Understanding the Mechanism of Action and Clinical Implications of Anti-Obesity Drugs Recently Approved in Korea

Comparison of the Efficacy of Anti-Obesity Medications in Real-World Practice

Purpose

Anti-obesity medications (AOMs), along with lifestyle interventions, are effective means of inducing and maintaining weight loss in patients with obesity. Although the efficacy of AOMs has been reported, there have been no direct comparisons of these drugs. Therefore, in the present study, we aimed to compare the efficacy of all the AOMs available in Korea in a real-world setting.

Patients and Methods

The body weight and composition of 205 adults treated with phentermine, phentermine/topiramate, liraglutide, naltrexone/bupropion, lorcaserin, or orlistat for at least 6 months were analyzed at 2 month intervals. The prevalence of the achievement of a ≥5% weight loss and the changes in body composition were compared between participants using each AOM at each visit.

Results

A total of 132 (64.4%) participants achieved ≥5% weight loss within 6 months (prevalence of ≥5% weight loss after 6 months: phentermine, 87.2%; phentermine/topiramate, 67.7%; liraglutide, 58.1%; naltrexone/bupropion, 35.3%; lorcaserin, 75%; orlistat, 50%). At each visit, after adjustment for age, sex, and baseline body weight, phentermine use was associated with a significantly higher prevalence of ≥5% weight loss than the use of the other AOMs, except for liraglutide. There were significant differences in the body weight, body mass index and body fat mass among the AOM groups by visit (P for interaction <0.05), but not in their waist circumference, skeletal muscle mass, percentage body fat, or visceral fat area.

Conclusion

All the AOMs were effective at inducing and maintaining weight loss, in the absence of significant changes in muscle mass, over a 6 month period, and the short-term use of phentermine and the long-term use of phentermine/topiramate or liraglutide would be practical choices for the treatment of obesity. However, further, large-scale studies are necessary to confirm these findings.

Visceral adipose tissue and residual cardiovascular risk: a pathological link and new therapeutic options

Obesity is a heterogeneous disease that affects almost one-third of the global population. A clear association has been established between obesity and cardiovascular disease (CVD). However, CVD risk is known to be related more to the local distribution of fat than to total body fat. Visceral adipose tissue (VAT) in particular has a high impact on CVD risk. This manuscript reviews the role of VAT in residual CV risk and the available therapeutic strategies for decreasing residual CV risk related to VAT accumulation. Among the many pathways involved in residual CV risk, obesity and particularly VAT accumulation play a major role by generating low-grade systemic inflammation, which in turn has a high prognostic impact on all-cause mortality and myocardial infarction. In recent years, many therapeutic approaches have been developed to reduce body weight. Orlistat was shown to reduce both weight and VAT but has low tolerability and many drug-drug interactions. Naltrexone-bupropion combination lowers body weight but has frequent side effects and is contraindicated in patients with uncontrolled hypertension. Liraglutide and semaglutide, glucagon-like peptide 1 (GLP-1) agonists, are the latest drugs approved for the treatment of obesity, and both have been shown to induce significant body weight loss. Liraglutide, semaglutide and other GLP-1 agonists also showed a positive effect on CV outcomes in diabetic patients. In addition, liraglutide showed to specifically reduce VAT and inflammatory biomarkers in obese patients without diabetes. GLP-1 agonists are promising compounds to limit inflammation in human visceral adipocytes.

360-Degree Perspectives on Obesity

Alarming statistics show that the number of people affected by excessive weight has surpassed 2 billion, representing approximately 30% of the world's population. The aim of this review is to provide a comprehensive overview of one of the most serious public health problems, considering that obesity requires an integrative approach that takes into account its complex etiology, including genetic, environmental, and lifestyle factors. Only an understanding of the connections between the many contributors to obesity and the synergy between treatment interventions can ensure satisfactory outcomes in reducing obesity. Mechanisms such as oxidative stress, chronic inflammation, and dysbiosis play a crucial role in the pathogenesis of obesity and its associated complications. Compounding factors such as the deleterious effects of stress, the novel challenge posed by the obesogenic digital (food) environment, and the stigma associated with obesity should not be overlooked. Preclinical research in animal models has been instrumental in elucidating these mechanisms, and translation into clinical practice has provided promising therapeutic options, including epigenetic approaches, pharmacotherapy, and bariatric surgery. However, more studies are necessary to discover new compounds that target key metabolic pathways, innovative ways to deliver the drugs, the optimal combinations of lifestyle interventions with allopathic treatments, and, last but not least, emerging biological markers for effective monitoring. With each passing day, the obesity crisis tightens its grip, threatening not only individual lives but also burdening healthcare systems and societies at large. It is high time we took action as we confront the urgent imperative to address this escalating global health challenge head-on.

FDA-Approved Pharmacotherapy for Weight Loss Over the Last Decade

Obesity is a recently defined illness whose diagnosis and treatment continue to be stigmatized. Currently, due to lifestyle changes brought on by technological advancements and the wide availability and affordability of high-calorie foods, millions of people around the world suffer from obesity and/or its sequelae. Finding adequate prevention and treatment options would therefore lead to massive improvements in the duration and quality of life of affected individuals. In this review, we searched the PubMed database for studies exploring the safety and efficacy of the five medications currently approved by the FDA for the treatment of obesity. We included only studies pertaining to adult patients that have been published between 2012 and 2022. We found evidence that all the drugs analyzed such as orlistat, phentermine/topiramate, naltrexone/bupropion, liraglutide, and semaglutide appear to be effective in inducing weight loss, with the suggestion that semaglutide may have superior efficacy. However, a massive obstacle in developing treatment guidelines remains the lack of prolonged studies monitoring the long-term safety and efficacy of obesity medications. Nevertheless, in patients at risk of complications from obesity, the benefits of losing fat mass may outweigh the potential side effects associated with these medications and clinicians should prescribe whichever of the FDA-approved pharmacotherapy they deem most appropriate for the patient’s specific set of circumstances.

Pharmacotherapy in obesity: the current state and the near future

Background: In Korea, the prevalence of obesity, morbid obesity with serious complications, and childhood obesity are rapidly increasing. To control the obesity pandemic, both prevention and treatment are essential strategic targets. While lifestyle modification is fundamental in obesity treatment, due to the complex appetite-controlling system in the body and the rapidly Westernizing environment, more effective treatment tools are required.Current Concepts: There are 4 types of drugs that have been approved for the treatment of obesity in Korea. They are (1) appetite suppressants for short-term therapy, (2) dietary fat absorption inhibitors, (3) glucagon-like peptide-1 (GLP-1) receptor agonists, and (4) fixed-dose combination drugs for appetite control. However, a large amount of weight reduction cannot be achieved with these drugs. The greatest amount of weight reduction of approximately 11% has been reported for phentermine/topiramate combination treatment. Recently, peptide agents have been under development and 2 of these agents, semaglutide, a second generation GLP-1 receptor agonist, and tirzepatide, a glucose-dependent insulinotropic polypeptide/GLP-1 receptor dual agonist, are expected to be available in the near future.Discussion and Conclusion: Both semaglutide and tirzepatide are more effective than currently available anti-obesity drugs. Semaglutide and tirzepatide reduced the body weight of people with obesity without diabetes by 14.9% and 20.9%, respectively. However, because of the mechanism of GLP-1 receptor agonism, gastrointestinal adverse events, including nausea, diarrhea, vomiting, and abdominal pain, were problematic in many patients, although these adverse events were generally acceptable. Both drugs will be excellent options for obesity treatment in the near future.

Efficacy of subcutaneous semaglutide compared to placebo for weight loss in obese, non-diabetic adults: a systematic review & meta-analysis

BACKGROUND

Research on semaglutide's effect on weight loss has been largely focused on Type 2 Diabetics. No meta-analyses of semaglutide's efficacy in non-diabetic individuals have been conducted to date. Expanding the knowledge of semaglutide's outcome in non-diabetics may provide impactful changes at the clinical level.

AIM

This systematic review and meta-analysis quantified the efficacy of subcutaneous semaglutide in treating obesity in non-diabetic adult patients compared to placebo.

METHOD

Academic Search Premier, Cumulative Index to Nursing and Allied Health Literature (CINAHL) complete, MEDLINE with Full Text, Cochrane Central Register of Controlled Trials, medrxiv.org, and clinicaltrials.gov were systematically investigated using a predetermined search strategy from inception to August 21, 2021. Covidence.org was used to screen, select, and extract data by two independent reviewers. Individual study bias was assessed using the Cochrane Risk of Bias 2 tool. Data were exported to RevMan v5.4, where meta-analysis was conducted using a DerSimonian and Laird random-effects model.

RESULTS

The initial search identified 332 relevant articles and ultimately retained four randomized controlled trials encompassing 2,882 participants with a BMI ≥ 27 kg/m². Patients treated with semaglutide experienced a clinically significant reduction in mean body weight - 11.62 kg (95% CI: -13.03 to -10.21; P < 0.00001).

CONCLUSION

This systematic review and meta-analysis validates the clinical efficacy of semaglutide for the treatment of obesity in the adult, non-diabetic population.

AgRP/NPY and POMC neurons in the arcuate nucleus and their potential role in treatment of obesity

Obesity is a major health crisis affecting over a third of the global population. This multifactorial disease is regulated via interoceptive neural circuits in the brain, whose alteration results in excessive body weight. Certain central neuronal populations in the brain are recognised as crucial nodes in energy homeostasis; in particular, the hypothalamic arcuate nucleus (ARC) region contains two peptide microcircuits that control energy balance with antagonistic functions: agouti-related peptide/neuropeptide-Y (AgRP/NPY) signals hunger and stimulates food intake; and pro-opiomelanocortin (POMC) signals satiety and reduces food intake. These neuronal peptides levels react to energy status and integrate signals from peripheral ghrelin, leptin, and insulin to regulate feeding and energy expenditure. To manage obesity comprehensively, it is crucial to understand cellular and molecular mechanisms of information processing in ARC neurons, since these regulate energy homeostasis. Importantly, a specific strategy focusing on ARC circuits needs to be devised to assist in treating obese patients and maintaining weight loss with minimal or no side effects. The aim of this review is to elucidate the recent developments in the study of AgRP-, NPY- and POMC-producing neurons, specific to their role in controlling metabolism. The impact of ghrelin, leptin, and insulin signalling via action of these neurons is also surveyed, since they also impact energy balance through this route. Lastly, we present key proteins, targeted genes, compounds, drugs, and therapies that actively work via these neurons and could potentially be used as therapeutic targets for treating obesity conditions.

Computational Drug Repurposing Approach to Identify Potential Fatty Acid-Binding Protein-4 Inhibitors to Develop Novel Antiobesity Therapy

Obesity is a chronic human disorder caused by multiple factors, causing excessive accumulation of fat because of the disparity in take of energy intake with respect to its expenditure. Genetic, environmental, and behavioral factors are having a crucial role in its pathogenesis. Fatty acid-binding protein (FABP) is a superfamily that was involved in the transportation, metabolism, and storage of lipids. The experimental studies have revealed that there is a significant rise in the fatty acid-binding protein-4 (FABP4) expression, and plasma concentration in obese and its downregulation or inhibition can be a potential drug target for obesity. Repurposing of drugs is a trending method for the identification of the newer pharmacological action of an established drug molecule having initially approved indication. It is a cost-effective and economical approach for the development of alternative therapies for existing dreadful diseases in quick succession. Thus, the in silico drug repurposing technique is a highly effective approach for identifying an existing drug molecule having an antiobesity therapeutic activity against the human FABP4, and Floxacillin was selected as safe and effective drug for candidates for developing an antiobesity therapy.

Reducing Effect of Farnesylquinone on Lipid Mass in C. elegans by Modulating Lipid Metabolism

Bioassay-guided fractionation of marine-derived fungi revealed that the EtOAc fraction from the fermentation broth of a mutated fungal strain Streptomyces nitrosporeus YBH10-5 had lipid-lowering effects in HepG2 cells. Chromatographic separation of the EtOAc fraction resulted in the isolation of 11 PKS-based derivatives, including a structurally unique meroterpenoid namely nitrosporeunol H (1). The structure of compound 1 was determined by the analysis of spectroscopic data. Further bioassay resulted in farnesylquinone (2) and its analogues to exert in vivo fat-reducing effects in C.elegans worm model. The underlying mode of action of compound 2 in the context of live worms was investigated, uncovering that compound 2 enhanced the mitochondrial β-oxidation rate and changed the transcriptional level of energy metabolism genes. Additional experiments revealed that compound 2 exerted its effects in C. elegans partially through repressing FAT-5, an isoform of stearoyl-CoA desaturase (SCD) which catalyzes the conversion of saturated fatty acids to monounsaturated fatty acids, thereafter leading to the modification of the fatty acid profile. Thus, compound 2 was suggested to be a promising lead for further optimization to treat obesity.