Metabolic profiles of minimally absorbed orlistat in obese/overweight volunteers

Orlistat ameliorates lipid dysmetabolism in high-fat diet-induced mice via gut microbiota modulation

Orlistat reduces obesity by inhibiting gastrointestinal lipases, thereby blocking the absorption and accumulation of triglycerides in the intestine. It has been shown to improve lipid metabolism and alter intestinal microbial communities in animals and humans. However, the impact of Orlistat-induced changes in gut microbiota on obesity requires further investigation. In this study, we found that Orlistat significantly improved metabolic disorders, inhibited fat accumulation, and reshaped the structure of intestinal microbiota. Specifically, it reduced α diversity and increased the relative abundance of Verrucomicrobia and Akkermansia. Notably, antibiotic-induced gut microbiota depletion significantly weakened Orlistat's effect on improving metabolic disorders. Furthermore, microbiota transplanted from Orlistat-treated mice effectively alleviated lipid metabolic disorders caused by a high-fat diet. We also observed that Orlistat increased food intake in mice and inhibited the synthesis of appetite-regulating hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon (Gcg). However, antibiotic-depleted microbiota mitigated this inhibitory effect. Interestingly, although Orlistat altered the gut microbiota of mice, transplanting these microbiota did not inhibit the synthesis of appetite-regulating hormones. In summary, our results suggest that Orlistat can reshape the gut microbiota, and the altered gut microbiota works synergistically with Orlistat to improve metabolic disorders. This improvement is related to the increased abundance of Verrucomicrobia and Akkermansia.

The detrimental effects and mechanisms of Orlistat in disrupting energy homeostasis and reproduction in Daphnia magna

Orlistat (ORL) has been employed as an anti-obesity pharmaceutical for several decades. Given its low absorption rate, the majority of administered ORL is excreted into the environment with feces. It is crucial to collect scientific information regarding the possible ecological risks associated with ORL. Here, the effects of ORL on Daphnia magna were evaluated using a 21-day chronic test at concentrations of 1, 10, 100, and 1000 μg/L. We found the inhibition of feeding and swimming activities in the 100 and 1000 μg/L ORL exposed D. magna, respectively. Their digestive enzyme activities and metabolites were reduced even at 1 μg/L ORL exposure. It is noteworthy that exposure to 100 μg/L ORL induced a decrease in the reproductive capacity of D. magna, although no discernible genotoxicity was observed. To identify the toxicological mechanisms of ORL, a metabolic analysis was conducted on D. magna exposed to 1000 μg/L ORL. A comprehensive reduction in carbohydrates, lipids, and amino acids was observed, which resulted in a blockage of metabolic flux towards the TCA cycle, as evidenced by mitochondrial dysfunction. These findings substantiate the detrimental impact of ORL on D. magna and provide insights into the underlying molecular mechanisms from a metabolic perspective.

Transcriptomic Analysis of the Protective Effect of Piperine on Orlistat Hepatotoxicity in Obese Male Wistar Rats

Obesity is a risk factor for the development of noncommunicable diseases that impair the quality of life. Orlistat is one of the most widely used drugs in the management of obesity due to its accessibility and low cost. However, cases of hepatotoxicity have been reported due to the consumption of this drug. On the other hand, piperine is an alkaloid found in black pepper that has demonstrated antiobesity, antihyperlipidemic, antioxidant, prebiotic, and hepatoprotective effects. The aim of this study was to evaluate the protective effect of piperine on the toxicity of orlistat in liver tissue. Obese male rats were administered piperine (30 mg/kg), orlistat (60 mg/kg), and the orlistat-piperine combination (30 mg/kg + 60 mg/kg) daily for 6 weeks. It was observed that the orlistat-piperine treatment resulted in greater weight loss, decreased biochemical markers (lipid profile, liver enzymes, pancreatic lipase activity), and histopathological analysis showed decreased hepatic steatosis and reduction of duodenal inflammation. Transcriptomic analysis revealed that the administration of piperine with orlistat increased the expression of genes related to the beta-oxidation of fatty acids, carbohydrate metabolism, detoxification of xenobiotics, and response to oxidative stress. Therefore, the results suggest that the administration of orlistat-piperine activates signaling pathways that confer a hepatoprotective effect, reducing the toxic impact of this drug.

Orlistat for the treatment of antipsychotic-induced weight gain: an eight-week multicenter, randomized, placebo-controlled, double-blind trial

BACKGROUND

Weight gain and metabolic disorders are commonly induced by antipsychotics. Orlistat is a lipase inhibitor used for weight control. The effect of orlistat on weight gain and metabolic disturbances in people (especially women) treated with antipsychotics has not been sufficiently studied. This study aimed to investigate the efficacy of orlistat in mitigating antipsychotic-induced weight gain and abnormal glycolipid metabolism.

METHODS

Patients with schizophrenia or bipolar disorder with a weight gain ≥ 7% after taking antipsychotics were recruited. Participants were randomly allocated to two groups: one received eight weeks of orlistat (360 mg/day) and the other received a placebo. Anthropometric and fasting serum biochemical parameters were measured at baseline, week 4 and week 8.

RESULTS

Sixty individuals (orlistat:placebo = 32:28) participated in the study. After controlling for the study center, the eight-week changes in body mass index (BMI), cholesterol (CHOL), high-density lipoprotein cholesterol (HDL-CH) and low-density lipoprotein cholesterol (LDL-CH) were significantly different between the groups. According to the mixed linear models, CHOL and LDL-CH were significantly lower in the orlistat group than in the control group at week 8. The week 0-to-8 slopes of BMI, CHOL and LDL-CH were also significantly lower in the orlistat group.

CONCLUSIONS

These findings suggested that orlistat is an effective intervention for attenuating weight gain and serum lipid disturbances in antipsychotic-treated patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03451734.

Targeting fatty acid uptake and metabolism in cancer cells: A promising strategy for cancer treatment

Despite scientific development, cancer is still a fatal disease. The development of cancer is thought to be significantly influenced by fatty acids. Several mechanisms that control fatty acid absorption and metabolism are reported to be altered in cancer cells to support their survival. Cancer cells can use de novo synthesis or uptake of extracellular fatty acid if one method is restricted. This factor makes it more difficult to target one pathway while failing to treat the disease properly. Side effects may also arise if several inhibitors simultaneously target many targets. If a viable inhibitor could work on several routes, the number of negative effects might be reduced. Comparative investigations against cell viability have found several potent natural and manmade substances. In this review, we discuss the complex roles that fatty acids play in the development of tumors and the progression of cancer, newly discovered and potentially effective natural and synthetic compounds that block the uptake and metabolism of fatty acids, the adverse side effects that can occur when multiple inhibitors are used to treat cancer, and emerging therapeutic approaches.

An epithelial cell-derived metabolite tunes immunoglobulin A secretion by gut-resident plasma cells

Immunoglobulin A (IgA) secretion by plasma cells, terminally differentiated B cells residing in the intestinal lamina propria, assures microbiome homeostasis and protects the host against enteric infections. Exposure to diet-derived and commensal-derived signals provides immune cells with organizing cues that instruct their effector function and dynamically shape intestinal immune responses at the mucosal barrier. Recent data have described metabolic and microbial inputs controlling T cell and innate lymphoid cell activation in the gut; however, whether IgA-secreting lamina propria plasma cells are tuned by local stimuli is completely unknown. Although antibody secretion is considered to be imprinted during B cell differentiation and therefore largely unaffected by environmental changes, a rapid modulation of IgA levels in response to intestinal fluctuations might be beneficial to the host. In the present study, we showed that dietary cholesterol absorption and commensal recognition by duodenal intestinal epithelial cells lead to the production of oxysterols, evolutionarily conserved lipids with immunomodulatory functions. Using conditional cholesterol 25-hydroxylase deleter mouse line we demonstrated that 7α,25-dihydroxycholesterol from epithelial cells is critical to restrain IgA secretion against commensal- and pathogen-derived antigens in the gut. Intestinal plasma cells sense oxysterols via the chemoattractant receptor GPR183 and couple their tissue positioning with IgA secretion. Our findings revealed a new mechanism linking dietary cholesterol and humoral immune responses centered around plasma cell localization for efficient mucosal protection.

In vitro and in vivo local tolerability of a synergistic anti-tuberculosis drug combination intended for pulmonary delivery

A drug combination, vancomycin (VAN) plus tetrahydrolipstatin (THL), has demonstrated an effective synergistic action in vitro against Mycobacterium tuberculosis (Mtb). The poor oral bioavailability of VAN and THL and the predominant tropism of Mtb infection to the lungs make their pulmonary administration very attractive. To evaluate their local tolerability, bronchial cells, alveolar cells and monocytes were exposed to concentrations around and above their minimal inhibitory concentration (MIC). The VAN had no inhibitory activity on the tested human cell lines, even at a concentration 125 times higher than its MIC, whereas the THL, alone or in combination with VAN, presented a cytostatic action. Monolayer epithelium showed no significant irreversible damage at concentrations up to 100 times the combination MIC. BALB/cAnNRj mice exposed to concentration of 50 times the combination MIC delivered endotracheally 3 times a week for 3 weeks showed no clinical signs or significant weight loss. The increase of proinflammatory biomarkers (i.e., IL-1, IL-6, TNF-α and proportion of inflammatory cells) and cytotoxicity in bronchoalveolar lavage fluid (BALF) were non-significant. Lung histopathology did not show significant tissue damage. The VAN/THL combination at doses up to 50 times the combination MIC is found to be thus well tolerated by pulmonary route. This study is a promising result and encouraging further investigations of pulmonary administration of VAN/THL combination as dry powder for anti-tuberculosis treatment.

Arylacetamide deacetylase as a determinant of the hydrolysis and activation of abiraterone acetate in mice and humans

AIM

Abiraterone acetate for metastatic castration-resistant prostate cancer is an acetylated prodrug to be hydrolyzed to abiraterone. Abiraterone acetate is known to be hydrolyzed by pancreatic cholesterol esterase secreted into the intestinal lumen. This study aimed to investigate the possibility that arylacetamide deacetylase (AADAC) expressed in enterocytes contributes to the hydrolysis of abiraterone acetate based on its substrate preference.

MATERIALS AND METHODS

Abiraterone acetate hydrolase activity was measured using human intestinal (HIM) and liver microsomes (HLM) as well as recombinant AADAC. Correlation analysis between activity and AADAC expression was performed in 14 individual HIMs. The in vivo pharmacokinetics of abiraterone acetate was examined using wild-type and Aadac knockout mice administered abiraterone acetate with or without orlistat, a pancreatic cholesterol esterase inhibitor.

KEY FINDINGS

Recombinant AADAC showed abiraterone acetate hydrolase activity with similar Km value to HIM and HLM. The positive correlation between activity and AADAC levels in individual HIMs supported the responsibility of AADAC for abiraterone acetate hydrolysis. The area under the plasma concentration-time curve (AUC) of abiraterone after oral administration of abiraterone acetate in Aadac knockout mice was 38% lower than that in wild-type mice. The involvement of pancreatic cholesterol esterase in abiraterone formation was revealed by the decreased AUC of abiraterone by coadministration of orlistat. Orlistat potently inhibited AADAC, implying its potential as a perpetrator of drug-drug interactions.

SIGNIFICANCE

AADAC is responsible for the hydrolysis of abiraterone acetate in the intestine and liver, suggesting that concomitant use of abiraterone acetate and drugs potently inhibiting AADAC should be avoided.

Obesity: The New Global Epidemic Pharmacological Treatment, Opportunities and Limits for Personalized Therapy

BACKGROUND

The increase in global obesity rates over the past three decades has been remarkable, a true epidemic, both in developed and in developing countries. The projections, based on current trends, suggest an increase in the prevalence of obesity at 60% in adult men, 40% in adult women and 25% in children in 2050. Given the limitations of lifestyle and surgery interventions bariatric, drug therapy approaches for the treatment of obesity, therefore become important options.

AIM

The purpose of this review is a review of the literature, based on research on MEDLINE until 2019, on the possible pharmacological options in the treatment of obesity.

RESULTS

Currently, the FDA has approved several molecules for the treatment of obesity, both in monotherapy and in combination. Pharmacological monotherapies focus mainly on a single protein target and include orlistat, lorcaserin and liraglutide while the combination molecules propose a multitarget approach and include phentermine/topiramate and naltrexone/bupropion. All the approved drugs showed, in the different studies, a weight reduction of at least 5%, compared to placebo, in 52 weeks of observation. Phentermine-topiramate and liraglutide have been associated with the highest probability of at least 5% weight loss. Liraglutide and naltrexone-bupropion had the lowest rates of therapy discontinuation due to adverse events.

CONCLUSION

The drugs, associated with the standard diet and/or exercise protocols, represent a good therapeutic opportunity to allow not only weight loss but also to reduce the risk of developing diseases caused by obesity, particularly cardiovascular diseases, and to maintain the set objectives over time. However, future research on the pharmacological treatment of obesity should encourage greater personalization of therapy, given the differences in safety, efficacy and response to therapy, in the different subpopulations of patients with obesity.

Targeting lipid metabolism is an emerging strategy to enhance the efficacy of anti-HER2 therapies in HER2-positive breast cancer

De novo or acquired resistance of cancer cells to currently available Human Epidermal Growth Factor Receptor 2 (HER2) inhibitors represents a clinical challenge. Several resistance mechanisms have been identified in recent years, with lipid metabolism reprogramming, a well-established hallmark of cancer, representing the last frontier of preclinical and clinical research in this field. Fatty Acid Synthase (FASN), the key enzyme required for fatty acids (FAs) biosynthesis, is frequently overexpressed/activated in HER2-positive (HER2+) breast cancer (BC), and it crucially sustains HER2+ BC cell growth, proliferation and survival. After the synthesis of new, selective and well tolerated FASN inhibitors, clinical trials have been initiated to test if these compounds are able to re-sensitize cancer cells with acquired resistance to HER2 inhibition. More recently, the upregulation of FA uptake by cancer cells has emerged as a potentially new and targetable mechanism of resistance to anti-HER2 therapies in HER2+ BC, thus opening a new era in the field of targeting metabolic reprogramming in clinical setting. Here, we review the available preclinical and clinical evidence supporting the inhibition of FA biosynthesis and uptake in combination with anti-HER2 therapies in patients with HER2+ BC, and we discuss ongoing clinical trials that are investigating these combination approaches.

Intestinal delivery in a long-chain fatty acid formulation enables lymphatic transport and systemic exposure of orlistat

Orlistat is a pancreatic lipase (PL) inhibitor that inhibits dietary lipid absorption and is used to treat obesity. The oral bioavailability of orlistat is considered zero after administration in standard formulations. This is advantageous in the treatment of obesity. However, if orlistat absorption could be improved it has the potential to treat diseases such as acute and critical illnesses where PL transport to the systemic circulation via gut lymph promotes organ failure. Orlistat is highly lipophilic and may associate with intestinal lipid absorption pathways into lymph. Here we investigate the potential to improve orlistat lymph and systemic uptake through intestinal administration in lipid formulations (LFs). The effect of lipid type, lipid dose, orlistat dose, and infusion time on lymph and systemic availability of orlistat was investigated. After administration in all LFs, orlistat concentrations in lymph were greater than in plasma, suggesting direct transport via lymph. Lymph and plasma orlistat derivative concentrations were ~8-fold greater after administration in a long-chain fatty acid (LC-FA) compared to a lipid-free, LC triglyceride (LC-TG) or medium-chain FA (MC-FA) formulation. Overall, administration of orlistat in a LC-FA formulation promotes lymph and systemic uptake which may enable treatment of diseases associated with elevated systemic PL activity.

Lipid metabolic reprogramming as an emerging mechanism of resistance to kinase inhibitors in breast cancer

Breast cancer is one of the leading causes of death in women in the United States. In general, patients with breast cancer undergo surgical resection of the tumor and/or receive drug treatment to kill or suppress the growth of cancer cells. In this regard, small molecule kinase inhibitors serve as an important class of drugs used in clinical and research settings. However, the development of resistance to these compounds, in particular HER2 and CDK4/6 inhibitors, often limits durable clinical responses to therapy. Emerging evidence indicates that PI3K/AKT/mTOR pathway hyperactivation is one of the most prominent mechanisms of resistance to many small molecule inhibitors as it bypasses upstream growth factor receptor inhibition. Importantly, the PI3K/AKT/mTOR pathway also plays a pertinent role in regulating various aspects of cancer metabolism. Recent studies from our lab and others have demonstrated that altered lipid metabolism mediates the development of acquired drug resistance to HER2-targeted therapies in breast cancer, raising an interesting link between reprogrammed kinase signaling and lipid metabolism. It appears that, upon development of resistance to HER2 inhibitors, breast cancer cells rewire lipid metabolism to somehow circumvent the inhibition of kinase signaling. Here, we review various mechanisms of resistance observed for kinase inhibitors and discuss lipid metabolism as a potential therapeutic target to overcome acquired drug resistance.

Evaluation of the antiviral activity of orlistat (tetrahydrolipstatin) against dengue virus, Japanese encephalitis virus, Zika virus and chikungunya virus

Many mosquito transmitted viruses of the genera Alphavirus and Flavivirus are human pathogens of significant concern, and there is currently no specific antiviral for any member of these two genera. This study sought to investigate the broad utility of orlistat (tetrahydrolipstatin) in reducing virus infection for several mosquito borne viruses including flaviviruses (dengue virus (DENV; nine isolates analyzed), Japanese encephalitis virus (JEV; one isolate analyzed) and Zika virus (ZIKV; 2 isolates analyzed)) as well as an alphavirus (chikungunya virus; CHIKV; 2 isolates analyzed). Three different treatment regimens were evaluated, namely pre-treatment (only), post-treatment (only) and pre- and post-treatment, and three factors were evaluated, namely level of infection, virus titer and genome copy number. Results showed that all three treatment modalities were able to significantly reduce virus titer for all viruses investigated, with the exception of three isolates of DENV in the pre-treatment only regimen. Pre- and post-treatment was more effective in reducing the level of infection and genome copy number of all viruses investigated than either pre-treatment or post-treatment alone. Collectively, these results suggest orlistat has potential as a broad-spectrum agent against multiple mosquito transmitted viruses.

Fatty acid synthase inhibitor orlistat impairs cell growth and down-regulates PD-L1 expression of a human T-cell leukemia line

Fatty Acid Synthase (FASN) is responsible for the de novo synthesis of fatty acids, which are involved in the preservation of biological membrane structure, energy storage and assembly of factors involved in signal transduction. FASN plays a critical role in supporting tumor cell growth, thus representing a potential target for anti-cancer therapies. Moreover, this enzyme has been recently associated with increased PD-L1 expression, suggesting a role for fatty acids in the impairment of the immune response in the tumor microenvironment. Orlistat, a tetrahydrolipstatin used for the treatment of obesity, has been reported to reduce FASN activity, while inducing a sensible reduction of the growth potential in different cancer models. We have analyzed the effect of orlistat on different features involved in the tumor cell biology of the T-ALL Jurkat cell line. In particular, we have observed that orlistat inhibits Jurkat cell growth and induces a perturbation of cell cycle along with a decline of FASN activity and protein levels. Moreover, the drug produces a remarkable impairment of PD-L1 expression. These findings suggest that orlistat interferes with different mechanisms involved in the control of tumor cell growth and can potentially contribute to decrease the tumor-associated immune-pathogenesis.

Pharmacologic and Pharmacodynamic Equivalence of 2 Formulations of Orlistat

We sought to establish the bioequivalence of 2 weight-loss aids: orlistat 27-mg chewable tablet and orlistat 60-mg capsule, measured pharmacodynamically as percentage fecal fat excretion. Two open-label, single-center, randomized, 3-period, 3-treatment crossover studies were conducted in adults with body mass index 25-33 kg/m² . For each 9-day treatment period, subjects received orlistat 27-mg chewable tablet, 60-mg capsule, or 120-mg capsules (2 60-mg capsules) 3 times daily; a 2-day washout separated treatments. Primary bioequivalence analyses were based on 2 1-sided tests of the 90% CI of the ratio of geometric means using log-transformed data (study 1) and by the dose-scale method to calculate bias-corrected and accelerated 90% CI of relative bioavailability (f) using nontransformed data (study 2). Bioequivalence was established if 90% CIs fell within 0.80-1.25. In total, 48 and 144 subjects were randomized in study 1 and study 2, respectively. Bioequivalence between the formulations was established in both studies: study 1 ratio of geometric means of percentage fecal fat excretion was 0.96 (2 1-sided tests, 90% CI 0.87-1.06); study 2-point estimate of f was 1.09 (bias-corrected and accelerated 90% CI 0.98-1.22). Tolerability of the 27-mg tablet was consistent with the 60-mg capsule; mild gastrointestinal effects were most common.

Fatty acid synthase (FASN) as a therapeutic target in breast cancer

INTRODUCTION

Ten years ago, we put forward the metabolo-oncogenic nature of fatty acid synthase (FASN) in breast cancer. Since the conception of this hypothesis, which provided a model to explain how FASN is intertwined with various signaling networks to cell-autonomously regulate breast cancer initiation and progression, FASN has received considerable attention as a therapeutic target. However, despite the ever-growing evidence demonstrating the involvement of FASN as part of the cancer-associated metabolic reprogramming, translation of the basic science-discovery aspects of FASN blockade to the clinical arena remains a challenge. Areas covered: Ten years later, we herein review the preclinical lessons learned from the pharmaceutical liabilities of the first generation of FASN inhibitors. We provide an updated view of the current development and clinical testing of next generation FASN-targeted drugs. We also discuss new clinico-molecular approaches that should help us to convert roadblocks into roadways that will propel forward our therapeutic understanding of FASN. Expert opinion: With the recent demonstration of target engagement and early signs of clinical activity with the first orally available, selective, potent and reversible FASN inhibitor, we can expect Big pharma to revitalize their interest in lipogenic enzymes as well-credentialed targets for oncology drug development in breast cancer.

Orlistat

Each month, subscribers to The Formulary® Monograph Service receive five to six researched monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board called The Formulary Information Exchange (The F.I.X). All topics pertinent to clinical pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The October 1999 Formulary monographs are on zanamivir, pioglitazone, levobupivacaine, temozolomide, and insulin glargine. The DUE is on zanamivir.

Involvement of fatty acid synthase in dengue virus infection

Background

The mosquito transmitted Dengue virus (DENV) remains a significant public health problem in many tropical and subtropical countries. Increasing evidence has suggested that during the infection process cellular lipids play important roles at several stages of the replication cycle. This study sought to characterize the changes in lipid metabolism gene expression and investigated the role of one enzyme, fatty acid synthase, in DENV infection.

Methods

Transcriptional profiles of genes associated with lipid metabolism were evaluated by real-time PCR after infection of different cell lines (HepG2 and HEK293T/17) and with different DENVs (laboratory adapted and low passage). Expression profiles of genes were evaluated by western blotting. A critical lipid metabolism protein, fatty acid synthase was down-regulated through siRNA and inhibited with orlistat and the effect on DENV infection determined by flow cytometry, plaque assay, western blotting and confocal microscopy.

Results

The results showed alterations of gene transcription and expression were seen in genes variously associated with lipogenesis, lipolysis and fatty acid β-oxidation during DENV infection. Interference of fatty acid synthase with either siRNA or orlistat had marked effects on virus production, with orlistat having an EC₅₀ value of 10.07 μM at 24 h post infection. However, non-structural protein expression was largely unaffected.

Conclusions

While drug treatment reduced virus titer by up to 3Log10, no significant effect on DENV non-structural protein expression was observed, suggesting that fatty acid synthase acts through an effect on virion formation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-017-0685-9) contains supplementary material, which is available to authorized users.

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.

Development of a Self-Assembled Nanoparticle Formulation of Orlistat, Nano-ORL, with Increased Cytotoxicity against Human Tumor Cell Lines

Fatty acid synthase (FASN), the enzyme that catalyzes de novo synthesis of fatty acids, is expressed in many cancer types. Its potential as a therapeutic target is well recognized, but inhibitors of FASN have not yet been approved for cancer therapy. Orlistat (ORL), an FDA-approved lipase inhibitor, is also an effective inhibitor of FASN. However, ORL is extremely hydrophobic and has low systemic uptake after oral administration. Thus, new strategies are required to formulate ORL for cancer treatment as a FASN inhibitor. Here, we report the development of a nanoparticle (NP) formulation of ORL using amphiphilic bioconjugates that are derived from hyaluronic acid (HA), termed Nano-ORL. The NPs were loaded with up to 20 wt % weight of ORL at greater than 95% efficiency. The direct inhibition of the human recombinant thioesterase domain of FASN by ORL extracted from Nano-ORL was similar to that of stock ORL. Nano-ORL demonstrated a similar ability to inhibit cellular FASN activity when compared to free ORL, as demonstrated by analysis of (14)C-acetate incorporation into lipids. Nano-ORL treatment also disrupted mitochondrial function similarly to ORL by reducing adenosine triphosphate turnover in MDA-MB-231 and LNCaP cells. Nano-ORL demonstrated increased potency compared to ORL toward prostate and breast cancer cells. Nano-ORL decreased viability of human prostate and breast cancer cell lines to 55 and 57%, respectively, while free ORL decreased viability to 71 and 79% in the same cell lines. Moreover, Nano-ORL retained cytotoxic activity after a 24 h preincubation in aqueous conditions. Preincubation of ORL dramatically reduced the efficacy of ORL as indicated by high cell viability (>85%) in both breast and prostate cell lines. These data demonstrate that NP formulation of ORL using HA-derived polymers retains similar levels of FASN, lipid synthesis, and ATP turnover inhibition while significantly improving the cytotoxic activity against cancer cell lines.

Orlistat limits cholesterol intestinal absorption by Niemann-pick C1-like 1 (NPC1L1) inhibition

The known mechanism by which orlistat decreases the absorption of dietary cholesterol is by inhibition of intestinal lipases. The aim of this study was to investigate the ability of orlistat to limit cholesterol absorption by inhibition of the cholesterol transport protein Niemann-Pick C1-like 1 (NPC1L1) as another mechanism of action. In situ rat intestinal perfusion studies were conducted to study the effect of orlistat on jejunal cholesterol absorption. Inhibition kinetic parameters were calculated from in vitro inhibition studies using Caco2 and NPC1L1 transfected cell lines. The in situ studies demonstrated that intestinal perfusion of orlistat (100µM) was able to reduce cholesterol absorption by three-fold when compared to control (i.e. in the absence of orlistat, P<0.01). In vitro studies using Caco2 cells demonstrated orlistat to reduce the cellular uptake of cholesterol by 30%. Additionally, orlistat reduced the cellular uptake of cholesterol in dose dependent manner in NPC1L1 transfected cell line with an IC50=1.2µM. Lineweaver-Burk plot indicated a noncompetitive inhibition of NPC1L1 by orlistat. Beside the already established mechanism by which orlistat reduces the absorption of cholesterol, we demonstrated for the first time that orlistat limits cholesterol absorption by the inhibition of NPC1L1 transport protein.

Fatty acid synthase overexpression: target for therapy and reversal of chemoresistance in ovarian cancer

Background

Fatty acid synthase (FASN) is crucial to de novo long-chain fatty acid synthesis, needed to meet cancer cells’ increased demands for membrane, energy, and protein production.

Methods

We investigated FASN overexpression as a therapeutic and chemosensitization target in ovarian cancer tissue, cell lines, and primary cell cultures. FASN expression at mRNA and protein levels was determined by quantitative real-time polymerase chain reaction and immunoblotting and immunohistochemistry, respectively. FASN inhibition’s impact on cell viability, apoptosis, and fatty acid metabolism was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide assay, cell death detection enzyme-linked immunosorbent assay, immunoblotting, and ¹⁸ F-fluoromethylcholine uptake measurement, respectively.

Results

Relative to that in healthy fallopian tube tissue, tumor tissues had 1.8-fold average FASN protein overexpression; cell lines and primary cultures had 11-fold–100-fold mRNA and protein overexpression. In most samples, the FASN inhibitor cerulenin markedly decreased FASN expression and cell viability and induced apoptosis. Unlike concomitant administration, sequential cerulenin/cisplatin treatment reduced cisplatin’s half maximal inhibitory concentration profoundly (up to 54%) in a cisplatin-resistant cell line, suggesting platinum (re)sensitization. Cisplatin-resistant cells displayed lower ¹⁸ F-fluoro-methylcholine uptake than did cisplatin-sensitive cells, suggesting that metabolic imaging might help guide therapy.

Conclusions

FASN inhibition induced apoptosis in chemosensitive and platinum-resistant ovarian cancer cells and may reverse cisplatin resistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0511-3) contains supplementary material, which is available to authorized users.

Benefit-risk assessment of orlistat in the treatment of obesity

Orlistat, an inhibitor of intestinal lipase, has been available for the treatment of obesity for nearly two decades. In conjunction with a hypocaloric diet, orlistat treatment results in a placebo-subtracted reduction in body weight of around 3 kg at 1 year, and increases the likelihood of achieving clinically significant (≥5%) weight loss by around 20%. Orlistat-induced weight loss also confers modest improvements in systolic and diastolic blood pressure, low-density lipoprotein (LDL) cholesterol, glycemic parameters, and progression to diabetes in people with impaired glucose tolerance. Overall, it has a good safety profile, and serious adverse events (including reports of severe kidney and liver injury) are rare. However, a high rate of gastrointestinal side effects limits adherence to treatment.

Fate and uptake of pharmaceuticals in soil-earthworm systems

Pharmaceuticals present a potential threat to soil organisms, yet our understanding of their fate and uptake in soil systems is limited. This study therefore investigated the fate and uptake of (14)C-labeled carbamazepine, diclofenac, fluoxetine, and orlistat in soil-earthworm systems. Sorption coefficients increased in the order of carbamazepine < diclofenac < fluoxetine < orlistat. Dissipation of (14)C varied by compound, and for orlistat, there was evidence of formation of nonextractable residues. Uptake of (14)C was seen for all compounds. Depuration studies showed complete elimination of (14)C for carbamazepine and fluoxetine treatments and partial elimination for orlistat and diclofenac, with greater than 30% of the (14)C remaining in the tissue at the end of the experiment. Pore-water-based bioconcentration factors (BCFs), based on uptake and elimination of (14)C, increased in the order carbamazepine < diclofenac < fluoxetine and orlistat. Liquid chromatography-tandem mass spectrometry and liquid chromatography-Fourier transform mass spectrometry indicated that the observed uptake in the fluoxetine and carbamazepine treatments was due to the parent compounds but that diclofenac was degraded in the test system so uptake was due to unidentifiable transformation products. Comparison of our data with outputs of quantitative structure-activity relationships for estimating BCFs in worms showed that these models tend to overestimate pharmaceutical BCFs so new models are needed.

Carboxylesterase-2 is a highly sensitive target of the antiobesity agent orlistat with profound implications in the activation of anticancer prodrugs

Orlistat has been the most used anti-obesity drug and the mechanism of its action is to reduce lipid absorption by inhibiting gastrointestinal lipases. These enzymes, like carboxylesterases (CESs), structurally belong to the α/β hydrolase fold superfamily. Lipases and CESs are functionally related as well. Some CESs (e.g., human CES1) have been shown to hydrolyze lipids. This study was designed to test the hypothesis that orlistat inhibits CESs with higher potency toward CES1 than CES2, a carboxylesterase with little lipase activity. Liver microsomes and recombinant CESs were tested for the inhibition of the hydrolysis of standard substrates and the anticancer prodrugs pentyl carbamate of p-aminobenzyl carbamate of doxazolidine (PPD) and irinotecan. Contrary to the hypothesis, orlistat at 1 nM inhibited CES2 activity by 75% but no inhibition on CES1, placing CES2 one of the most sensitive targets of orlistat. The inhibition varied among some CES2 polymorphic variants. Pretreatment with orlistat reduced the cell killing activity of PPD. Certain mouse but not rat CESs were also highly sensitive. CES2 is responsible for the hydrolysis of many common drugs and abundantly expressed in the gastrointestinal track and liver. Inhibition of this carboxylesterase probably presents a major source for altered therapeutic activity of these medicines if co-administered with orlistat. In addition, orlistat has been linked to various types of organ toxicities, and this study provides an alternative target potentially involved in these toxicological responses.

Overexpression of FAS and Ki-67 in aberrant crypt foci from patients with adenoma

AIM: To detect the expression of fatty acid synthase (FAS) and Ki-67 in colonic adenoma and aberrant crypt foci to explore their significance in the formation of precancerous lesions.

METHODS: Aberrant crypt foci (ACF) in the rectum of 34 patients with adenoma were identified by magnification chromoendoscopy (MCE) after staining with 0.2% methylene blue solution. Specimens with ACF were biopsied to detect the expression of FAS and Ki-67 by immunohistochemistry.

RESULTS: A total of 166 ACF were found in 31 patients, of which 14 had atypical hyperplasia and 152 had no atypical hyperplasia. The expression of FAS and Ki-67 in colonic adenoma and ACF were significantly higher than that in normal tissue (all P < 0.01). There was no significant difference in the expression of FAS and Ki-67 between ACF with and without dysplasia.

CONCLUSION: The expression of FAS and Ki-67 is higher in colorectal precancerous lesions. FAS may be used as a target for preventing and treating colorectal cancer.

Weight loss is still an essential intervention in obesity and its complications: a review

The prevalence of obesity is more than 20% in many developed countries and it increases in developing countries. Obesity is associated with metabolic disorders, cardiovascular diseases, pulmonary diseases, digestive diseases, and cancers. Although other specific treatments for these complications exist, weight loss is still an essential intervention in obesity and its complications. Therapeutic life change, behavior modification, pharmacotherapy, and surgery are major approaches to weight loss. In addition, medicine used in diabetes such as Glucagon-like peptide-1 analogues may be a new type of medicine for obesity, at least for those obese patients with diabetes.

Antiobesity and lipid lowering effects of Glycyrrhiza chalcones: experimental and computational studies

Twelve flavonoids (1-12), isolated from Glycyrrhiza glabra roots were evaluated for their pancreatic lipase (PL) inhibitory activity in vitro. The structures of the isolated compounds were elucidated by spectroscopic methods. Amongst all the compounds 7, 8, 10 and 11 showed strong inhibition against PL with IC(50) values of 7.3 μM, 35.5 μM, 14.9 μM and 37.6 μM, respectively. Molecular docking studies on the most active compound 7 revealed that it binds with the key amino acid residues of the PL active site. In silico absorption, distribution, metabolism and excretion (ADME) parameters were also computed on the active compounds to determine their preliminary pharmacokinetic properties. Further, investigations were carried out to determine the antiobesity and lipid lowering effects of 7 and 10 in high fat diet (HFD) fed male SD rats. In the rats supplemented with compound 7 the body weight increase was only 23.2±3.6 g as compared to 64.2±0.5 g in the HFD control group while in the rats treated with compound 10 showed 23.2±3.6 g weight gain only. Compound 7 decreased the levels of plasma total cholesterol (TC) to 84.6±1.4 mg/dl and plasma total triglycerides (TG) to 128.8±6.0 mg/dl. Compound 10 also lowered the plasma TC and TG levels considerably. The results indicate the potential of the chalcone scaffold as a source of PL inhibitors for preventing obesity.

Medical and surgical treatment of obesity

The prevalence of obesity has reached epidemic proportions. Conceptualization of obesity as a chronic disease facilitates greater understanding its treatment. The NIH Consensus Conference on Gastrointestinal Surgery for Severe Obesity provides a framework by which to manage the severely obese--specifically providing medical versus surgical recommendations which are based on scientific and outcomes data. Medical treatments of obesity include primary prevention, dietary intervention, increased physical activity, behavior modification, and pharmacotherapy. Surgical treatment for obesity is based on the extensive neural-hormonal effects of weight loss surgery on metabolism, and as such is better termed Metabolic Surgery. Surgery is not limited to the procedure itself, it also necessitates thorough preoperative evaluation, risk assessment, and counseling. The most common metabolic surgical procedures include Roux-en-Y gastric bypass, adjustable gastric band, sleeve gastrectomy, and biliopancreatic diversion. Surgical outcomes for metabolic surgery are well studied and demonstrate superior long-term weight loss compared to medical management in cases of severe obesity.

Metabolic alterations and targeted therapies in prostate cancer

Cancer cells synthesize de novo large amounts of fatty acids and cholesterol, irrespective of the circulating lipid levels and benefit from this increased lipid synthesis in terms of growth advantage, self-survival and drug resistance. Key lipogenic alterations that commonly occur in prostate cancer include over-expression of the enzyme fatty acid synthase (FASN) and deregulation of the 5-AMP-activated protein kinase (AMPK). FASN is a key metabolic enzyme that catalyses the synthesis of palmitate from the condensation of malonyl-CoA and acetyl-CoA de novo and plays a central role in energy homeostasis, by converting excess carbon intake into fatty acids for storage. AMPK functions as a central metabolic switch that governs glucose and lipid metabolism. Recent interest has focused on the potential of targeting metabolic pathways that may be altered during prostate tumorigenesis and progression. Several small molecule inhibitors of FASN have now been described or in development for therapeutic use; in addition, drugs that directly or indirectly induce AMPK activation have potential benefit in prostate cancer prevention and treatment.

Fatty acid synthase as a potential therapeutic target in cancer

Fatty acid synthase (FASN) is a key enzyme involved in neoplastic lipogenesis. Overexpression of FASN is common in many cancers, and accumulating evidence suggests that it is a metabolic oncogene with an important role in tumor growth and survival, making it an attractive target for cancer therapy. Early small-molecule FASN inhibitors such as cerulenin, C75 and orlistat have been shown to induce apoptosis in several cancer cell lines and to induce tumor growth delay in several cancer xenograft models but their mechanism is still not well understood. These molecules suffer from pharmacological limitations and weight loss as a side effect that prevent their development as systemic drugs. Several potent inhibitors have recently been reported that may help to unravel and exploit the full potential of FASN as a target for cancer therapy in the near future. Furthermore, novel sources of FASN inhibitors, such as green tea and dietary soy, make both dietary manipulation and chemoprevention potential alternative modes of therapy in the future.

Efficacy and tolerability of the association of sibutramine and orlistat for six months in overweight and obese patients

Objective. To assess the efficacy and tolerability of the association sibutramine (10-20 mg/day) and orlistat (120 mg 2-3 times a day) in the treatment of obesity in a six-month open trial. Methods. 446 overweight and obese patients who sought treatment for obesity in a private clinic were assessed every 2 weeks during a period of 3 and 6 months. Results. After 3 months, the mean weight loss was 10.5 kg (-9.8% of the initial weight, n = 263), and after 6 months, the mean weight loss was 13.9 kg (-12.8% of the initial weight, n = 97). The tolerability of such association was quite acceptable and coherent with the action mechanism of each component. Conclusions. The association of orlistat and sibutramine is quite efficient and it seems to promote a higher rate of weight loss than that reported in clinical studies performed with each drug separately.

What is the Objective of the Mass Balance Study? A Retrospective Analysis of Data in Animal and Human Excretion Studies Employing Radiolabeled Drugs

Mass balance excretion studies in laboratory animals and humans using radiolabeled compounds represent a standard part of the development process for new drugs. From these studies, the total fate of drug-related material is obtained: mass balance, routes of excretion, and, with additional analyses, metabolic pathways. However, rarely does the mass balance in radiolabeled excretion studies truly achieve 100% recovery. Many definitions of cutoff criteria for mass balance that identify acceptable versus unacceptable recovery have been presented as ad hoc statements without a strong rationale. To address this, a retrospective analysis was undertaken to explore the overall performance of mass balance studies in both laboratory animal species and humans using data for 27 proprietary compounds within Pfizer and extensive review of published studies. The review has examined variation in recovery and the question of whether low recovery was a cause for concern in terms of drug safety. Overall, mean recovery was greater in rats and dogs than in humans. When the circulating half-life of total radioactivity is greater than 50 h, the recovery tends to be lower. Excretion data from the literature were queried as to whether drugs linked with toxicities associated with sequestration in tissues or covalent binding exhibit low mass balance. This was not the case, unless the sequestration led to a long elimination half-life of drug-related material. In the vast majority of cases, sequestration or concentration of drug-related material in an organ or tissue was without deleterious effect and, in some cases, was related to the pharmacological mechanism of action. Overall, from these data, recovery of radiolabel would normally be equal to or greater than 90%, 85%, and 80% in rat, dog, and human, respectively. Since several technical limitations can underlie a lack of mass balance and since mass balance data are not sensitive indicators of the potential for toxicity arising via tissue sequestration, absolute recovery in humans should not be used as a major decision criteria as to whether a radiolabeled study has met its objectives. Instead, the study should be seen as an integral part of drug development answering four principal questions: 1) Is the proposed clearance mechanism sufficiently supported by the identities of the drug-related materials in excreta, so as to provide a complete understanding of clearance and potential contributors to interpatient variability and drug-drug interactions? 2) What are the drug-related entities present in circulation that are the active principals contributing to primary and secondary pharmacology? 3) Are there findings (low extraction recovery of radiolabel from plasma, metabolite structures indicative of chemically reactive intermediates) that suggest potential safety issues requiring further risk assessment? 4) Do questions 2 and 3 have appropriate preclinical support in terms of pharmacology, safety pharmacology, and toxicology? Only if one or more of these four questions remain unanswered should additional mass balance studies be considered.

Orlistat-associated adverse effects and drug interactions: a critical review

Orlistat, an anti-obesity drug, is a potent and specific inhibitor of intestinal lipases. In light of the recent US FDA approval of the over-the-counter sale of orlistat (60 mg three times daily), clinicians need to be aware that its use may be associated with less well known, but sometimes clinically relevant, adverse effects. More specifically, the use of orlistat has been associated with several mild-to-moderate gastrointestinal adverse effects, such as oily stools, diarrhoea, abdominal pain and faecal spotting. A few cases of serious hepatic adverse effects (cholelithiasis, cholostatic hepatitis and subacute liver failure) have been reported. However, the effects of orlistat on non-alcoholic fatty liver disease are beneficial. Orlistat-induced weight loss seems to have beneficial effects on blood pressure. No effect has been observed on calcium, phosphorus, magnesium, iron, copper or zinc balance or on bone biomarkers. Interestingly, the use of orlistat has been associated with rare cases of acute kidney injury, possibly due to the increased fat malabsorption resulting from the inhibition of pancreatic and gastric lipase by orlistat, leading to the formation of soaps with calcium and resulting in increased free oxalate absorption and enteric hyperoxaluria. Orlistat has a beneficial effect on carbohydrate metabolism. No significant effect on cancer risk has been reported with orlistat.Orlistat interferes with the absorption of many drugs (such as warfarin, amiodarone, ciclosporin and thyroxine as well as fat-soluble vitamins), affecting their bioavailability and effectiveness. This review considers orlistat-related adverse effects and drug interactions. The clinical relevance and pathogenesis of these effects is also discussed.

Orlistat for the management of overweight individuals and obesity: a review of potential for the 60-mg, over-the-counter dosage

Orlistat, in the 60-mg over-the-counter dose, was recently approved by the FDA. This lipase inhibitor blocks absorption of ~25% of ingested fat and has ~85% of the efficacy of the 120-mg dose for weight loss. Over 16 weeks weight loss with diet and orlistat 60 mg averages ~5% of initial body weight. The 60-mg dose is better tolerated than the 120-mg dose and the gastrointestinal side effects are minimal when individuals consume < 30% of their energy from fat. In addition to facilitating modest weight loss, orlistat use decreases serum LDL-cholesterol values by ~10%. When taken three times daily before meals, orlistat 60 mg modifies lifestyle behavior, encourages lower fat-consumption and sets the stage for other healthy lifestyle changes.

Long-term pharmacotherapy for obesity

Obese patients unable to achieve significant weight loss with lifestyle changes alone may require drug therapy, and such therapy may be needed long term lest weight lost be regained. In the United States, only sibutramine and orlistat are available for the long-term treatment of obesity. Clinical trials have shown that both drugs can induce and maintain weight loss, even in patients with comorbid conditions such as hypertension or type 2 diabetes. Their use must be combined with behavior modification and a structured meal plan, however, for patients to reap the full benefits of such treatment.

Orlistat: a review of its use in the management of patients with obesity

Orlistat is an inhibitor of gastrointestinal lipases and, therefore, prevents the absorption of dietary fat. This agent reduces weight in obese adults and adolescents with or without comorbidities (including type 2 diabetes mellitus, hypercholesterolaemia, hypertension, metabolic syndrome) who received up to 4 years of therapy in conjunction with a hypocaloric diet. In obese patients, orlistat in combination with a hypocaloric diet improved metabolic risk factors and reduced the risk of developing type 2 diabetes. Furthermore, this agent was cost effective in patients with obesity, particularly those with type 2 diabetes. Orlistat is generally well tolerated, with gastrointestinal adverse events being most commonly reported. Orlistat, in addition to lifestyle and dietary intervention, is thus an attractive option for the treatment of patients with obesity, especially those with associated comorbidities or at risk of developing type 2 diabetes.

Spotlight on Orlistat in the Management of Patients with Obesity1

Orlistat is an inhibitor of gastrointestinal lipases and, therefore, prevents the absorption of dietary fat. This agent reduced weight in obese adults and adolescents with or without co-morbidities (including type 2 diabetes mellitus, hypercholesterolemia, hypertension, metabolic syndrome) who received up to 4 years of therapy in conjunction with a hypocaloric diet. In obese patients, orlistat in combination with a hypocaloric diet improved metabolic risk factors and reduced the risk of developing type 2 diabetes. Furthermore, this agent was cost effective in patients with obesity, particularly those with type 2 diabetes. Orlistat is generally well tolerated, with gastrointestinal adverse events being most commonly reported. Orlistat, in addition to lifestyle and dietary intervention, is thus an attractive option for the treatment of patients with obesity, especially those with associated co-morbidities or at risk of developing type 2 diabetes.

Clinical Implications of Obesity With Specific Focus on Cardiovascular Disease

Obesity adversely affects cardiac function, increases the risk factors for coronary heart disease, and is an independent risk factor for cardiovascular disease. The risk of developing coronary heart disease is directly related to the concomitant burden of obesity-related risk factors. Modest weight loss can improve diastolic function and affect the entire cluster of coronary heart disease risk factors simultaneously. This statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism reviews the relationship between obesity and the cardiovascular system, evaluates the effect of weight loss on coronary heart disease risk factors and coronary heart disease, and provides practical weight management treatment guidelines for cardiovascular healthcare professionals. The data demonstrate that weight loss and physical activity can prevent and treat obesity-related coronary heart disease risk factors and should be considered a primary therapy for obese patients with cardiovascular disease.

Orlistat in the treatment of obesity

Orlistat has been well studied in several populations, including patients who do and do not have type 2 diabetes and in patients who have impaired glucose tolerance. Overall, modest, but significant, weight loss was seen in all three groups of patients with favorable effects on the comorbidities of obesity. Orlistat has not been associated with a serious adverse event profile, and the mild GI effects that are seen in some patients are well tolerated. In obese patients who do not have diabetes, weight loss is achieved and maintained as shown in the 2-year studies. Moreover, as was well documented in the Swedish multi-morbidity study, favorable treatment effects on the constituents of the metabolic syndrome are seen. Orlistat, together with a hypocaloric diet, was proven to be effective in preventing diabetes in patients who had impaired glucose tolerance. The addition of orlistat resulted in significant weight loss and significance decreases in levels of HbA1c in patients who had type 2 diabetes who were treated with antihyperglycemic drugs. Studies showed that it is possible to identify early which patients may respond best to treatment. Orlistat offers an attractive treatment option for obese patients who do and do not have diabetes and as a combination drug for treatment of obese patients who have type 2 diabetes.

Changes in abdominal subcutaneous fat water content with rapid weight loss and long-term weight maintenance in abdominally obese men and women

OBJECTIVE

Insulin resistance decreases blood flow and volume in fat tissue. We hypothesised that fat tissue nutritive blood flow and volume, and thereby water content, would increase during weight loss and weight maintenance in obese persons.

DESIGN

Longitudinal clinical intervention with a 9-week very-low-calorie diet (VLCD) followed by one year of weight maintenance.

SUBJECTS

Obese men (n=13) and women (n=14) with the metabolic syndrome.

MEASUREMENTS

Water content of abdominal subcutaneous fat tissue as estimated by a sensor on the skin surface measuring the dielectric constant at 300 MHz. Anthropometric measures of fatness and fat distribution. Biochemical measures related to insulin resistance.

RESULTS

Subjects lost 14.5+/-3.4% of body weight during the VLCD, and generally sustained this weight loss during weight maintenance. Insulin sensitivity as estimated by an index (qualitative insulin sensitivity check index) increased during the VLCD, and remained increased throughout weight maintenance. The dielectric constant increased from 23.3+/-2.3 to 25.0+/-2.1 (P<0.001) during the VLCD, and further to 27.8+/-1.9 (P<0.001) during weight maintenance, indicating an increase in the water content of subcutaneous fat. The increase in subcutaneous fat water content did not correlate with weight loss and other measures of adiposity during the VLCD, but there was an inverse correlation that strengthened in significance from baseline to 6, 9 and 12 mo (r=-0.32 to -0.64, P=0.079-0.002). Increases in subcutaneous fat water content also correlated with improvements in insulin sensitivity at 6, 9 and 12 months of weight maintenance (r=0.34-0.54, P=0.094-0.006).

CONCLUSIONS

Water content of abdominal subcutaneous adipose tissue increases with weight loss in obese persons with the metabolic syndrome, and may reflect increased subcutaneous fat tissue nutritive blood flow. The increase in water content correlates with the increase in insulin sensitivity, suggesting that weight loss and consequent improved insulin sensitivity could mediate the increase in abdominal subcutaneous fat hydration.

Latin-American trial of orlistat for weight loss and improvement in glycaemic profile in obese diabetic patients

AIM

To determine if obese non-insulin-dependent diabetic patients lose more weight when treated for 24 weeks (6 months) with orlistat (120 mg t.i.d.), in conjunction with a hypocaloric diet plus behavioural counselling, than when treated by placebo (t.i.d.) plus similar instructions. The secondary objectives were to evaluate the effects on glucose profile and to determine the tolerability and safety of orlistat.

DESIGN

Double-blind, parallel, randomized, placebo-controlled, multicentre study.

SUBJECTS

Obese, non-insulin-dependent diabetic patients, aged 18-70 years old, with BMI > 27 kg/m2, evaluated at 10 Latin-American centres, in five countries. EFFICACY AND TOLERABILITY MEASUREMENTS: After screened, eligible patients passed by a 2-week placebo run-in period receiving a hypocaloric diet. On day 0, patients were randomized to orlistat or placebo for 24 weeks. At each visit, body weight, blood pressure and waist circumference were measured. At the screening visit, baseline visit (week 0), and at weeks 8, 16 and 24, a central laboratory was in charge of measuring fasting glucose and insulin, HbA1c, postprandial glucose and insulin, fasting total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and postprandial triglycerides. Other safety laboratory assessments were measured locally at the screening visit, baseline visit and at the end of the study. Adverse events were assessed at each visit from baseline.

RESULTS

After 24 weeks of treatment, the orlistat group lost an average of 4.7% of initial body weight vs. 3.0% in the placebo group (p = 0.0003). A greater weight loss was achieved in the orlistat compared with the placebo group (4.24 +/- 0.23 vs. 2.58 +/- 1.46 kg, p = 0.0003). Almost twice as many patients receiving orlistat (30% vs. 17%) lost > or = 5% of initial body weight (p = 0.003). Orlistat treatment plus diet compared to placebo plus diet was associated with significant improvement in glycaemic control, as reflected in decreases in HbA1c (p = 0.04), fasting plasma glucose (p = 0.036) and postprandial glucose (p = 0.05). Orlistat-treated patients had a mean decrease in glucose levels of 1.00 +/- 0.34 mmol/l [3.7%] vs. 0.01 +/- 0.30 mmol/l for placebo group, at week 24 and an absolute decrease of HbA1c of 0.61 +/- 0.15 vs. a decrease of 0.22 +/- 0.14% in the placebo group. Orlistat therapy also resulted in significantly greater improvements than placebo in lipid profile, with reductions in total cholesterol (p = 0.0001) and LDL-cholesterol (p = 0.002). Mild to moderate transient gastrointestinal events were reported, mainly with orlistat treatment, but their association with withdrawal from the study was low.

CONCLUSION

Orlistat is a useful and an effective therapy in obese diabetic patients, promoting clinically significant weight loss and improved glycaemic control and lipid profile.

Weight loss and weight maintenance, ambulatory blood pressure and cardiac autonomic tone in obese persons with the metabolic syndrome

BACKGROUND

Cardiac autonomic function may play a role in obesity-associated hypertension. Most studies on the effects of weight loss on blood pressure and autonomic function do not distinguish between acute or continuing weight loss and steady-state weight maintenance after weight loss.

OBJECTIVES

We sought to clarify the changes in ambulatory blood pressure, heart rate and heart rate variability as assessed by spectral analysis during rapid weight loss and extended weight maintenance.

PARTICIPANTS

Abdominally obese (body mass index 35.2 +/- 2.1 kg/m2, waist 114.3 +/- 9.0 cm) men and women (n = 41) with the metabolic syndrome.

METHODS AND RESULTS

The 34 men and women completing the 1-year weight maintenance period lost 14.6 +/- 3.5 kg during the 9-week very-low-calorie diet and maintained a 12.5 +/- 7.5 kg weight loss to the end of the trial. Ambulatory 24-h blood pressure decreased dramatically during the diet (-9.0 +/- 8.0/-4.6 +/- 4.9 mmHg), but had risen to near baseline levels by the end of weight maintenance (-2.2 +/- 8.2 /-1.2 +/- 6.1 mmHg). Night-time heart rate decreased (-5.5 +/- 9.6 beats/min, P = 0.012), and heart rate variability total and low-frequency power measured during 5 min of controlled breathing increased by 46-56% (P = 0.003-0.09) during rapid weight loss. These changes gradually attenuated during weight maintenance, and only the change in night-time heart rate was still of borderline significance after 1 year of weight maintenance (-3.6 +/- 8.6 beats/min, P = 0.063). Heart rate variability high-frequency power tended to increase during weight loss and weight maintenance.

CONCLUSION

Despite successful weight maintenance, the decrease in ambulatory blood pressure after rapid weight loss was largely transient. The increase in parasympathetic tone was more sustained, but also gradually attenuated during 1 year of weight maintenance.

Weight management and current options in pharmacotherapy: orlistat and sibutramine

BACKGROUND

Chronic obesity is associated with various cardiovascular disorders, including diabetes, dyslipidemia, and hypertension. Pharmacotherapy with antiobesity agents is an important management strategy in conjunction with lifestyle interventions.

OBJECTIVE

This article describes the pharmacologic management of obesity, concentrating on orlistat and sibutramine.

METHODS

Relevant articles were identified through a MEDLINE search (1966-February 2002) using the terms obesity, overweight, weight loss, antiobesity drugs, orlistat, and sibutramine. The search for efficacy trials was limited to randomized controlled studies of >6 months' duration. Also included in the review were relevant references cited in the bibliographies of identified articles, news reports, and the authors' own data.

RESULTS

Orlistat reduces fat absorption by inhibiting gastrointestinal lipases. In randomized, controlled trials of up to 2 years' duration, orlistat plus a hypocaloric diet produced significantly greater weight loss than placebo (P < 0.001). In the maintenance phase, patients taking orlistat had less weight regain than did placebo recipients. The weight reduction with orlistat was also associated with a significant improvement in control of cardiovascular risk factors (P < 0.05). Unlike orlistat, sibutramine works by suppressing appetite; its efficacy, however, was similar to that of orlistat in the identified clinical trials. Orlistat was associated primarily with gastrointestinal side effects. Use of orlistat was associated with minimal drug interactions, except with cyclosporine, with which it should not be taken. Sibutramine was also well tolerated, although it may cause dry mouth, anorexia, and insomnia, and should be used with caution in patients at risk for cardiovascular disease.

CONCLUSIONS

Orlistat and sibutramine demonstrated a favorable efficacy and safety profile in randomized controlled trials. Current evidence supports their use as adjuncts to lifestyle modifications in the treatment of obesity.