight loss of 3–5%, these benefits are progressive leading to further health improvements, and weight loss of >15% can have a disease‐modifying effect in people with T2D, an outcome that up to recently could not be achieved with any blood glucose‐lowering pharmacotherapy. However, advanced treatment options with weight‐loss effects currently in development including the dual GIP/GLP‐1 receptor agonists may enable simultaneous achievement of individual glycemic and weight goals.

Conclusion

Despite considerable therapeutic progress, there is still a large unmet medical need in patients with T2D who miss their individualized glycemic and weight‐loss targets. Nonetheless, it is to be expected that development of future therapies and their use will favourably change the scenario of weight and glucose control in T2D.

Linking hIAPP misfolding and aggregation with type 2 diabetes mellitus: a structural perspective

There are over 40 identified human disorders that involve certain proteins folding incorrectly, accumulating in the body causing damage to cells and organs and causing disease. Type 2 Diabetes Mellitus (T2DM) is one of these protein misfolding disorders (PMDs) and involves human islet amyloid polypeptide (hIAPP) misfolding and accumulating in parts of the body, primarily in the pancreas, causing damage to islet cells and affecting glucose regulation. In this review, we have summarised our current understanding of what causes hIAPP to misfold, what conformations are found in different parts of the body with a particular focus on what is known about the structure of hIAPP and how this links to T2DM. Understanding the molecular basis behind these misfolding events is essential for understanding the role of hIAPP to develop better therapeutics since type 2 diabetes currently affects over 4.9 million people in the United Kingdom alone and is predicted to increase as our population ages.

Injectable Biodegradable Silica Depot: Two Months of Sustained Release of the Blood Glucose Lowering Peptide, Pramlintide

Diabetes mellitus is a major healthcare challenge. Pramlintide, a peptide analogue of the hormone amylin, is currently used as an adjunct with insulin for patients who fail to achieve glycemic control with only insulin therapy. However, hypoglycemia is the dominant risk factor associated with such approaches and careful dosing of both drugs is needed. To mitigate this risk factor and compliance issues related to multiple dosing of different drugs, sustained delivery of Pramlintide from silica depot administered subcutaneously (SC) was investigated in a rat model. The pramlintide-silica microparticle hydrogel depot was formulated by spray drying of silica sol-gels. In vitro dissolution tests revealed an initial burst of pramlintide followed by controlled release due to the dissolution of the silica matrix. At higher dosing, pramlintide released from subcutaneously administered silica depot in rats showed a steady concentration of 500 pM in serum for 60 days. Released pramlintide retained its pharmacological activity in vivo, as evidenced by loss of weight. The biodegradable silica matrix offers a sustained release of pramlintide for at least two months in the rat model and shows potential for clinical applications.

Hepatopathy Associated With Type 1 Diabetes: Distinguishing Non-alcoholic Fatty Liver Disease From Glycogenic Hepatopathy

Autoimmune destruction of pancreatic β-cells results in the permanent loss of insulin production in type 1 diabetes (T1D). The daily necessity to inject exogenous insulin to treat hyperglycemia leads to a relative portal vein insulin deficiency and potentiates hypoglycemia which can induce weight gain, while daily fluctuations of blood sugar levels affect the hepatic glycogen storage and overall metabolic control. These, among others, fundamental characteristics of T1D are associated with the development of two distinct, but in part clinically similar hepatopathies, namely non-alcoholic fatty liver disease (NAFLD) and glycogen hepatopathy (GlyH). Recent studies suggest that NAFLD may be increasingly common in T1D because more people with T1D present with overweight and/or obesity, linked to the metabolic syndrome. GlyH is a rare but underdiagnosed complication hallmarked by extremely brittle metabolic control in, often young, individuals with T1D. Both hepatopathies share clinical similarities, troubling both diagnosis and differentiation. Since NAFLD is increasingly associated with cardiovascular and chronic kidney disease, whereas GlyH is considered self-limiting, awareness and differentiation between both condition is important in clinical care. The exact pathogenesis of both hepatopathies remains obscure, hence licensed pharmaceutical therapy is lacking and general awareness amongst physicians is low. This article aims to review the factors potentially contributing to fatty liver disease or glycogen storage disruption in T1D. It ends with a proposal for clinicians to approach patients with T1D and potential hepatopathy.

Future directions in obesity pharmacotherapy

There is a growing unmet need for more effective treatment of obesity and its complications. While current anti-obesity medications are effective and offer real clinical benefits over diet and lifestyle interventions, they cannot meet the levels of efficacy and reduction of hard endpoint outcomes seen with bariatric surgery. As knowledge on the control of body weight unravels, the complexity of this physiology opens the opportunity to new druggable targets. Currently, gut peptide analogues such as semaglutide, a glucagon like peptide-1 (GLP-1) receptor agonist, and the dual agonist GLP-1 and gastric inhibitory polypeptide (GIP) tirzepatide are the furthest advanced in clinical development and seem likely to meet current regulatory requirements within the next year or so. However, current regulatory requirements are out of step with the efficacy of new compounds and concepts relating to obesity and its complications. Many other drugs in early development will target different pathways of energy balance, raising the possibility of drug combinations to maximise efficacy as for other chronic disease such as hypertension and diabetes. This will allow more complex and personalised guidelines to evolve.

The best drug supplement for obesity treatment: a systematic review and network meta-analysis

BACKGROUND

Obesity is a complex disease with an increasing prevalence worldwide. There are different weight-management options for obesity treatment, including dietary control, exercise, surgery, and medication. Medications are always associated with different responses from different people. More safety and efficacy of drugs with fewer side effects are valuable for any clinical condition. In this systematic review and network meta-analysis, different anti-obesity drugs are compared to identify the most effective drug.

METHODS

All relevant studies were extracted by searching national and international databases of SID, MagIran, ProQuest, PubMed, Science Direct, Scopus, Web of Science (WoS), and Google Scholar without time limit until October 2020. Finally, the meta-analysis was performed with the 11 remaining studies containing 14 different drug supplements. The standardized mean difference (SMD) was calculated at a 95% confidence interval (CI) to evaluate the effects of each treatment group compared with placebo. A random-effect model was used to evaluate the effect of individual studies on the final result. Heterogeneity and incompatibility of the network were assessed by Cochran's Q and Higgins I2, and the Net Heat chart, respectively. Data analysis was performed using R software.

RESULTS

Our results showed that there were significant mean effects in people intervened with Phentermine 15.0 mg + Topiramate 92.0 mg, Phentermine 7.5 mg + Topiramate 46.0 mg, Pramlintide, Naltrexone + Bupropion 32, and Liraglutide, with SMD effects size = - 9.1, - 7.4, - 6.5, - 5.9, - 5.35, respectively.

CONCLUSION

This study was performed to compare the effect of different drugs used for weight loss in obese patients. The most effective drugs for weight loss were phentermine and topiramate, pramlintide, naltrexone, bupropion, and liraglutide compared to placebo treatment, respectively. This study provides new insights into anti-obesity drugs and hopes to shed new light on future research to manage and treat obesity.

The Calcitonin Receptor Plays a Major Role in Glucose Regulation as a Function of Dual Amylin and Calcitonin Receptor Agonist Therapy

Amylin treatment improves body weight and glucose control, although it is limited by a short action and need for high doses. Dual amylin and calcitonin receptor agonists (DACRAs) are dual amylin and calcitonin receptor agonists with beneficial effects beyond those of amylin. However, to what extent the additional benefits reside in their higher potency or their targeting of the calcitonin receptor remains unclear. Here we deconstruct the receptors involved in the effects of a DACRA, KBP-088, by comparing it to rat amylin (rAMY), rat calcitonin (rCT), and their combination in obese high-fat diet (HFD) and diabetic Zucker diabetic fatty (ZDF) rats. HFD-fed Sprague-Dawley rats and ZDF rats were treated for 4 weeks with KBP-088 (5 µg/kg per day), rAMY (300 µg/kg per day), rCT (300 µg/kg per day), and the combination of rAMY and rCT (300+300 µg/kg per day) using infusion pumps. Body weight, food intake, fasting glycemia, glycated hemoglobin type A1c levels, and glucose tolerance were assessed. In obese HFD-fed rats, KBP-088, rAMY, and the combination of rAMY and rCT significantly reduced body weight and improved glucose tolerance, whereas rCT alone had no effect. In diabetic ZDF rats, rCT was efficient in lowering fasting glycemia similar to rAMY, whereas dual activation by KBP-088 and the combination of rAMY and rCT were superior to activating either receptor alone. In conclusion, calcitonin therapy regulates fasting blood glucose in a diabetic rat model, thereby underscoring the importance of calcitonin receptor activation as well as the known role of amylin receptor agonism in the potent metabolic benefits of this group of peptides. SIGNIFICANCE STATEMENT: We deconstruct the receptors activated by dual amylin and calcitonin receptor agonist (DACRA) therapy to elucidate through which receptor the beneficial metabolic effects of the DACRAs are mediated. We show that calcitonin receptor activation is important for blood glucose regulation in diabetes. This is in addition to the known metabolic beneficial role of amylin receptor activation. These data help in understanding the potent metabolic benefits of the DACRAs and underline the potential of DACRAs as treatment for diabetes and obesity.

The Dual Amylin- and Calcitonin-Receptor Agonist KBP-042 Works as Adjunct to Metformin on Fasting Hyperglycemia and HbA1c in a Rat Model of Type 2 Diabetes

KBP-042 is a dual amylin and calcitonin receptor agonist that increases glucose tolerance and insulin action and reduces body weight in rat models of obesity and prediabetes. The objective of the present study was to 1) evaluate KBP-042 as a treatment of late-stage type 2 diabetes in a rat model and 2) assess the value of adding KBP-042 to the standard of care, metformin, to consider KBP-042 as a relevant drug for treating patients with type 2 diabetes. Two studies were included: an intervention study and a prevention study. In the intervention study, treatment with 5 µg/kg KBP-042 was initiated in 11-week-old Zucker diabetic fatty (ZDF) rats, in which glucose tolerance, fasting glycemia, and glycated hemoglobin were assessed after 4 weeks. In the prevention study, either metformin (400 mg/kg), KBP-042 (5 µg/kg), or a combination of both were administered to ZDF rats for a total of 9 weeks. Glycemia, glucose tolerance, and insulin tolerance were tested. Furthermore, fasting plasma insulin and glucagon levels were evaluated. Finally, pancreatic content of insulin was assessed as a surrogate marker of beta-cell mass. It was found that KBP-042 was efficient in lowering fasting plasma glucose as well as improving glucose tolerance, both as prevention and intervention of disease progression. Furthermore, KBP-042 was efficient in combination with metformin and had additional effects compared with either therapy alone. In conclusion, KBP-042 is a highly relevant therapeutic candidate against type 2 diabetes, effective both as an add-on therapy to metformin and as a stand-alone therapy.

Synthesis and amylin receptor activity of glycomimetics of pramlintide using click chemistry

Pramlintide (Symlin®), a synthetic analogue of the neuroendocrine hormone amylin, is devoid of the tendency to form cytotoxic amyloid fibrils and is currently used in patients with type I and type II diabetes mellitus as an adjunctive therapy with insulin or insulin analogues. As part of an on-going search for a pramlintide analogue with improved pharmacokinetic properties, we herein report the synthesis of mono- and di-glycosylated analogues of pramlintide and their activity at the AMY1(a) receptor. Introduction of N-glycosylated amino acids into the pramlintide sequence afforded the native N-linked glycomimetics whilst use of Cu(i)-catalysed azide-alkyne 1,3-dipolar cycloaddition (click) chemistry delivered 1,2,3-triazole linked glycomimetics. AMY1(a) receptor activity was retained by incorporation of single or multiple GlcNAc moieties at positions 21 and 35 of native pramlintide. Importantly, no difference in AMY1(a) activity was observed between native N-linked glycomimetics and 1,2,3-triazole linked glycomimetics demonstrating that the click variants can act as surrogates for the native N-glycosides in a biological setting.

Altered gut and adipose tissue hormones in overweight and obese individuals: cause or consequence?

The aim of this article is to review the research into the main peripheral appetite signals altered in human obesity, together with their modifications after body weight loss with diet and exercise and after bariatric surgery, which may be relevant to strategies for obesity treatment. Body weight homeostasis involves the gut–brain axis, a complex and highly coordinated system of peripheral appetite hormones and centrally mediated neuronal regulation. The list of peripheral anorexigenic and orexigenic physiological factors in both animals and humans is intimidating and expanding, but anorexigenic glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY (PYY) and orexigenic ghrelin from the gastrointestinal tract, pancreatic polypeptide (PP) from the pancreas and anorexigenic leptin from adiposites remain the most widely studied hormones. Homeostatic control of food intake occurs in humans, although its relative importance for eating behaviour is uncertain, compared with social and environmental influences. There are perturbations in the gut–brain axis in obese compared with lean individuals, as well as in weight-reduced obese individuals. Fasting and postprandial levels of gut hormones change when obese individuals lose weight, either with surgical or with dietary and/or exercise interventions. Diet-induced weight loss results in long-term changes in appetite gut hormones, postulated to favour increased appetite and weight regain while exercise programmes modify responses in a direction expected to enhance satiety and permit weight loss and/or maintenance. Sustained weight loss achieved by bariatric surgery may in part be mediated via favourable changes to gut hormones. Future work will be necessary to fully elucidate the role of each element of the axis, and whether modifying these signals can reduce the risk of obesity.

Cooperative interaction between leptin and amylin signaling in the ventral tegmental area for the control of food intake

Peripheral coadministration of amylin and leptin produces enhanced suppression of food intake and body weight, but the central nuclei mediating these effects remain unclear. Because each of these peptides controls feeding via actions at the ventral tegmental area (VTA), we tested the hypothesis that the VTA is a site of action for the cooperative effects of leptin and amylin on energy balance control. First, we show that intra-VTA injection of amylin and leptin at doses of each peptide that are effective in reducing food intake and body weight when administered separately produces an enhanced suppression of feeding when administered in combination. We also demonstrate that subthreshold doses of both amylin and leptin cause significant hypophagia and body weight loss when coadministered into the VTA. Additionally, we provide evidence that VTA amylin receptor blockade significantly attenuates the ability of intra-VTA leptin to reduce feeding and body weight gain. Together, these data provide the first evidence that the VTA mediates the interaction of amylin and leptin to cooperatively promote negative energy balance.

Combating the dual burden: therapeutic targeting of common pathways in obesity and type 2 diabetes

The increasing prevalence of obesity is contributing substantially to the ongoing epidemic of type 2 diabetes. Abdominal adiposity, a feature of ectopic fat syndrome, is associated with silent inflammation, abnormal hormone secretion, and various metabolic disturbances that contribute to insulin resistance and insulin secretory defects, resulting in type 2 diabetes, and induce a toxic pattern that leads to cardiovascular disease, liver pathologies, and cancer. Despite the importance of weight control strategies in the prevention and management of type 2 diabetes, long-term results from lifestyle or drug interventions are generally disappointing. Furthermore, most of the classic glucose-lowering drugs have a side-effect of weight gain, which renders the management of most overweight or obese people with type 2 diabetes even more challenging. Many anti-obesity pharmacological drugs targeting central control of appetite were withdrawn from the market because of safety concerns. The gastrointestinal lipase inhibitor orlistat was the only anti-obesity drug available until the recent US, but not European, launch of phentermine-controlled-release topiramate and lorcaserin. Improved knowledge about bodyweight regulation opens new prospects for the potential use of peptides derived from the gut or the adipose tissue. Combination therapy will probably be necessary to avoid compensatory mechanisms and potentiate initial weight loss while avoiding weight regain. New glucose-lowering treatments, especially glucagon-like peptide-1 receptor agonists and sodium glucose cotransporter-2 inhibitors, offer advantages over traditional antidiabetic drugs by promoting weight loss while improving glucose control. In this Review, we explore the overlapping pathophysiology and also how various treatments can, alone or in combination, combat the dual burden of obesity and type 2 diabetes.

Liraglutide as additional treatment to insulin in obese patients with type 1 diabetes mellitus

OBJECTIVE

Because approximately 40% of patients with type 1 diabetes have the metabolic syndrome, we tested the hypothesis that addition of liraglutide to insulin in obese patients with type 1 diabetes will result in an improvement in plasma glucose concentrations, a reduction in hemoglobin A1c (HbA1c), a fall in systolic blood pressure, and weight loss.

METHODS

This is a retrospective analysis of data obtained from 27 obese patients with type 1 diabetes treated with liraglutide in addition to insulin. Patients were also treated for hypertension. Paired t tests were used to compare the changes in HbA1c, insulin doses, body weight, body mass index, 4-week mean blood glucose concentrations (28-day insulin pump mean blood glucose), blood pressure, and lipid parameters prior to and 180 ± 14 days after liraglutide therapy.

RESULTS

Mean glucose concentrations fell from 191 ± 6 to 170 ± 6 mg/dL (P = .002). HbA1c fell from 7.89 ± 0.13% to 7.46 ± 0.13% (P = .001), without an increase in frequency of hypoglycemia. Mean body weight fell from 96.20 ± 3.68 kg to 91.56 ± 3.78 kg (P<.0001). Daily total and bolus doses of insulin fell from 73 ± 6 to 60 ± 4 (P = .008) units and from 40 ± 5 to 29 ± 3 units (P = .011), respectively. Mean systolic blood pressure fell from 130 ± 3 to 120 ± 4 mm Hg (P = .020).

CONCLUSION

Addition of liraglutide to insulin in obese patients with type 1 diabetes mellitus leads to improvements in glycemic control and HbA1c and to reductions in insulin dose, systolic blood pressure, and body weight.

A novel oral dual amylin and calcitonin receptor agonist (KBP-042) exerts antiobesity and antidiabetic effects in rats

The present study investigated a novel oral dual amylin and calcitonin receptor agonist (DACRA), KBP-042, in head-to-head comparison with salmon calcitonin (sCT) with regard to in vitro receptor pharmacology, ex vivo pancreatic islet studies, and in vivo proof of concept studies in diet-induced obese (DIO) and Zucker diabetic fatty (ZDF) rats. In vitro, KBP-042 demonstrated superior binding affinity and activation of amylin and calcitonin receptors, and ex vivo, KBP-042 exerted inhibitory action on stimulated insulin and glucagon release from isolated islets. In vivo, KBP-042 induced a superior and pronounced reduction in food intake in conjunction with a sustained pair-fed corrected weight loss in DIO rats. Concomitantly, KBP-042 improved glucose homeostasis and reduced hyperinsulinemia and hyperleptinemia in conjunction with enhanced insulin sensitivity. In ZDF rats, KBP-042 induced a superior attenuation of diabetic hyperglycemia and alleviated impaired glucose and insulin tolerance. Concomitantly, KBP-042 preserved insulinotropic and induced glucagonostatic action, ultimately preserving pancreatic insulin and glucagon content. In conclusion, oral KBP-042 is a novel DACRA, which exerts antiobesity and antidiabetic efficacy by dual modulation of insulin sensitivity and directly decelerating stress on the pancreatic α- and β-cells. These results could provide the basis for oral KBP-042 as a novel therapeutic agent in type 2 diabetes.

Activity of pramlintide, rat and human amylin but not Aβ1-42 at human amylin receptors

Amylin is a neuroendocrine hormone involved in glucose regulation. An amylin analog, pramlintide, is used to treat insulin-requiring diabetes. Its anorexigenic actions give it potential as an obesity treatment. There are 3 amylin receptors (AMY1, AMY2, AMY3), comprising the calcitonin receptor and receptor activity-modifying proteins 1, 2, and 3, respectively. The pharmacology of pramlintide at each subtype has not been determined whereas the unrelated peptide β-amyloid 1-42 (Aβ1-42) has recently been proposed to be a specific agonist of the AMY3 receptor. We investigated the actions of Aβ1-42 and pramlintide, compared with human and rat amylin at the calcitonin receptor, AMY1, AMY2, and AMY3 receptors, measuring the cAMP response in human embryonic kidney 293S and Cos 7 cells. Pramlintide activated all receptors with a slight preference for AMY1. No cAMP response was detected with Aβ1-42 at any receptor, suggesting that it may not be a genuine agonist of AMY receptors.

Amylin exerts osteogenic actions with different efficacy depending on the diabetic status

Amylin displays osteogenic features, but its role in diabetic osteopenia is unclear. We examined the possible osteogenic action of amylin infusion for 3days into fructose-induced insulin-resistant (IR) and streptozotocin-induced type 2 diabetic (T2D) and normal (N) rats. Amylin failed to affect glycaemia or parathyroid hormone levels in any group, but reduced hyperinsulinemia in IR rats. In N rats, amylin increased bone formation rate and reduced osteoclast surface and erosive surface in the femoral metaphysis, and increased osteoprotegerin (OPG)/receptor activator of NFκB ligand (RANKL) mRNA ratio in the tibia. In T2D rats, amylin normalized trabecular structure parameters and increased osteoblast number and osteocalcin (OC) expression in long bones. In contrast, in IR rats, no apparent osteogenic effect of amylin in the femur was observed, although both OC and OPG/RANKL ratio were increased in the tibia. Our findings demonstrate a different osteogenic efficacy of amylin in two diabetic settings.

Do we need anti-obesity drugs?

The increasing global prevalence of obesity urgently requires an implementation of efficient preventive and therapeutic measures. Weight loss and its maintenance should be considered one of the most important strategies to reduce the incidence of obesity-related co-morbidities such as diabetes and cardiovascular diseases. Lifestyle modification focused on diet and physical activity represents the essential component of any kind of weight management. However, only an intensive lifestyle intervention can be efficient in terms of long-term weight loss. Anti-obesity drugs affect different targets in the central nervous system or peripheral tissues and improve regulatory and metabolic disturbances that contribute to the development of obesity. Anti-obesity medications provide modest additional fat loss to that achieved by lifestyle modification alone, reduce visceral fat stores, improve programme adherence, weight loss maintenance, diminish obesity-related health risks and improve a quality of life. Anti-obesity drugs do play a role in weight management. Their replacement with placebo is followed by weight regain. Due to adverse events, several anti-obesity drugs were withdrawn from the market over the past few years and currently only orlistat remains available for long-term obesity management. Drug withdrawals, failure of clinical trials with several new anti-obesity compounds as well as inappropriate demands of drug regulating agencies concerning the study protocol led to scepticism about the perspectives in the pharmacotherapy of obesity. However, recently developed anti-obesity medications such as gut hormone analogues and drug combinations provided encouraging results in terms of weight loss, safety and improvement of cardio-metabolic health risks.

Pramlintide: profile of an amylin analog

Amylin is a naturally occurring hormone that regulates food intake and postprandial glucose excursions. Amylin is synthesized in the β cell and cosecreted with insulin. Type 1 diabetes and insulin-requiring Type 2 diabetes are amylin-deficient as well as insulin-deficient states. Pramlintide is a synthetic amylin analog that is used for replacement therapy. Pramlintide therapy slows diabetes-mediated accelerated gastric emptying and restores meal-mediated suppression of glucagon secretion in patients with diabetes. Amylin receptors are primarily located in the CNS, which mediates all of its effects including decreases in food intake. In patients with diabetes, pramlintide treatment reduces hemoglobin A1C (HbA1c) 0.3-0.7% and decreases bodyweight. Side effects include nausea and hypoglycemia. Both can be minimized by an appropriate titration program. Recent pramlintide studies address improvements in delivery systems, use in pediatric and Type 2 diabetic populations, patient treatment satisfaction and new insights into its mechanisms of action.

The pharmacological treatment of obesity: Past, present and future

Currently, obesity presents one of the biggest health problems. Management strategies for weight reduction in obese individuals include changes in life style such as exercise and diet, behavioral therapy, and pharmacological treatment, and in certain cases surgical intervention. Diet and exercise are best for both prevention and treatment, but both require much discipline and are difficult to maintain. Drug treatment of obesity offer a possible adjunct, but it may only have modest results, limited by side effects; furthermore, the weight lowering effects last only as long as the drug is being taken and, unfortunately, as soon as the administration is stopped, the weight is regained. These strategies should be used in a combination for higher efficacy. Drugs used to induce weight loss have various effects: they increase satiety, reduce the absorption of nutrients or make metabolism faster; but their effect is usually moderate. In the past, several drugs were used in the pharmacological therapy of weight reduction including thyroid hormone, dinitrophenol, amphetamines and their analogues, e.g. fenfluramine, At present, only orlistat is available in the long term treatment (≥24 weeks) of obesity as sibutramine and rimonabant were withdrawn form the market. Several new anti-obesity drugs are being tested at present, and liraglutide, a GLP-1 analogue (incretin mimetic), is the most promising one. Orv. Hetil., 2012, 153, 363–373.

Polymeric particles for the controlled release of human amylin

Since its discovery the therapeutic use of the pancreatic hormone amylin has been limited due to its poor water solubility and propensity for amyloid aggregation. We have entrapped the human amylin protein in polymeric nanoparticles, using a single emulsion-solvent evaporation method and investigated its effectiveness in the controlled release of the peptide. Typical preparations composed of poly-ε-caprolactone had a mean particle size of approximately 200 nm, low polydispersity index, high protein entrapment efficiency (80%) and process yield (90%), and spherical and smooth surfaces. These nanoparticles presented a controlled release in vitro for approximately 240 h. Pharmacological evaluation in vivo by subcutaneous administration in fasting mice demonstrated the bioactivity and effectiveness of the released human amylin, resulting in reduced glycemia lasting for at least 36 h. These features indicate the potential for the use of a confined particulate system in the therapeutic controlled and sustained release of human amylin.

Amylin effect in extrapancreatic tissues participating in glucose homeostasis, in normal, insulin-resistant and type 2 diabetic state

Amylin is co-secreted with insulin, responds to the same stimuli, is anorectic, lowers body weight by reducing fat mass, and is proposed for diabetes treatment. We examined the effect of a 3-day constant infusion of close to physiological doses of amylin in Wistar rats, on glucotransporter expression, glycogen content (G), glycogen synthase a activity (GSa) and glucose transport (GT), in liver, muscle and fat from insulin resistant (IR) and type 2 diabetic (T2D) models, compared to normal (N) animals; plasma glucose and insulin were measured. Plasma insulin in IR was higher than in N or T2D, and amylin normalized the value. In both, IR and T2D, liver G was lower than normal, accompanied by GLUT-2, mRNA and protein, higher and lower, respectively, than in N; amylin normalized G in both groups, without changes in GLUT-2, except for an mRNA increase in T2D. In IR and T2D, muscle GSa was reduced, together with respective over- and under-GLUT-4 expression; amylin induced only a trend toward GSa normalization in both groups. In isolated adipocytes, GT and GLUT-4 in IR and T2D were lower and higher, respectively, than in N; after amylin, not only GT was normalized in both groups but also the response to insulin was much more pronounced, including that in N, without major changes in GLUT-4. This suggests that the beneficial effect of amylin in states running with altered glucose homeostasis could occur by partially acting on the hexose metabolism of the liver and mainly on that of the adipose tissue.

Amylin analogues in the treatment of diabetes mellitus: medicinal chemistry and structural basis of its function

Amylin, (islet amyloid polypeptide) or diabetes-associated peptide is co-secreted with insulin in the islet of Langerhans of diabetic patients in approximately 1:100, amylin-insulin ratio. The soluble form of amylin, an analogue of amylin, is used as a supplement to insulin in the treatment of type 1 diabetes. Co-administration of amylin analogue with insulin to patients with type 1 diabetes induced a larger reduction in proprandial hyperglycemia, with a concomitant reduction in the level of glucagon when compared to insulin monotherapy. The actions of amylin analogues appear to be synergistic to insulin, with which it is co-released from insulin-producing beta cells after a meal. Amylin analogues such as pramlintide has been shown to significantly reduce body weight, HbA1c values and even the dosage of insulin. A moderate weight loss can also be achieved in obese patients with or without diabetes. A major side effect of some amylin analogues includes nausea and excitation of the area postrema. This review examines the medicinal chemistry of amylin and its analogues and their effects.

Pharmacotherapy for obese adolescents

The pharmaceutical search to induce weight loss was precipitated by the United States Food and Drug Administration's (FDA) 1959 formal approval of phentermine for short-term weight loss despite limited research supporting its assertions of weight loss. In addition to sympathomimetic amine products like phentermine, other medications considered in this article include herbal products, sibutramine, orlistat, metformin, and rimonabant. The use of pharmacotherapy for morbidly obese adolescents should be part of a comprehensive weight-loss program that recommends diet, exercise, and behavioral modification. Side effects and the possibility of major adverse effects should be remembered when considering use of these products.

Molecular neuroendocrine targets for obesity therapy

PURPOSE OF REVIEW

Although energy balance is tightly regulated in order to maintain a specific level of adiposity, the incidence of obesity continues to increase. Consequently, it is essential that effective therapeutics for the treatment and prevention of obesity be developed. This review provides a brief update on some recent advances in the characterization of neuroendocrine targets for obesity therapy.

RECENT FINDINGS

During the review period, considerable progress occurred in the understanding of previously described neuroendocrine regulators of energy balance, and several novel targets have been identified. Moreover, the understanding of the neural circuitry and molecular mechanisms of the neuroendocrine regulation of energy homeostasis has been expanded.

SUMMARY

Energy balance is maintained by neuroendocrine signals arising from many tissues including the gastrointestinal tract and adipose tissue. These signals are integral to the cessation of meals and to the ability of the brain to monitor energy status and respond accordingly. Many current targets for obesity therapy are based on manipulating the activity of these signals and their receptors; however, to date, clinical-weight loss based on this strategy has been minimal and alternative approaches such as combinatorial therapies are emerging.