Lorcaserin for weight management

Recent advancements in pharmacological strategies to modulate energy balance for combating obesity

The prevalence of obesity along with its related metabolic diseases has increased globally in recent decades. Obesity originates from a heterogeneous physiological state, which is further complicated by the influence of factors such as genetic, behavioural, and environmental. Lifestyle interventions including exercise and diet have limited success, necessitating the development of pharmacological approaches. Mechanistically, strategies target either reducing energy intake or increasing consumption through metabolism boosting. Current drugs lower energy intake via inducing satiety or inhibiting substrate absorption, while targeting mitochondria or cytosolic energy sensors has shown limited success due to toxicity. Nonshivering thermogenesis (NST) has provided hope for activating these processes selectively without significant side effects. The internet-based marketing of plant-based formulations for enhancing metabolism has surged. This review compiles scientific articles, magazines, newspapers, and online resources on anti-obesity drug development. Combination therapy of metabolic boosters and established anti-obesity compounds appears to be a promising future approach that requires further research.

Pharmacological Management of Obesity: A Century of Expert Opinions in Cecil Textbook of Medicine

BACKGROUND

Innovations in drug therapy for obesity have had a limited impact on the body mass index, prevalence of medical complications, quality of life, and work potential of a substantial majority of affected persons.

STUDY QUESTION

What are the milestones of the changes in the expert approach to the pharmacological management of obesity in the past century?

STUDY DESIGN

To determine the changes in the experts' approach to the management of obesity, as presented in a widely used textbook in the United States.

DATA SOURCES

The primary sources were chapters describing the management of obesity in the 26 editions of Cecil Textbook of Medicine published from 1927 through 2020. Secondary sources were publications retrieved from Medline that clarified technical issues related to the development, regulatory approval, and use of the drugs mentioned in the Cecil Textbook of Medicine.

RESULTS

Pharmacological interventions aimed at increasing caloric expenditures through thermogenesis were recommended from 1927 through 1943. Thyroid extracts were prescribed even in the absence of demonstrated hypothyroidism or decreased basal metabolic rate throughout this period. Dinitrophenol was mentioned in 1937, but was banned soon thereafter. Appetite suppression with amphetamine was considered useful from 1943 through 1988, after which the drug was replaced with other centrally acting molecules, such as fenfluramine in 1988, sibutramine in 2000, and rimonabant in 2008, which were in turn withdrawn because of major adverse effects. In the past decade, obesity has been treated with the appetite suppressants phentermine-topiramate, bupropion-naltrexone, lorcaserin, and liraglutide, and with orlistat, a drug promoting fat malabsorption. The change in weight produced by these drugs is generally modest and transient.

CONCLUSIONS

The pharmacological management of obesity has remained frustratingly inefficient. The reasons for the relative lack of success may reside in the ever-growing access to dense, palatable, and relatively inexpensive food, coupled with the decrease in energy expenditure created by a sedentary lifestyle.

Role of serotonin in body weight, insulin secretion and glycaemic control

Obesity and type 2 diabetes are key healthcare challenges of the 21st century. Subsequent to its discovery in 1948, serotonin (5-hydroxytryptamine; 5-HT) has emerged as a principal modulator of energy homeostasis and body weight, prompting it to be a target of weight loss medications (eg, fenfluramine, D-fenfluramine, fenfluramine-phentermine and sibutramine). The potential risk of off-target effects led to these medications being withdrawn from clinical use and spurred drug discovery into 5-HT receptor selective ligands. The serotonin 2C receptor (5-HT_2C R) is the primary receptor through which 5-HT impacts feeding and body weight and 5-HT_2C R agonist lorcaserin was released for obesity treatment in 2012. Obese patients with type 2 diabetes prescribed medications that produce weight loss commonly observe improvements in type 2 diabetes. However, recent research has provided compelling evidence that 5-HT_2C R agonists produce effects on blood glucose and insulin sensitivity independent of weight loss. As such, neuroactive 5-HT_2C R agonists are a potential new category of type 2 diabetes medications. 5-HT is also expressed within pancreatic β cells, is co-released with insulin and may have a role in modulating insulin secretion. This review highlights the latest advances in the function of 5-HT in body weight, insulin release and glycaemic control.

Long-term effects of weight-reducing drugs in people with hypertension

BACKGROUND

This is the third update of this review, first published in July 2009. All major guidelines on treatment of hypertension recommend weight loss; anti-obesity drugs may be able to help in this respect.

OBJECTIVES

Primary objectives: To assess the long-term effects of pharmacologically-induced reduction in body weight in adults with essential hypertension on all-cause mortality, cardiovascular morbidity, and adverse events (including total serious adverse events, withdrawal due to adverse events, and total non-serious adverse events).. Secondary objectives: To assess the long-term effects of pharmacologically-induced reduction in body weight in adults with essential hypertension on change from baseline in systolic and diastolic blood pressure, and on body weight reduction.

SEARCH METHODS

For this updated review, the Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to March 2020: the Cochrane Hypertension Specialised Register, CENTRAL, MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. The searches had no language restrictions. We contacted authors of relevant papers about further published and unpublished work.

SELECTION CRITERIA

Randomised controlled trials of at least 24 weeks' duration in adults with hypertension that compared approved long-term weight-loss medications to placebo.  DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies, assessed risks of bias, and extracted data. Where appropriate and in the absence of significant heterogeneity between studies (P > 0.1), we pooled studies using a fixed-effect meta-analysis. When heterogeneity was present, we used the random-effects method and investigated the cause of the heterogeneity.

MAIN RESULTS

This third update of the review added one new trial, investigating the combination of naltrexone/bupropion versus placebo. Two medications, which were included in the previous versions of this review (rimonabant and sibutramine) are no longer considered relevant for this update, since their marketing approval was withdrawn in 2010 and 2009, respectively. The number of included studies in this review update is therefore six (12,724 participants in total): four RCTs comparing orlistat to placebo, involving a total of 3132 participants with high blood pressure and a mean age of 46 to 55 years; one trial comparing phentermine/topiramate to placebo, involving 1305 participants with high blood pressure and a mean age of 53 years; and one trial comparing naltrexone/bupropion to placebo, involving 8283 participants with hypertension and a mean age of 62 years. We judged the risks of bias to be unclear for the trials investigating orlistat or naltrexone/bupropion. and low for the trial investigating phentermine/topiramate. Only the study of naltrexone/bupropion included cardiovascular mortality and morbidity as predefined outcomes. There were no differences in the rates of all-cause or cardiovascular mortality, major cardiovascular events, or serious adverse events between naltrexone/bupropion and placebo. The incidence of overall adverse events was significantly higher in participants treated with naltrexone/bupropion. For orlistat, the incidence of gastrointestinal side effects was consistently higher compared to placebo. The most frequent side effects with phentermine/topiramate were dry mouth and paraesthesia. After six to 12 months, orlistat reduced systolic blood pressure compared to placebo by mean difference (MD) -2.6 mm Hg (95% confidence interval (CI) -3.8 to -1.4 mm Hg; 4 trials, 2058 participants) and diastolic blood pressure by MD -2.0 mm Hg (95% CI -2.7 to -1.2 mm Hg; 4 trials, 2058 participants). After 13 months of follow-up, phentermine/topiramate decreased systolic blood pressure compared to placebo by -2.0 to -4.2 mm Hg (1 trial, 1030 participants) (depending on drug dosage), and diastolic blood pressure by -1.3 to -1.9 mm Hg (1 trial, 1030 participants) (depending on drug dosage). There was no difference in the change in systolic or diastolic blood pressure between naltrexone/bupropion and placebo (1 trial, 8283 participants). We identified no relevant studies investigating liraglutide or lorcaserin in people with hypertension.

AUTHORS' CONCLUSIONS

In people with elevated blood pressure, orlistat, phentermine/topiramate and naltrexone/bupropion reduced body weight; the magnitude of the effect was greatest with phentermine/topiramate. In the same trials, orlistat and phentermine/topiramate, but not naltrexone/bupropion, reduced blood pressure. One RCT of naltrexone/bupropion versus placebo showed no differences in all-cause mortality or cardiovascular mortality or morbidity after two years. The European Medicines Agency refused marketing authorisation for phentermine/topiramate due to safety concerns, while for lorcaserin the application for European marketing authorisation was withdrawn due to a negative overall benefit/risk balance. In 2020 lorcaserin was also withdrawn from the US market. Two other medications (rimonabant and sibutramine) had already been withdrawn from the market in 2009 and 2010, respectively.

Pharmacologic therapy of obesity: mechanisms of action and cardiometabolic effects

Obesity is a chronic, relapsing, multifactorial disease, which has become a serious threat to public health globally, as the worldwide prevalence of obesity increases exponentially over time. It has been well established that obesity is associated with multiple adverse cardiometabolic effects. Although lifestyle changes are the first line of therapy for obesity, these are often insufficient in attaining weight loss goals. Orlistat, phentermine/topiramate, lorcaserin, naltrexone/bupropion, and liraglutide are agents that have been approved for the treatment of obesity but their effects on cardiometabolic risk factors and outcomes have not been clearly elucidated. Given the detrimental repercussions of obesity on cardiometabolic health, there is a pressing clinical need to fully understand the effects of these agents beyond weight loss alone. Certain previous weight loss drugs have been withdrawn due to safety concerns and this underlines the need for more careful assessment of the effects of the various pharmacologic agents currently used for the treatment of obesity. This review aims to provide an overview of the mechanisms, efficacy, safety and cardiometabolic effects of the currently available pharmacologic agents for weight loss.

Pharmacotherapy of obesity: Available medications and drugs under investigation

Obesity is a chronic disease with a continuously rising prevalence that currently affects more than half a billion people worldwide. Energy balance and appetite are highly regulated via central and peripheral mechanisms, and weight loss triggers a homeostatic response leading to weight regain. Lifestyle and behavioral modifications are the cornerstones of obesity management; however, they often fail to achieve or sustain long-term weight loss. Pharmacotherapy added onto lifestyle modifications results in an additional, albeit limited, weight reduction. Regardless, this weight reduction of 5-10% conveys multiple cardiovascular and metabolic benefits. In this review, evidence on the food and drug administration (FDA)-approved medications, i.e., orlistat, lorcaserin, phentermine/topiramate, liraglutide and naltrexone/bupropion, is summarized. Furthermore, anti-obesity agents in the pipeline for potential future therapeutic use are presented.

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.

Long-term effects of weight-reducing drugs in people with hypertension

BACKGROUND

All major guidelines on antihypertensive therapy recommend weight loss; anti-obesity drugs may be able to help in this respect.

PRIMARY OBJECTIVES

To assess the long-term effects of pharmacologically induced reduction in body weight in adults with essential hypertension on all-cause mortality, cardiovascular morbidity, and adverse events (including total serious adverse events, withdrawal due to adverse events, and total non-serious adverse events).

SECONDARY OBJECTIVES

To assess the long-term effects of pharmacologically induced reduction in body weight in adults with essential hypertension on change from baseline in systolic blood pressure, change from baseline in diastolic blood pressure, and body weight reduction.

SEARCH METHODS

We obtained studies using computerised searches of the Cochrane Hypertension Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid EMBASE, the clinical trials registry ClinicalTrials.gov, and from handsearches in reference lists and systematic reviews (status as of 13 April 2015).

SELECTION CRITERIA

Randomised controlled trials in hypertensive adults of at least 24 weeks' duration that compared long-term pharmacologic interventions for weight loss with placebo. 

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed risk of bias, and extracted data. Where appropriate and in the absence of significant heterogeneity between studies (P > 0.1), we pooled studies using fixed-effect meta-analysis. When heterogeneity was present, we used the random-effects method and investigated the cause of heterogeneity.

MAIN RESULTS

After updating the literature search, which was extended to include four new weight-reducing drugs, we identified one additional study of phentermine/topiramate, bringing the total number of studies to nine that compare orlistat, sibutramine, or phentermine/topiramate to placebo and thus fulfil our inclusion criteria. We identified no relevant studies investigating rimonabant, liraglutide, lorcaserin, or naltrexone/bupropion. No study included mortality and cardiovascular morbidity as predefined outcomes. Incidence of gastrointestinal side effects was consistently higher in those participants treated with orlistat versus those treated with placebo. The most frequent side effects were dry mouth, constipation, and headache with sibutramine, and dry mouth and paresthaesia with phentermine/topiramate. In participants assigned to orlistat, sibutramine, or phentermine/topiramate body weight was reduced more effectively than in participants in the usual-care/placebo groups. Orlistat reduced systolic blood pressure as compared to placebo by -2.5 mm Hg (mean difference (MD); 95% confidence interval (CI): -4.0 to -0.9 mm Hg) and diastolic blood pressure by -1.9 mm Hg (MD; 95% CI: -3.0 to -0.9 mm Hg). Sibutramine increased diastolic blood pressure compared to placebo by +3.2 mm Hg (MD; 95% CI: +1.4 to +4.9 mm Hg). The one trial that investigated phentermine/topiramate suggested it lowered blood pressure.

AUTHORS' CONCLUSIONS

In people with elevated blood pressure, orlistat and sibutramine reduced body weight to a similar degree, while phentermine/topiramate reduced body weight to a greater extent. In the same trials, orlistat and phentermine/topiramate reduced blood pressure, while sibutramine increased it. We could include no trials investigating rimonabant, liraglutide, lorcaserin, or naltrexone/bupropion in people with elevated blood pressure. Long-term trials assessing the effect of orlistat, liraglutide, lorcaserin, phentermine/topiramate, or naltrexone/bupropion on mortality and morbidity are unavailable and needed. Rimonabant and sibutramine have been withdrawn from the market, after long-term trials on mortality and morbidity have confirmed concerns about the potential severe side effects of these two drugs. The European Medicines Agency refused marketing authorisation for phentermine/topiramate due to safety concerns, while the application for European marketing authorisation for lorcaserin was withdrawn by the manufacturer after the Committee for Medicinal Products for Human Use judged the overall benefit/risk balance to be negative.

Leptin, adiponectin and serotonin levels in lean and obese dogs

Background

Serotonin (5-hydroytryptamine or 5HT) is associated with numerous behavioral and psychological factors and is a biochemical marker of mood. 5HT is involved in the hypothalamic regulation of energy consumption. 5HT controls appetite in the central nerve system (CNS) and stimulates intestinal mobility. There are few studies looking at the role of 5HT and the relationship between peripheral circulating serotonin and obesity. The aim of this study was to find any differences in leptin, adiponectin, and 5HT between lean and obese dogs and to identify correlations among these factors.

Results

Leptin, triglyceride (TG) and cholesterol levels were higher in the obese group (all p < 0.01). Adiponectin and 5HT levels were higher in the lean group compared to the obese group (p < 0.01). Leptin (r = 0.628, p < 0.01), TG (r = 0.491, p < 0.01) and cholesterol (r = 0.419, p < 0.01) were positively correlated with body condition score (BCS), and adiponectin (r = -0.446, p < 0.01) and 5HT (r = -0.490, p < 0.01) were negatively correlated with BCS. Leptin was negatively correlated with adiponectin (r = -0.294, p < 0.01) and 5HT (r = -0.343, p < 0.01). 5HT was negatively correlated with leptin (r = -0.343, p < 0.01), TG (r = -0.268, p < 0.05) and cholesterol (r = -0.357, p < 0.05).

Conclusions

5HT is an important appetite control neurotransmitter, but there are limited studies for 5HT levels related to obesity in dogs. To the best of our knowledge, this is the first study to evaluate peripheral 5HT levels in obese dogs. From this research, we can assume that 5HT may be correlated with canine obesity. Further studies will be needed to further elucidate the role of low serum 5HT levels in canine obesity.