Lorcaserin, a 5-HT(2C) receptor agonist, reduces body weight by decreasing energy intake without influencing energy expenditure

Activation of Ventral Tegmental Area 5-HT2C Receptors Reduces Incentive Motivation

Obesity is primarily due to food intake in excess of the body's energetic requirements, intake that is not only associated with hunger but also the incentive value of food. The 5-hydroxytryptamine 2C receptor (5-HT_2CR) is a target for the treatment of human obesity. Mechanistically, 5-HT_2CRs are positioned to influence both homeostatic feeding circuits within the hypothalamus and reward circuits within the ventral tegmental area (VTA). Here we investigated the role of 5-HT_2CRs in incentive motivation using a mathematical model of progressive ratio (PR) responding in mice. We found that the 5-HT_2CR agonist lorcaserin significantly reduced both ad libitum chow intake and PR responding for chocolate pellets and increased c-fos expression in VTA 5-HT_2CR expressing γ-aminobutyric acid (GABA) neurons, but not 5-HT_2CR expressing dopamine (DA) neurons. We next adopted a chemogenetic approach using a 5-HT_2CR^CRE line to clarify the function of subset of 5-HT_2C receptor expressing VTA neurons in the modulation of appetite and food-motivated behavior. Activation of VTA 5-HT_2C receptor expressing neurons significantly reduced ad libitum chow intake, operant responding for chocolate pellets, and the incentive value of food. In contrast, chemogenetic inhibition of VTA 5-HT_2C receptor expressing neurons had no effect on the feeding behavior. These results indicate that activation of the subpopulation of 5-HT_2CR neurons within the VTA is sufficient to significantly reduce homeostatic feeding and effort-based intake of palatable food, and that this subset has an inhibitory role in motivational processes. These findings are relevant to the treatment of obesity.

Translational Modeling to Guide Study Design and Dose Choice in Obesity Exemplified by AZD1979, a Melanin-concentrating Hormone Receptor 1 Antagonist

In this study, we present the translational modeling used in the discovery of AZD1979, a melanin‐concentrating hormone receptor 1 (MCHr1) antagonist aimed for treatment of obesity. The model quantitatively connects the relevant biomarkers and thereby closes the scaling path from rodent to man, as well as from dose to effect level. The complexity of individual modeling steps depends on the quality and quantity of data as well as the prior information; from semimechanistic body‐composition models to standard linear regression. Key predictions are obtained by standard forward simulation (e.g., predicting effect from exposure), as well as non‐parametric input estimation (e.g., predicting energy intake from longitudinal body‐weight data), across species. The work illustrates how modeling integrates data from several species, fills critical gaps between biomarkers, and supports experimental design and human dose‐prediction. We believe this approach can be of general interest for translation in the obesity field, and might inspire translational reasoning more broadly.

Obesity: Current and potential pharmacotherapeutics and targets

Obesity is a global epidemic that contributes to a number of health complications including cardiovascular disease, type 2 diabetes, cancer and neuropsychiatric disorders. Pharmacotherapeutic strategies to treat obesity are urgently needed. Research over the past two decades has increased substantially our knowledge of central and peripheral mechanisms underlying homeostatic energy balance. Homeostatic mechanisms involve multiple components including neuronal circuits, some originating in hypothalamus and brain stem, as well as peripherally-derived satiety, hunger and adiposity signals that modulate neural activity and regulate eating behavior. Dysregulation of one or more of these homeostatic components results in obesity. Coincident with obesity, reward mechanisms that regulate hedonic aspects of food intake override the homeostatic regulation of eating. In addition to functional interactions between homeostatic and reward systems in the regulation of food intake, homeostatic signals have the ability to alter vulnerability to drug abuse. Regarding the treatment of obesity, pharmacological monotherapies primarily focus on a single protein target. FDA-approved monotherapy options include phentermine (Adipex-P®), orlistat (Xenical®), lorcaserin (Belviq®) and liraglutide (Saxenda®). However, monotherapies have limited efficacy, in part due to the recruitment of alternate and counter-regulatory pathways. Consequently, a multi-target approach may provide greater benefit. Recently, two combination products have been approved by the FDA to treat obesity, including phentermine/topiramate (Qsymia®) and naltrexone/bupropion (Contrave®). The current review provides an overview of homeostatic and reward mechanisms that regulate energy balance, potential therapeutic targets for obesity and current treatment options, including some candidate therapeutics in clinical development. Finally, challenges in anti-obesity drug development are discussed.

Type 2 Diabetes Treatment in the Patient with Obesity

Lifestyle modification is the cornerstone treatment of type 2 diabetes in the obese patient, and is highly effective at promoting glucose regulation. However, many individuals struggle over time to maintain optimal glycemic control and/or body weight with lifestyle modification. Therefore, additional therapeutic approaches are needed. Pharmacologic interventions have shown promising results for obesity-related diabetes complications. Not surprisingly though lifestyle modification and pharmacology may become ineffective for treating diabetes over time. Bariatric surgery is considered by some, but not all, to be the most effective and durable treatment for combating obesity. In fact many patients with type 2 diabetes have normalized glucose concentrations within days postoperation. Taken together, treatment of obesity in the patient with type 2 diabetes requires a multi-faceted approach.

FDA-Approved Anti-Obesity Drugs in the United States

Obesity is a growing health problem in our society and its treatment has been challenging. In recent decades, several anti-obesity drugs have been withdrawn from the market because of reported and documented adverse effects. After years of interruption, the US Food and Drug Administration (FDA) has recently approved multiple new anti-obesity drugs. The majority of these medications are taken orally, and only one is administered subcutaneously. In this article, we review the efficacy, adverse effects, and mechanism of action of all 5 FDA-approved drugs.

Exploratory Literature Meta-Analysis to Characterize the Relationship Between Early and Longer Term Body Weight Loss for Antiobesity Compounds

The presented analysis was performed to characterize the relationship between treatment-related early (week 4) and longer term (3-6 months) weight loss to understand the potential utility of 4-week proof-of-mechanism studies in the early decision-making process during clinical development of new antiobesity compounds. A regression-based meta-analysis was performed leveraging publically available clinical outcomes data to (1) characterize the within-trial relationship between treatment-related early and longer term body weight loss and (2) identify and quantify key covariate effects on this relationship. Data from 89 randomized clinical trials with 209 treatment arms, representing observations from 54 461 patients and 9 treatments, were available for the meta-analysis. Results indicated that (1) there is a correlation between treatment-related early and longer term body weight loss (r > 0.9), (2) baseline body weight influences the relationship between early and longer term weight loss, whereas comorbidity such as type 2 diabetes mellitus, class of drugs including GLP-1 analogues and the antiobesity compounds lorcaserin or phentermine/topiramate showed no significant effects on this relationship. The model was externally evaluated with data from the investigational compound beloranib, for which longer term weight loss could be successfully predicted based on early response data. Based on these results, the identified strong relationship between treatment-related early and longer term weight loss appears to be independent of mechanism of action. Thus, findings from this analysis can optimize design of clinical studies and facilitate development of new anti-obesity compounds.

Lorcaserin and CP-809101 reduce motor impulsivity and reinstatement of food seeking behavior in male rats: Implications for understanding the anti-obesity property of 5-HT2C receptor agonists

RATIONALE

The 5-HT2C receptor agonist lorcaserin (Belviq®) has been approved by the FDA for the treatment of obesity. Impulsivity is a contributory feature of some eating disorders.

OBJECTIVE

Experiments investigated the effect of lorcaserin and the highly selective 5-HT2C agonist CP-809101 on measures of impulsivity and on reinstatement of food-seeking behaviour, a model of dietary relapse. The effect of both drugs on 22-h deprivation-induced feeding was also examined, as was the effect of prefeeding in each impulsivity test.

RESULTS

Lorcaserin (0.3-0.6 mg/kg SC) and CP-809101 (0.6-1 mg/kg SC) reduced premature responding in rats trained on the 5-CSRTT and improved accuracy in a Go-NoGo task by reducing false alarms. At equivalent doses, both drugs also reduced reinstatement for food-seeking behaviour. Neither drug altered impulsive choice measured in a delay-discounting task. Lorcaserin (1-3 mg/kg SC) and CP-809101 (3-6 mg/kg SC) reduced deprivation-induced feeding but only at higher doses.

CONCLUSIONS

These results suggest that in addition to previously reported effects on satiety and reward, altered impulse control may represent a contributory factor to the anti-obesity property of 5-HT2C receptor agonists. Lorcaserin may promote weight loss by improving adherence to dietary regimens in individuals otherwise prone to relapse and may be beneficial in cases where obesity is associated with eating disorders tied to impulsive traits, such as binge eating disorder.

Mechanistic relationship between the vagal afferent pathway, central nervous system and peripheral organs in appetite regulation

The hypothalamus is a center of food intake and energy metabolism regulation. Information signals from peripheral organs are mediated through the circulation or the vagal afferent pathway and input into the hypothalamus, where signals are integrated to determine various behaviors, such as eating. Numerous appetite-regulating peptides are expressed in the central nervous system and the peripheral organs, and interact in a complex manner. Of such peptides, gut peptides are known to bind to receptors at the vagal afferent pathway terminal that extend into the mucosal layer of the digestive tract, modulate the electrical activity of the vagus nerve, and subsequently send signals to the solitary nucleus and furthermore to the hypothalamus. All peripheral peptides other than ghrelin suppress appetite, and they synergistically suppress appetite through the vagus nerve. In contrast, the appetite-enhancing peptide, ghrelin, antagonizes the actions of appetite-suppressing peptides through the vagus nerve, and appetite-suppressing peptides have attenuated effects in obesity as a result of inflammation in the vagus nerve. With greater understanding of the mechanism for food intake and energy metabolism regulation, medications that apply the effects of appetite-regulating peptides or implantable devices that electrically stimulate the vagus nerve are being investigated as novel treatments for obesity in basic and clinical studies.

Sex difference in physical activity, energy expenditure and obesity driven by a subpopulation of hypothalamic POMC neurons

OBJECTIVE

Obesity is one of the primary healthcare challenges of the 21st century. Signals relaying information regarding energy needs are integrated within the brain to influence body weight. Central among these integration nodes are the brain pro-opiomelanocortin (POMC) peptides, perturbations of which disrupt energy balance and promote severe obesity. However, POMC neurons are neurochemically diverse and the crucial source of POMC peptides that regulate energy homeostasis and body weight remains to be fully clarified.

METHODS

Given that a 5-hydroxytryptamine 2c receptor (5-HT2CR) agonist is a current obesity medication and 5-HT2CR agonist's effects on appetite are primarily mediated via POMC neurons, we hypothesized that a critical source of POMC regulating food intake and body weight is specifically synthesized in cells containing 5-HT2CRs. To exclusively manipulate Pomc synthesis only within 5-HT2CR containing cells, we generated a novel 5-HT 2C R (CRE) mouse line and intercrossed it with Cre recombinase-dependent and hypothalamic specific reactivatable Pomc (NEO) mice to restrict Pomc synthesis to the subset of hypothalamic cells containing 5-HT2CRs. This provided a means to clarify the specific contribution of a defined subgroup of POMC peptides in energy balance and body weight.

RESULTS

Here we transform genetically programed obese and hyperinsulinemic male mice lacking hypothalamic Pomc with increased appetite, reduced physical activity and compromised brown adipose tissue (BAT) into lean, healthy mice via targeted restoration of Pomc function only within 5-HT2CR expressing cells. Remarkably, the same metabolic transformation does not occur in females, who despite corrected feeding behavior and normalized insulin levels remain physically inactive, have lower energy expenditure, compromised BAT and develop obesity.

CONCLUSIONS

These data provide support for the functional heterogeneity of hypothalamic POMC neurons, revealing that Pomc expression within 5-HT2CR expressing neurons is sufficient to regulate energy intake and insulin sensitivity in male and female mice. However, an unexpected sex difference in the function of this subset of POMC neurons was identified with regard to energy expenditure. We reveal that a large sex difference in physical activity, energy expenditure and the development of obesity is driven by this subpopulation, which constitutes approximately 40% of all POMC neurons in the hypothalamic arcuate nucleus. This may have broad implications for strategies utilized to combat obesity, which at present largely ignore the sex of the obese individual.

A Comparison of New Pharmacological Agents for the Treatment of Obesity

Objective: To review and compare the phase 3 clinical trial evidence on the 4 new pharmacological agents approved for the management of overweight and obesity. Data Sources: Searches were performed (from 1966 through January 2016) in PubMed/MEDLINE, Scientific Citation Index, and product package inserts to identify key phase 3 clinical trials that were used in the approval of each agent. Study Selection and Data Extraction: Phase 3 clinical trials that listed end points of ≥5% and ≥10% weight loss benchmarks from baseline as well as total percentage of weight loss by participants were selected for the review. Data Synthesis: No head-to-head trials have been identified between these agents at this point, which limits comparisons across agents. Phentermine/topiramate ER appeared to have the best overall average weight loss from baseline as well as highest percentages of patients achieving both ≥5% and ≥10% weight loss benchmarks, followed second by naltrexone/bupropion, and then liraglutide, with lorcaserin showing the lowest rates. Phentermine/topiramate ER completion rates were highest for both treatment and placebo groups, followed by liraglutide, with lorcaserin and naltrexone/bupropion showing similar completion rates, below that of the other 2 agents. Common side effects reported differed between agents, although the most common adverse events reported were gastrointestinal in nature, with liraglutide demonstrating the highest reported rates and lorcaserin demonstrating the lowest. Conclusion: These 4 new pharmacological agents represent new options for the clinician to utilize when trying to manage the problem of obesity. No clear first-line agent has emerged, so treatment decisions should be based on patient-specific factors.

The 5-HT₂C receptor agonist, lorcaserin, and the 5-HT₆ receptor antagonist, SB-742457, promote satiety; a microstructural analysis of feeding behaviour

RATIONALE

Whilst the FDA-approved anorectic, lorcaserin and various 5-hydroxytryptamine (5-HT)6 receptor antagonists reduce feeding, a direct assessment of their impact upon feeding behaviour is less clear. We therefore examined the action of lorcaserin and the clinical-stage developmental candidate 5-HT6 receptor antagonist, SB-742457, upon microstructural analysis of licking behaviour. Such analysis provides a rich source of information about the mechanisms controlling food intake.

OBJECTIVES

The objective of the present study was to gain insight into the influence upon feeding behaviour of the 5-HT2C receptor agonist, lorcaserin and the developmental 5-HT6 receptor antagonist, SB-742457.

METHODS

The impact of lorcaserin and SB-742457 upon licking behaviour of non-deprived rats for a glucose solution was assessed using microstructural analysis.

RESULTS

Lorcaserin (0.1-3.0 mg/kg) displayed a dose-dependent ability to reduce glucose consumption via reduction in the number of bouts of licking. A similar action was evident with SB-742457, but only at the lowest dose tested (3.0 mg/kg).

CONCLUSIONS

The behavioural actions of both lorcaserin and SB-742457 demonstrate they directly promote satiety.

Peripheral Serotonin: a New Player in Systemic Energy Homeostasis

Whole body energy balance is achieved through the coordinated regulation of energy intake and energy expenditure in various tissues including liver, muscle and adipose tissues. A positive energy imbalance by excessive energy intake or insufficient energy expenditure results in obesity and related metabolic diseases. Although there have been many obesity treatment trials aimed at the reduction of energy intake, these strategies have achieved only limited success because of their associated adverse effects. An ancient neurotransmitter, serotonin is among those traditional pharmacological targets for anti-obesity treatment because it exhibits strong anorectic effect in the brain. However, recent studies suggest the new functions of peripheral serotonin in energy homeostasis ranging from the endocrine regulation by gut-derived serotonin to the autocrine/paracrine regulation by adipocyte-derived serotonin. Here, we discuss the role of serotonin in the regulation of energy homeostasis and introduce peripheral serotonin as a possible target for anti-obesity treatment.

Lorcaserin Hcl for the treatment of obesity

INTRODUCTION

Obesity is a major health priority necessitating safe and effective strategies to address the obesity epidemic. Lorcaserin is a serotonergic agonist specific to the 5HT- 2C receptor approved for chronic management of obesity in patients with a BMI ≥ 30 kg/m(2) or a BMI ≥ 27 kg/m(2) with comorbidities related to obesity.

AREAS COVERED

In this paper, the pharmacodynamic and pharmacokinetic properties of lorcaserin are reviewed followed by a discussion of efficacy and safety data from major clinical trials.

EXPERT OPINION

Lorcaserin is a unique highly selective serotonergic agonist designed to mitigate the risks associated with previous agents in this class. At therapeutic doses, it is well tolerated and produces modest but clinically meaningful weight loss with significant improvement in cardiometabolic parameters. Therapeutic efficacy should be assessed at 12 weeks (≥ 5% weight loss) to identify responders who will derive maximum weight loss and metabolic benefit from long-term therapy. The results of the ongoing cardiovascular outcomes trial (CAMELLIA TIMI 61) will determine the role of lorcaserin in primary prevention of diabetes in overweight/obese individuals and its use in the high-risk population of patients with established cardiovascular disease or multiple cardiovascular risk factors.

Ghrelin's Orexigenic Effect Is Modulated via a Serotonin 2C Receptor Interaction

Understanding the intricate pathways that modulate appetite and subsequent food intake is of particular importance considering the rise in the incidence of obesity across the globe. The serotonergic system, specifically the 5-HT2C receptor, has been shown to be of critical importance in the regulation of appetite and satiety. The GHS-R1a receptor is another key receptor that is well-known for its role in the homeostatic control of food intake and energy balance. We recently showed compelling evidence for an interaction between the GHS-R1a receptor and the 5-HT2C receptor in an in vitro cell line system heterologously expressing both receptors. Here, we investigated this interaction further. First, we show that the GHS-R1a/5-HT2C dimer-induced attenuation of calcium signaling is not due to coupling to GαS, as no increase in cAMP signaling is observed. Next, flow cytometry fluorescence resonance energy transfer (fcFRET) is used to further demonstrate the direct interaction between the GHS-R1a receptor and 5-HT2C receptor. In addition, we demonstrate colocalized expression of the 5-HT2C and GHS-R1a receptor in cultured primary hypothalamic and hippocampal rat neurons, supporting the biological relevance of a physiological interaction. Furthermore, we demonstrate that when 5-HT2C receptor signaling is blocked ghrelin's orexigenic effect is potentiated in vivo. In contrast, the specific 5-HT2C receptor agonist lorcaserin, recently approved for the treatment of obesity, attenuates ghrelin-induced food intake. This underscores the biological significance of our in vitro findings of 5-HT2C receptor-mediated attenuation of GHS-R1a receptor activity. Together, this study demonstrates, for the first time, that the GHS-R1a/5-HT2C receptor interaction translates into a biologically significant modulation of ghrelin's orexigenic effect. This data highlights the potential development of a combined GHS-R1a and 5-HT2C receptor treatment strategy in weight management.

5-hydroxytryptamine medications for the treatment of obesity

The central 5-hydroxytryptamine (5-HT; serotonin) system represents a fundamental component of the brain's control of energy homeostasis. Medications targeting the 5-HT pathway have been at the forefront of obesity treatment for the past 15 years. Pharmacological agents targeting 5-HT receptors (5-HTR), in combination with genetic models of 5-HTR manipulation, have uncovered a role for specific 5-HTRs in energy balance and reveal the 5-HT2 C R as the principal 5-HTR mediating this homeostatic process. Capitalising on this neurophysiological machinery, 5-HT2 C R agonists improve obesity and glycaemic control in patient populations. The underlying therapeutic mechanism has been probed using model systems and appears to be achieved primarily through 5-HT2 C R modulation of the brain melanocortin circuit via activation of pro-opiomelanocortin neurones signalling at melanocortin4 receptors. Thus, 5-HT2 C R agonists offer a means to improve obesity and type 2 diabetes, which are conditions that now represent global challenges to human health.

Neural control of energy balance: translating circuits to therapies

Recent insights into the neural circuits controlling energy balance and glucose homeostasis have rekindled the hope for development of novel treatments for obesity and diabetes. However, many therapies contribute relatively modest beneficial gains with accompanying side effects, and the mechanisms of action for other interventions remain undefined. This Review summarizes current knowledge linking the neural circuits regulating energy and glucose balance with current and potential pharmacotherapeutic and surgical interventions for the treatment of obesity and diabetes.

Tolerability and safety of the new anti-obesity medications

Worldwide obesity prevalence has nearly doubled since 1980. Due to numerous co-morbidities, obesity represents a serious health and socioeconomic problem worldwide. Pharmacotherapy should be an integral part of comprehensive obesity management. Drug therapy can assist in weight loss and its maintenance in those individuals who do not achieve appropriate weight loss through lifestyle interventions alone. After the withdrawal of sibutramine from the market in 2010, orlistat, a lipase inhibitor, was the only remaining prescription drug approved for the long-term treatment of obesity. In 2012, phentermine/topiramate extended-release (PHEN/TPM ER) combination and lorcaserin were approved by the US FDA as novel medications for long-term weight management. Three major phase III trials conducted with each drug confirmed their efficacy in terms of weight loss/maintenance and improvement of cardiometabolic risks. No head-to-head studies between the two new anti-obesity drugs have been carried out. However, in the existing studies PHEN/TPM ER had a superior weight loss profile to lorcaserin but the incidence of adverse effects was lower with lorcaserin. Both drugs were well-tolerated, and adverse events were modest in intensity, dose dependent, rather rare, and tended to decrease with the duration of treatment. Major safety concerns regarding PHEN/TPM ER include elevations in resting pulse rate, teratogenicity, mild metabolic acidosis, and psychiatric and cognitive adverse events. Valvulopathy, cognitive impairment, psychiatric disorders, and hypoglycemia represent major safety concerns for lorcaserin. Although existing trials have not demonstrated any significant issues with PHEN/TPM ER-induced heart rate elevation and lorcaserin-induced valvulopathy, all safety concerns should be seriously taken into account in patients treated with either of these novel anti-obesity medications.

Characterization of the 5-HT2C receptor agonist lorcaserin on efficacy and safety measures in a rat model of diet-induced obesity

The 5-HT2C receptor agonist lorcaserin (Belviq®) has been Food and Drug Administration (FDA) approved for the treatment of obesity. The present study is a back translational investigation into the effect of 28-day lorcaserin treatment in a diet-induced obesity (DIO) model using male, Sprague-Dawley rats. An assessment of drug effect on efficacy and multiple safety endpoints including cardiac function was undertaken. Lorcaserin (1-2 mg/kg SC b.i.d.) significantly reduced percentage body weight gain compared to vehicle-treated controls (VEH: 10.6 ± 0.4%; LOR 1: 7.6 ± 1.2%; LOR 2: 5.4 ± 0.6%). Measurement of body composition using quantitative magnetic resonance (QMR) imaging indicated this change was due to the selective reduction in body fat mass. Modest effects on food intake were recorded. At the completion of the treatment phase, echocardiography revealed no evidence for valvulopathy, that is, no aortic or mitral valve regurgitation. The pharmacokinetics of the present treatment regimen was determined over a 7-day treatment period; plasma C min and C max were in the range 13-160 ng/mL (1 mg/kg b.i.d.) and 34-264 ng/mL (2 mg/kg b.i.d.) with no evidence for drug accumulation. In sum, these studies show an effect of lorcaserin in the DIO model, that in the context of the primary endpoint measure of % body weight change was similar to that reported clinically (i.e., 3.0-5.2% vs. 3.2%). The present studies highlight the translational value of obesity models such as DIO, and suggest that assuming consideration is paid to nonspecific drug effects such as malaise, the DIO model has reasonable forward translational value to help predict clinical outcomes of a new chemical entity.

Bariatric endocrinology: principles of medical practice

Obesity, is a chronic, biological, preventable, and treatable disease. The accumulation of fat mass causes physical changes (adiposity), metabolic and hormonal changes due to adipose tissue dysfunction (adiposopathy), and psychological changes. Bariatric endocrinology was conceived from the need to address the neuro-endocrinological derangements that are associated with adiposopathy, and from the need to broaden the scope of the management of its complications. In addition to the well-established metabolic complications of overweight and obesity, adiposopathy leads to hyperinsulinemia, hyperleptinemia, hypoadiponectinemia, dysregulation of gut peptides including GLP-1 and ghrelin, the development of an inflammatory milieu, and the strong risk of vascular disease. Therapy for adiposopathy hinges on effectively lowering the ratio of orexigenic to anorexigenic signals reaching the the hypothalamus and other relevant brain regions, favoring a lower caloric intake. Adiposopathy, overweight and obesity should be treated indefinitely with the specific aims to reduce fat mass for the adiposity complications, and to normalize adipose tissue function for the adiposopathic complications. This paper defines the principles of medical practice in bariatric endocrinology-the treatment of overweight and obesity as means to treat adiposopathy and its accompanying metabolic and hormonal derangements.

Novel metabolic drugs and blood pressure: implications for the treatment of obese hypertensive patients?

Hypertension and obesity often coexist, exposing patients to cardiovascular and metabolic risks, particularly type 2 diabetes mellitus. Moreover, obesity may render hypertensive patients treatment resistant. We review how drugs recently approved for obesity or type 2 diabetes mellitus treatment affect blood pressure. The weight-reducing drug lorcaserin induces modest reductions in body weight while slightly improving blood pressure. The fixed low-dose topiramate/phentermine combinations elicit larger reductions in body weight and blood pressure. Concomitant improvements in glucose metabolism, adiposity, and blood pressure differentiate the first clinically available SGLT2 inhibitor dapagliflozin from other oral antidiabetic drugs. Yet, the mechanisms through which metabolic drugs affect blood pressure and their interaction with antihypertensive drugs are poorly understood. Blood pressure-lowering effects of metabolic drugs could be exploited in the clinical management of obese hypertensive patients with and without type 2 diabetes mellitus, particularly in patients with difficult to control arterial hypertension.

Lorcaserin: A novel antiobesity drug

Obesity is a major co-morbidity with hypertension and diabetes mellitus. There are few drugs for treatment of obesity like orlistat and recentlty approved drug lorcaserin. Lorcaserin has serotonergic properties and acts as an anorectic. It may cause serious side effects, including serotonin syndrome, particularly when taken with certain medicines that increase serotonin levels or activate serotonin receptors. Although, mainstay and first line of approach of treatment will always remain in having low calorie diet and increase in physical activity. Lorcaserin has come as a new hope to achieve success in treating obese patients but still a long road with further extensive research to be undertaken in the treatment of obesity.

An evolving scientific basis for the prevention and treatment of pediatric obesity

The 2013 Pennington Biomedical Research Center's Scientific Symposium focused on the treatment and management of pediatric obesity and was designed to (i) review recent scientific advances in the prevention, clinical treatment and management of pediatric obesity, (ii) integrate the latest published and unpublished findings and (iii) explore how these advances can be integrated into clinical and public health approaches. The symposium provided an overview of important new advances in the field, which led to several recommendations for incorporating the scientific evidence into practice. The science presented covered a range of topics related to pediatric obesity, including the role of genetic differences, epigenetic events influenced by in utero development, pre-pregnancy maternal obesity status, maternal nutrition and maternal weight gain on developmental programming of adiposity in offspring. Finally, the relative merits of a range of various behavioral approaches targeted at pediatric obesity were covered, together with the specific roles of pharmacotherapy and bariatric surgery in pediatric populations. In summary, pediatric obesity is a very challenging problem that is unprecedented in evolutionary terms; one which has the capacity to negate many of the health benefits that have contributed to the increased longevity observed in the developed world.

Update on obesity pharmacotherapy

There are two groups of approved drugs that can be used to manage weight in patients with obesity: medications approved for obesity per se and medications that affect body weight for obese patients who have complications from their obesity and are receiving these medications for chronic disease management. For obesity per se, treatment is with one of the three drugs currently approved for long-term treatment of obesity or one of a few others that can be used for short-term treatment. Among these, orlistat partially blocks intestinal digestion of fat and produces weight loss of 5-8 kg but major limitations are associated gastrointestinal symptoms; lorcaserin, a serotonin-2C agonist with few side effects, produces a mean weight loss of 4-7 kg; and the combination of phentermine and topiramate (extended release) produces a mean weight loss of 8-10 kg, but should only be used after verifying a woman is not pregnant. Failure to lose more than 3% of body weight within 3 months with any of these agents should lead to reevaluation of therapy. The short-term drugs for treating obesity per se are sympathomimetics, with phentermine being most widely used. The second group of drugs is for weight-centric prescribing for patients with a chronic disease such as diabetes, depression, or psychiatric disorders. For each disorder, some drugs produce weight gain, others are weight neutral, but the best choice for these patients is the combination of drugs that treat the underlying condition and also produce weight loss.

Lorcaserin and pimavanserin: emerging selectivity of serotonin receptor subtype-targeted drugs

Serotonin (5-hydroxytryptamine, or 5-HT) receptors mediate a plethora of physiological phenomena in the brain and the periphery. Additionally, serotonergic dysfunction has been implicated in nearly every neuropsychiatric disorder. The effects of serotonin are mediated by fourteen GPCRs. Both the therapeutic actions and side effects of commonly prescribed drugs are frequently due to nonspecific actions on various 5-HT receptor subtypes. For more than 20 years, the search for clinically efficacious drugs that selectively target 5-HT receptor subtypes has been only occasionally successful. This review provides an overview of 5-HT receptor pharmacology and discusses two recent 5-HT receptor subtype-selective drugs, lorcaserin and pimavanserin, which target the 5HT2C and 5HT2A receptors and provide new treatments for obesity and Parkinson's disease psychosis, respectively.

Obese and overweight children and adolescents: an algorithmic clinical approach

Obesity in children and adolescents is a hot issue throughout the world. Numerous complications are related to childhood obesity, such as cardiovascular disease, diabetes, insulin resistance and psychological problems. Therefore, identification and treatment of this problem have an important role in the health system. In this clinical approach, we have provided a general overview of the assessment and management of obesity in children and adolescents, including definitions, history-taking, physical examinations, and laboratory testing for general practitioners and pediatricians. Furthermore, conventional therapies (physical activity, eating habits and behavioral modification) and non-conventional treatments (drugs and surgery options) have been discussed.

Lorcaserin: a novel serotonin 2C agonist for the treatment of obesity

BACKGROUND

Obesity has become an epidemic in the United States and its prevalence continues to increase. Adjunctive treatment with pharmacotherapy is often reserved for individuals who fail to achieve their intended weight goals with diet and exercise alone. Current approved therapies for weight loss include phentermine, diethylpropion, orlistat, and phentermine/topiramate. The objective of this paper was to review the place of lorcaserin, a novel serotonin 2C agonist, which was FDA approved in July 2012. Unlike contemporary lipase inhibitors and sympathomimetic amines, lorcaserin is purported to reduce food consumption and increase satiety.

SCOPE

A systematic review of the literature for all relevant articles was performed through January 2013 using MEDLINE, Web of Science, and International Pharmaceutical Abstracts using key words related to lorcaserin.

FINDINGS

Three phase III clinical studies have been published evaluating the efficacy and safety of lorcaserin in various obese populations. A higher proportion of patients receiving lorcaserin (∼47%) lost more than 5% body weight from baseline in comparison with the placebo group (∼25%; p < 0.05 in all studies). Those receiving the recommended dose of lorcaserin 10 mg twice daily lost on average ∼6 kg of body weight from baseline versus ∼3 kg with placebo. Patients with diabetes mellitus also saw significant reductions in their HbA1c with lorcaserin (∼0.9%) versus placebo (∼0.4%; p < 0.001). Lorcaserin is generally well tolerated with the most commonly experienced adverse events being nausea, dizziness, headache, upper respiratory tract infections, and nasopharyngitis. Cardiovascular evaluations showed no appreciable increase in valvulopathy with lorcaserin use versus placebo.

CONCLUSION

For now, pharmacists should continue to recommend the use of lorcaserin as a complement to, not in lieu of, ongoing lifestyle and behavioral modification.

Efficacy and safety of lorcaserin in obese adults: a meta-analysis of 1-year randomized controlled trials (RCTs) and narrative review on short-term RCTs

Lorcaserin is a new anti-obesity drug recently approved by US Food and Drug Administration. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the association of lorcaserin therapy with weight loss and adverse events in obese adults (18-65 years old). Weight loss of 3.23 kg (95% confidence interval [CI]: 2.70, 3.75) and body mass index reduction of 1.16 kg m⁻² (95% CI: 0.98, 1.34) was observed compared with placebo in RCTs of 1 year duration. The use of lorcaserin for 8 and 12 weeks reduced weight of 1.60 kg (95% CI: 0.34, 2.86) and 2.9 kg (95% CI: 2.2, 3.5), respectively. In comparison to placebo, lorcaserin decreased waist circumference, blood pressure, total cholesterol, low-density lipoprotein-cholesterol and triglycerides, however did not statistically affect heart rate or high-density lipoprotein-cholesterol. Headache, nausea and dizziness were found to be significantly higher in the patients receiving lorcaserin than patients receiving placebo, whereas diarrhoea is no more likely than in patients receiving placebo. In conclusion, lorcaserin achieves modest weight loss and appears to be well tolerated. Clinical and pharmacovigilance studies with longer study duration are needed to inform of the long-term efficacy and safety of lorcaserin.

Drug updates and approvals: 2012 in review

Each year, the FDA approves many pharmaceuticals and products designed to treat or improve a patient's condition. The following is a sampling of some of the most important drugs approved in 2012 that specifically apply to nurse practitioner practice.

Lipoprotein subfractions in metabolic syndrome and obesity: clinical significance and therapeutic approaches

Small, dense low density lipoprotein (sdLDL) represents an emerging cardiovascular risk factor, since these particles can be associated with cardiovascular disease (CVD) independently of established risk factors, including plasma lipids. Obese subjects frequently have atherogenic dyslipidaemia, including elevated sdLDL levels, in addition to elevated triglycerides (TG), very low density lipoprotein (VLDL) and apolipoprotein-B, as well as decreased high density lipoprotein cholesterol (HDL-C) levels. Obesity-related co-morbidities, such as metabolic syndrome (MetS) are also characterized by dyslipidaemia. Therefore, agents that favourably modulate LDL subclasses may be of clinical value in these subjects. Statins are the lipid-lowering drug of choice. Also, anti-obesity and lipid lowering drugs other than statins could be useful in these patients. However, the effects of anti-obesity drugs on CVD risk factors remain unclear. We review the clinical significance of sdLDL in being overweight and obesity, as well as the efficacy of anti-obesity drugs on LDL subfractions in these individuals; a short comment on HDL subclasses is also included. Our literature search was based on PubMed and Scopus listings. Further research is required to fully explore both the significance of sdLDL and the efficacy of anti-obesity drugs on LDL subfractions in being overweight, obesity and MetS. Improving the lipoprotein profile in these patients may represent an efficient approach for reducing cardiovascular risk.

Lipoprotein subfractions in metabolic syndrome and obesity: clinical significance and therapeutic approaches

Small, dense low density lipoprotein (sdLDL) represents an emerging cardiovascular risk factor, since these particles can be associated with cardiovascular disease (CVD) independently of established risk factors, including plasma lipids. Obese subjects frequently have atherogenic dyslipidaemia, including elevated sdLDL levels, in addition to elevated triglycerides (TG), very low density lipoprotein (VLDL) and apolipoprotein-B, as well as decreased high density lipoprotein cholesterol (HDL-C) levels. Obesity-related co-morbidities, such as metabolic syndrome (MetS) are also characterized by dyslipidaemia. Therefore, agents that favourably modulate LDL subclasses may be of clinical value in these subjects. Statins are the lipid-lowering drug of choice. Also, anti-obesity and lipid lowering drugs other than statins could be useful in these patients. However, the effects of anti-obesity drugs on CVD risk factors remain unclear. We review the clinical significance of sdLDL in being overweight and obesity, as well as the efficacy of anti-obesity drugs on LDL subfractions in these individuals; a short comment on HDL subclasses is also included. Our literature search was based on PubMed and Scopus listings. Further research is required to fully explore both the significance of sdLDL and the efficacy of anti-obesity drugs on LDL subfractions in being overweight, obesity and MetS. Improving the lipoprotein profile in these patients may represent an efficient approach for reducing cardiovascular risk.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

Pharmacotherapy for childhood obesity: present and future prospects

Pediatric obesity is a serious medical condition associated with significant comorbidities during childhood and adulthood. Lifestyle modifications are essential for treating children with obesity, yet many have insufficient response to improve health with behavioral approaches alone. This review summarizes the relatively sparse data on pharmacotherapy for pediatric obesity and presents information on obesity medications in development. Most previously studied medications demonstrated, at best, modest effects on body weight and obesity-related conditions. It is to be hoped that the future will bring new drugs targeting specific obesity phenotypes that will allow clinicians to use etiology-specific, and therefore more effective, anti-obesity therapies.

Lorcaserin Hydrochloride

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. Subscribers to The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X.). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The November 2012 monograph topics are on vincristine sulfate liposome injection; ZIV-aflibercept; icosapent ethyl; prednisone delayed-release tablets; and elvitegravir, cobicistat, emtricitabine, tenofovir DF. The DUE/MUE is on vincristine sulfate liposome.

Aripiprazole partial agonism at 5-HT2C: a comparison of weight gain associated with aripiprazole adjunctive to antidepressants with high versus low serotonergic activities

OBJECTIVE

5-HT2C receptor antagonists are thought to contribute toward increased appetite and obesity. Aripiprazole acts as a partial agonist at the 5-HT2C receptor; hence, it is thought to cause little or no significant weight gain when used alone. We theorize that, in the presence of antidepressants with high serotonergic activity, aripiprazole acts as an antagonist at the 5-HT2C receptor, thus increasing the potential for weight gain. Conversely, in environments with low serotonergic activity, aripiprazole acts as an agonist at the 5-HT2C receptor, therefore having less potential for weight gain.

METHOD

A retrospective electronic medical record chart review of the Veterans Integrated Service Network 22 Veterans Affairs database was performed comparing patients' weight and body mass index (BMI) while taking aripiprazole alone (n = 1,177), versus aripiprazole plus a high-serotonergic antidepressant (citalopram, fluoxetine, paroxetine, sertraline, or venlafaxine) (n = 145), versus aripiprazole plus a low-serotonergic antidepressant (bupropion) (n = 77) for a minimum continuous duration of 6 months of aripiprazole monotherapy or combination treatment. The study was conducted from January 2010 through June 2011.

RESULTS

In our patient population, only the aripiprazole plus high-serotonergic antidepressants group had a statistically significant increase in weight (P = .0027) and BMI (P = .0016).

CONCLUSIONS

Our data suggest that, in the presence of antidepressants with high serotonergic activity, aripiprazole may act as an antagonist at the 5-HT2C receptor, resulting in weight gain. Conversely, when aripiprazole is used in the presence of antidepressants with low serotonergic activity, it may act as an agonist and result in little or no weight gain. This varying effect at the 5-HT2C receptor may explain why aripiprazole has not been associated with significant weight gain in previous studies focusing on schizophrenia and bipolar disorder.

Pharmacotherapeutic Options for the Treatment of Patients with Obesity

Objective:

To assess the safety and efficacy of FDA-approved and in-development antiobesity agents.

Data Sources:

Literature was accessed through MEDLINE (1950-current) and EMBASE using the terms antiobesity agent, diethylpropion, phentermine, orlistat, topiramate, lorcaserin, bupropion, and naltrexone. In addition, reference citations from publications identified were reviewed. Files related to FDA expert panel hearings were retrieved from the FDA website.

Study Selection and Data Extraction:

Randomized double-blind trials assessing the efficacy and safety of antiobesity agents compared with placebo in the treatment of overweight and obese adults were reviewed. Only English-language or English-translated literature was reviewed. Medications were selected based on FDA approval status.

Data Synthesis:

Ten double-blind clinical trials were reviewed. There are currently 5 FDA-approved antiobesity agents and 1 agent recently rejected by the FDA. Study results for all agents showed statistically significant weight loss compared with placebo, but with varying adverse effects. The combination of phentermine and topiramate is the most efficacious antiobesity agent approved by the FDA. However, this combination has various neurologic, cardiovascular, and teratogenic safety risks that may limit its use. Based on its safety profile, orlistat is the preferred antiobesity medication, despite the lesser extent to which it induces weight loss versus newer agents. The incidence of unwanted gastrointestinal adverse effects limits its use.

Conclusions:

Despite a glaring medical need for options to treat obesity, available medications are limited. No current drug option is ideal; each has either safety risks or efficacy concerns. Safe agents that meet FDA efficacy standards are needed to help treat the obesity epidemic.

Serotonergic anti-obesity agents: past experience and future prospects

The role of serotonin (5-hydroxytryptamine) in appetite control is long established. Serotonergic manipulations reduce food intake in rodents in a manner consistent with satiety. In humans, drugs such as fenfluramine, dexfenfluramine and sibutramine all reduce energy intake, suppress hunger and enhance satiety. Effects on eating behaviour and subjective sensations of appetite are associated with the weight loss-inducing effects of these treatments. Currently, no appetite-suppressing drugs are approved specifically for the treatment of obesity. However, a new generation of serotonergic drugs have progressed through clinical development. The serotonin 5-HT(2C)-receptor selective agonist lorcaserin, a drug specifically developed to target satiety without producing the side effect profiles of its predecessors, has been shown to significantly reduce energy intake and body weight. The weight loss produced by lorcaserin appears modest, and behavioural effects, particularly its supposed satiety-enhancing effects, have yet to be characterized. The monoaminergic re-uptake inhibitor tesofensine has also been shown to produce impressive weight loss in smaller-scale clinical studies. It remains unclear if this drug produces any effects on appetite mediated by serotonin, or whether weight loss is produced largely through enhanced energy expenditure. Evidence indicates that tesofensine strengthens satiety, but behavioural specificity and psychological side effects remain an issue. The serotonergic system remains a viable target for anti-obesity treatment. In this review, we examine the limited behavioural data available on these two new CNS-acting appetite suppressants.