Model for Predicting the Effect of Sibutramine Therapy in Obesity.

Background: The development of models predicting response to weight loss therapy using sibutramine is found in only a few cases. The objective of the work is to develop a data-driven method of personalized recommendation for obesity treatment that would predict the response to sibutramine based on the current set of patient parameters. Methods: The decision system is built on the XGBoost classification algorithm along with recursive feature selection and Shapley data valuation. Using the results of clinical trials, it was trained to estimate the probability of overcoming a weight loss threshold. The model was evaluated by the accuracy metric using the Leave-One-Out cross-validation. Results: The model for predicting response to sibutramine treatment over 3 months has an accuracy of 71%. The model for predicting outcomes at the sixth month visit based on results at 3 months has an accuracy of 80%. Conclusions: Although our developed prediction model may not exhibit high precision compared to certain benchmarks, it significantly outperforms random chance or models relying only on BMI parameters. Our model used the available range of laboratory tests, which makes it possible to use this model for routine clinical use and help doctors decide whether to prescribe sibutramine.

Sibutramine-induced pheochromocytoma crisis: A rare and lethal occurrence.

Pheochromocytoma is a neuroendocrine tumor that secretes catecholamines; excessive catecholamine secretion can lead to pheochromocytoma crisis (PCC), a rare and life-threatening condition. Sibutramine, a serotonin and norepinephrine reuptake inhibitor, was previously used for obesity treatment but is now banned due to its cardiovascular side effects. Although fatalities related to PCC and adverse events associated with sibutramine have been frequently reported individually, there is no documented literature addressing PCC-induced by sibutramine. Here we report a rare case of fatal sibutramine-induced PCC in a previously asymptomatic young female with undiagnosed pheochromocytoma. The 25-year-old patient took a weight-loss pill containing sibutramine for the first time and subsequently experienced nausea, vomiting, chest tightness, and other symptoms. She went to hospital about 6 hours after taking the pill but died approximately 4 hours later despite the resuscitation efforts. An autopsy revealed a pheochromocytoma in the right adrenal gland. The cause of death was attributed to sibutramine-induced PCC. To our knowledge, this is the first report to document the occurrence of sibutramine-induced PCC.

Development and validation of a high-performance thin-layer chromatography method for detection of sibutramine in dietary supplements.

INTRODUCTION: In the period between 1997 and 2010, sibutramine-containing drugs were widely prescribed for obesity and over-weight management. Due to safety concerns, in 2010 all medicines containing sibutramine were urgently withdrawn from the USA and European pharmaceutical market. Although sibutramine is no longer available in pharmaceutical products, there have been numerous reports of mislabeled weight-loss dietary supplements containing sibutramine.

Cardiogenic shock in a 28-year-old woman associated with sibutramine use.

A 28-year-old woman collapsed in her home, and her companion rushed to call emergency services. Upon arrival, a physician performed CPR and endotracheal intubation, successfully restoring her voluntary heart rhythm. However, while en route to the hospital, ventricular fibrillation recurred. Despite the restoration of her voluntary rhythm through electrical defibrillation, she remained in a comatose state, which eventually led to multiple organ failures. Family members revealed that she had a 2-month history of taking diet pills. Histological examination revealed cardiomyocyte necrosis, contraction band necrosis, interstitial hemorrhage, collagen deposition, interstitial fiber proliferation, and myofiber remodeling. Analysis of blood and urine using GC-MS and LC-MS detected sibutramine and its primary metabolites, M1 and M2, which were consistent with the composition of the medication she was taking. The deceased was in good health with no underlying heart disease. The above information confirmed that the cause of her death was sibutramine.

Pharmacotherapy for obesity: moving towards efficacy improvement.

Obesity is a chronic, recurring, progressive disease and a major public health problem associated with several other diseases that lead to disability, morbidity, and mortality. The prevalence of obesity has increased at pandemic levels, along with increasing weight-related comorbidities and deaths worldwide. Lifestyle interventions alone provide clinically significant long-term weight loss in only a small proportion of individuals, and bariatric surgery is not suitable or desirable for all patients. Historically, anti-obesity medications achieved a mean efficacy with weight loss between 5 and 10%, which significantly impacted several comorbidities and risk factors, but the average efficacy of these medications remained lower than that expected by both patients and health care professionals and eventually curbed long-term use. Moreover, there is no direct evidence on the impact of anti-obesity medications on cardiovascular outcomes. Semaglutide is a newer anti-obesity medication that changes the overall landscape, as phase 3 studies show a mean weight loss near the 15% threshold and significant proportions of patients with a weight loss of greater than 20%. In this review, we focus on the currently available anti-obesity medications, discuss the results of semaglutide, and present perspectives on the future of obesity treatment after semaglutide.

Treatment with Antiobesity Drugs in Weight Regain After Bariatric Surgery: a Retrospective Cohort Study.

BACKGROUND: Bariatric surgery is the most efficient treatment for obesity. However, in some cases, weight regain can occur. Currently, it is unknown the best antiobesity medication (AOM) for such clinical situation. This study aims to evaluate the effect of AOM in patients with weight regain after bariatric surgery. METHODS: A retrospective cohort study from December 2010 to July 2019 with patients submitted to bariatric surgery that had weight regain and received AOM for at least 2 years. RESULTS: Of 96 patients that had weight regain in the analyzed period and received AOM, 16 were excluded from the analysis due to non-compliance (n = 7), treatment failure (n = 5), intolerable side effects with all available AOM (n = 2), or interaction with other medications (n = 2). Eighty patients were included in the analysis. The mean age was 59.0 ± 10.1 years, 88.8% were female, 91.2% white, and most of them were submitted to gastric bypass (87.6%). The mean preoperative and nadir weight after surgery were 127.9 ± 25.5 kg and 84.7 ± 22.8 kg, respectively. At the initiation of AOM, the mean baseline weight was 99.4 ± 23.1 kg. After 2 years of follow-up, there was significant weight loss in the groups treated with topiramate-alone (- 3.2 kg), topiramate plus sibutramine (- 6.1kg), and orlistat-alone or in combination (- 3.9kg). No statistical difference was observed in the sibutramine-alone group. CONCLUSION: Topiramate (alone or associated with sibutramine) and orlistat (alone or in combination) promoted significant weight loss after 2 years of use in patients submitted to bariatric surgery with weight regain.

Fabrication of a simple 3D-printed microfluidic device with embedded electrochemiluminescence detection for rapid determination of sibutramine in dietary supplements.

The design and fabrication of a simple 3D-printed platform with embedded electrochemiluminescence (ECL) detection for sibutramine determination is described. The microfluidic platform was fabricated by the fused deposition 3D-printing technique with polylactic acid filament, facilitated by computer-aided design (CAD). A three-electrode system was integrated into the device using graphene carbon paste as a working electrode, Ag/AgCl wire as a reference, and a graphite rod as a counter electrode. A further modification was carried out by applying bimetallic Au-Pt nanoparticle-supported multi-walled carbon nanotubes (MWCNT-Au-Pt) on the working electrode surface to enhance the electrocatalytic performance by exploiting the unique properties of nanomaterials. The analytical feasibility of the CAD-ECL sensor was tested through its application for the determination of sibutramine in dietary supplements. Under the optimized conditions, based on the enhancing effect of luminol emission, the device exhibited a linear calibration curve of the logarithmic sibutramine concentration versus ECL intensity in the range 5 × 10-3 to 1 ng mL-1. The limit of detection was 3 pg mL-1 with a relative standard deviation of 1.7% (n = 15). The 3D-printed prototype can be successfully applied to a small-scale analysis in a simple and cost-effective approach.

An Indonesian slimming drug with undeclared ingredients causing harm.

This paper reports the presence of undeclared drugs in the herbal slimming supplement Sulami®. The four cases of the adverse drug reactions related to Sulami® were reported to the Dutch Pharmacovigilance Centre (Lareb) or the Dutch Poisons Information Centre (DPIC). The analysis of all four collected samples revealed adulteration with sibutramine and canrenone. Both drugs can cause serious adverse drug reactions. From a legal point of view, it is clear that Sulami® does not meet the legal requirement for safety. As defined in the European General Food Law Regulation, food business operators are responsible for food safety. This also applies to online store owners who sell herbal preparations. Thus, it is clear that it is forbidden to sell Sulami® on the European and Dutch market. Collaboration between involved national authorities makes it possible to identify risky products. This allows the nationally responsible regulators to take targeted action. They can call on users to report sell points what makes it possible to arrest the sellers and confiscate the dangerous products. Beyond the national, also, the European enforcement organizations should take legal measures where possible, to protect public health. The Heads of Food Safety Agencies Working Group on Food Supplements "an Initiative on European level" is a good example of efforts to improve consumer safety.

Simultaneous detection of sibutramine and phenolphthalein in a diet jelly health food product that caused health problems.

The Public Health Center in Chiba Prefecture, Japan, received a consultation from a resident of Chiba Prefecture who consumed a diet jelly health food product and experienced health problems. To investigate the cause of the health problems, we examined the two food products for the presence of pharmaceutical ingredients. A screening analysis using ultra-high-performance liquid chromatography with a photodiode array detector (UPLC-PDA) indicated the presence of sibutramine and phenolphthalein in the food product. Analysis using an ultra-high-performance liquid chromatography-quadrupole-Kingdon trap mass spectrometer (UHPLC-Q-Kingdon trap MS) confirmed the presence of sibutramine and phenolphthalein. Quantitative analysis using UPLC-PDA showed that sibutramine and phenolphthalein were present at 15 and 16 mg/bag and 2.4 and 2.6 mg/bag, respectively. According to the drug insert for sibutramine capsules in the United States, the recommended medicinal dose of sibutramine should not exceed 15 mg/day, and the amount ingested in the present case exceeded that value. The present study results indicated that ingestion of the jelly health food product may cause health problems.

Quantitation of sibutramine in human hair using gas chromatography-isotope dilution tandem mass spectrometry.

PURPOSE: An analytical method for quantitation of sibutramine in human hair using gas chromatography (GC)-isotope dilution tandem mass spectrometry (MS/MS) was newly established. In this article, a case is presented, in which a 3.5-year-old male child accidentally ingested chocolate-like product containing sibutramine, showing various symptoms; he could survived the crisis. About 1 month after the incident, his scalp hair sample was subjected to analysis for the causative sibutramine. METHOD: After cryo-grinding for the hair sample, target compound was extracted with methanol, and the solvent layer was evaporated to dryness. The residue was reconstituted in methanol and analyzed by GC-MS/MS, using the selected reaction monitoring (SRM) mode with a deuterated isotope internal standard. RESULTS: The substance was identified as sibutramine; its concentration in the hair sample of the child was 58.6 pg/mg. The calibration curve of sibutramine in hair samples had a good linear relationship in the concentration range of 20-200 pg/mg (r > 0.99); the extraction recovery rate 85.2-91.8%; the interday and intraday precision and accuracy (bias) examined not greater than 9.6%. Sibutramine in human hair had good stability under 3 different storage conditions at room (20 °C), refrigerated (4 °C) and frozen ( - 20 °C) temperatures for at least 7 days. CONCLUSIONS: It should be expected that the method established in this study would contribute to rapid determinations of sibutramine. To our knowledge, this is the first report describing quantitation of sibutramine in an authentic human hair sample by GC-MS/MS.

Assessment of redox state and biochemical parameters of salivary glands in rats treated with anti-obesity drug sibutramine hydrochloride.

OBJECTIVES: To investigate the effects of anti-obesity drug sibutramine hydrochloride (SB) on redox state and biochemical parameters in the salivary glands. MATERIALS AND METHODS: Adult male Wistar rats were randomly divided into the following groups (n = 8 per group): control rats treated with vehicle (C) and rats treated with SB (10 mg/kg/day) by intragastric gavage for 28 days. The parotid (PG) and submandibular (SMG) glands were processed using histomorphometric analysis, and total protein, amylase, mucin, and oxidative damage to lipids were determined by measuring the formation of thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC), uric acid (UA), total glutathione (tGSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and AKT phosphorylation. RESULTS: SB decreased the acinar area, and increased the stromal area in PG, while no effect on the morphometric parameters was observed in SMG. SB also increased oxidative damage to lipids (TBARs). The SB group showed lower total protein, amylase, TAC, UA, tGSH, SOD, CAT, and GPx than the C group in PG, while in SMG, SB decreased total protein, mucin, tGSH, SOD, CAT, and GPx. However, increased AKT phosphorylation observed in both salivary glands suggests that SB exerts low-intensity oxidative stress. CONCLUSIONS: SB impaired enzymatic and non-enzymatic antioxidant defenses in the salivary glands of rats. CLINICAL RELEVANCE: Chronic treatment with SB could mitigate salivary gland dysfunction due to disturbance of redox state.

Pharmacologically induced weight loss is associated with distinct gut microbiome changes in obese rats.

BACKGROUND: Obesity, metabolic disease and some psychiatric conditions are associated with changes to relative abundance of bacterial species and specific genes in the faecal microbiome. Little is known about the impact of pharmacologically induced weight loss on distinct microbiome species and their respective gene programs in obese individuals. METHODOLOGY: Using shotgun metagenomics, the composition of the microbiome was obtained for two cohorts of obese female Wistar rats (n = 10-12, total of 82) maintained on a high fat diet before and after a 42-day treatment with a panel of four investigatory or approved anti-obesity drugs (tacrolimus/FK506, bupropion, naltrexone and sibutramine), alone or in combination. RESULTS: Only sibutramine treatment induced consistent weight loss and improved glycaemic control in the obese rats. Weight loss was associated with reduced food intake and changes to the faecal microbiome in multiple microbial taxa, genes, and pathways. These include increased ß-diversity, increased relative abundance of multiple Bacteroides species, increased Bacteroides/Firmicutes ratio and changes to abundance of genes and species associated with obesity-induced inflammation, particularly those encoding components of the flagellum and its assembly. CONCLUSIONS: Sibutramine-induced weight loss in obese rats is associated with improved metabolic health, and changes to the faecal microbiome consistent with a reduction in obesity-induced bacterially-driven inflammation.

Sibutramine-Induced Nonischemic Cardiomyopathy.

Within the past 20 years, the global pandemic of obesity and associated life-threatening comorbidities significantly promoted the development and intervention of anti-obesity pharmacotherapy. Sibutramine hydrochloride monohydrate, formerly sold under the brand name Meridia and Reductil among others, is an anti-obesity, selective serotonin, and norepinephrine reuptake inhibitor drug that suppresses appetite and reduces body weight in conjunction with lifestyle modifications. However, since 2010, it has been discontinued in a majority of countries such as the United States and European Union due to an associated increase in cardiovascular events such as hypertension, tachycardia, arrhythmias, and myocardial infarction. Thus, this article illustrates a case of sibutramine-induced nonischemic cardiomyopathy, including details of evaluation, management, and monitoring of patient progress. Herein, we present a case report of a 19-year-old male with no prior medical conditions who presented to the emergency department after being found in a state of cardiac arrest (pulseless ventricular fibrillation) with consequent intubation in the field. Upon admission, cardiac catheterization and echocardiography revealed patent coronary arteries with a reduced ejection fraction of approximately 15%-20%. Acute systolic heart failure secondary to nonischemic cardiomyopathy was treated with standard medical management. In addition, due to continued episodes of non-sustained ventricular tachycardia, the patient also underwent a subcutaneous implantable cardioverter-defibrillator (ICD) placement.

Suicide Attempt in a Patient with Sibutramine Associated Psychosis.

Sibutramine is a serotonin-norepinephrine-dopamine reuptake inhibitor, initially developed as a potential antidepressant and later approved for the management of obesity. Sibutramine use is also associated with psychiatric symptoms, namely mania, panic attacks, and, less frequently, psychosis. We report the case of a 32-year-old man, admitted to our hospital due to a suicide attempt in the context of sibutramine-associated psychosis. The symptoms remitted completely after discontinuation of sibutramine and a brief period of antipsychotic medication. The aim of this manuscript is to highlight the importance of the recognition of sibutramine-associated psychosis, to discuss the possible pathophysiology and the proper clinical and therapeutic management.

A sibutramina é um inibidor não seletivo da recaptação de serotonina-noradrenalina-dopamina, inicialmente desenvolvido como potencial antidepressivo e posteriormente aprovado para o tratamento da obesidade. O uso de sibutramina está também associado ao aparecimento de sintomas psiquiátricos como mania, ataques de pânico e, com menor frequência, psicose. Relatamos um caso de um homem de 32 anos, internado no nosso hospital devido a uma tentativa de suicídio no contexto de uma psicose associada à sibutramina. Os sintomas remitiram completamente após a descontinuação da sibutramina e um breve período de terapêutica antipsicótica. O objetivo deste artigo é destacar a importância do reconhecimento da psicose associada à sibutramina, discutir a sua possível fisiopatologia e o seu apropriado manejo clínico e terapêutico.

Adulteration of Weight Loss Supplements by the Illegal Addition of Synthetic Pharmaceuticals.

Weight loss supplements that have illegal additives of pharmaceutical drugs or analogues have additional health risks, and customers may not be aware of what they are taking. This research is an essential investigation and quantification of illegally added pharmaceuticals or prescription medications, specifically fluoxetine, phenolphthalein, and sibutramine, in herbal weight loss supplements offered for sale in the United Arab Emirates (UAE). In this case, 137 weight loss supplements were collected and analyzed in this study. Reversed-phase high-performance liquid chromatography with UV absorption detection coupled to tandem mass spectrometry (RP-HPLC-MS/MS) analyses were used to determine the presence of the pharmaceutical chemicals. Among the weight loss supplements, 15.3% (95% CI: 9.2-21.4) contained undeclared sibutramine, 13.9% (95% CI: 8.01-19.7) contained undeclared phenolphthalein, and 5.1% (95% CI: 1.4-8.8) contained undeclared fluoxetine. Amongst all weight loss supplements, 17.5% (95% CI: 11.07-24) contained significant concentrations of either sibutramine, phenolphthalein, or fluoxetine. Whilst weight loss herbal supplements offered for sale in the UAE have relatively low percentages of undeclared pharmaceuticals, many people take several different supplements daily and may encounter quite high levels of combined exposure to toxic compounds.

New Serotonin-Norepinephrine Reuptake Inhibitors and Their Anesthetic and Analgesic Considerations.

Serotonin-norepinephrine reuptake inhibitors (SNRIs) inhibit the presynaptic neuronal uptake of serotonin and norepinephrine and prolong the effects of the monoamines in the synaptic cleft within the central nervous system, leading to increased postsynaptic receptor activation and neuronal activities. Serotonin-norepinephrine reuptake inhibitors can have multiple clinical indications, including as the first-line agents for the management of depression and anxiety, and as analgesics in the treatment of chronic pain. The effects of reuptake inhibition of norepinephrine and serotonin are often dose-dependent and agent-dependent. There are five FDA-approved serotonin-norepinephrine reuptake inhibitors (desvenlafaxine, duloxetine, levomilnacipran, milnacipran and sibutramine) currently being marketed in the United States. As the COVID-19 pandemic significantly increased the incidence and prevalence of anxiety and depression across the country, there are significantly increased prescriptions of these medications perioperatively. Thus, anesthesiologists are more likely than ever to have patients administered with these agents and scheduled for elective or emergency surgical procedures. A thorough understanding of these commonly prescribed serotonin-norepinephrine reuptake inhibitors and their interactions with commonly utilized anesthetic agents is paramount. There are two potentially increased risks related to the continuation of SNRIs through the perioperative period: intraoperative bleeding and serotonin syndrome. SNRIs have some off-label uses, more new indications, and ever-increasing new applications in perioperative practice. This article aims to review the commonly prescribed serotonin-norepinephrine reuptake inhibitors and the current clinical evidence regarding their considerations in perioperative anesthesia and analgesia.

Metabolic analysis of the illegal analogues of anti-obesity drugs using LC-Q-TOF-MS/MS.

With an increase in the obese population, the indiscriminate demand for anti-obesity drugs for rapid weight loss or maintenance has grown. As a result, illegal substances that could induce unexpected negative health effects or fatal side effects are being produced and mixed into consumer products. In the present study, the metabolites of five major illegal anti-obesity drugs are analyzed for the first time. Our data can be utilized to identify related compounds and predict their toxicological effects. Didesmethylsibutramine, desmethylsibutramine, homosibutramine, chlorosibutramine, and benzylsibutramine were metabolized in in vitro and in vivo models, and the metabolites were identified using liquid chromatography quadrupole-time of flight mass spectrometry (LC-Q-TOF-MS) and tandem mass spectrometry (LC-Q-TOF-MS/MS). The in vivo metabolite analysis was carried out using urine and feces samples from rats, and the in vitro metabolite analysis was performed by incubating the analogues with human liver microsomes. We found that each sibutramine analogue was metabolized into several constituents: 2 (M1-2), 5 (M1-5), 11 (M1-11), 7 (N1-7), and 5 (O1-5). In conclusion, our metabolic study could be used for toxicological detection of illegal obesity treatments and metabolite identification in forensic cases.

Interrelated In Vitro Mechanisms of Sibutramine-Induced Cardiotoxicity.

Consumption of illicit pharmaceutical products containing sibutramine has been reported to cause cardiovascular toxicity problems. This study aimed to demonstrate the toxicity profile of sibutramine, and thereby provide important implications for the development of more effective strategies in both clinical approaches and drug design studies. Action potentials (APs) were determined from freshly isolated ventricular cardiomyocytes with whole-cell configuration of current clamp as online. The maximum amplitude of APs (MAPs), the resting membrane potential (RMP), and AP duration from the repolarization phases were calculated from original records. The voltage-dependent K+-channel currents (IK) were recorded in the presence of external Cd2+ and both inward and outward parts of the current were calculated, while their expression levels were determined with qPCR. The levels of intracellular free Ca2+ and H+ (pHi) as well as reactive oxygen species (ROS) were measured using either a ratiometric micro-spectrofluorometer or confocal microscope. The mechanical activity of isolated hearts was observed with Langendorff-perfusion system. Acute sibutramine applications (10-8-10-5 M) induced significant alterations in both MAPs and RMP as well as the repolarization phases of APs and IK in a concentration-dependent manner. Sibutramine (10 µM) induced Ca2+-release from the sarcoplasmic reticulum under either electrical or caffeine stimulation, whereas it depressed left ventricular developed pressure with a marked decrease in the end-diastolic pressure. pHi inhibition by sibutramine supports the observed negative alterations in contractility. Changes in mRNA levels of different IK subunits are consistent with the acute inhibition of the repolarizing IK, affecting AP parameters, and provoke the cardiotoxicity.

Visual upconversion nanoparticle-based immunochromatographic assay for the semi-quantitative detection of sibutramine.

Immunochromatographic assay (ICA) has been used widely for the onsite monitoring of illegal additives due to its simplicity, speed, and low cost. However, a scanner is commonly required for ICA to achieve quantitative results. In this work, we developed a visual semi-quantitative ICA for sibutramine, a banned additive in diet foods, without the need for a scanner for measurement. Monoclonal antibodies specific for sibutramine were raised and conjugated with upconversion nanoparticles (UCNPs) as the luminescent tracer. ICA was developed by employing multiple test lines to achieve the semi-quantitative detection of sibutramine. Based on the optimal conditions, the cutoff levels (limit of quantitation, LOQ) of T1 line, T2 line, T3 line, and T4 line were 0.02 µg/mL, 0.15 µg/mL, 1.0 µg/mL, and 7.5 µg/mL, respectively, in buffer system. The ICA demonstrated a LOQ at 0.2 mg/kg for sibutramine in diet food samples. The assay (including pretreatment) can be finished within 30 min without the aid of other instruments, except a laser pen. No false positive or false negative results were observed. The results indicated that the proposed method was reliable, simple, and rapid for the screening of sibutramine abuse in diet food samples.

Impact of timing of the anorexigen sibutramine administration on reproductive end-points of male rats.

Sibutramine is a non-selective serotonin-norepinephrine reuptake inhibitor orally administered for weight loss. In a previous study, we showed pharmacological mechanisms involved in the reduction of sperm quality and fertility of rats exposed for 30 days to this anorexigen in the light phase of the light-dark (l/d) cycle. It is already known that rodents are nightlife animals, with higher metabolic activity during the dark phase than in the light phase of the light-dark (l/d) cycle. Thus, the present study aimed to investigate whether the deleterious effects on reproductive parameters after sibutramine administration would be enhanced after a shorter period of exposure during the dark phase of the l/d cycle. For this, adult male Wistar rats were treated with sibutramine (10 mg/kg/d) or vehicle for 15 days during the dark phase of the l/d cycle. Sibutramine treatment decreased final body and reproductive organ weights, as well as serum testosterone levels. Sperm transit time through the epididymis was accelerated, and sperm concentration and motility were diminished in the sibutramine-exposed rats. The decrease in sperm concentration was also verified in the epididymal histological sections. In conclusion, the deleterious effects of sibutramine on reproductive parameters of male rats were enhanced when the exposure occurred in the dark phase of the l/d cycle, even after a short exposure duration. Our results reinforce the impact of timing on drug therapeutic action.