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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Combination drug therapy can effectively treat the problem of obesity. The most commonly used combination is a mix of fenfluramine and phentermine. Fenfluramine inhibits the reuptake of serotonin and acts on the hypothalmic appetite control center, while phentermine acts as an appetite suppressant. These drugs along with diet and exercise effectively help people to lose weight with few side effects. However, there are several anesthetic considerations when providing anesthesia services for patients on the fenfluramine and phentermine regimen. Problems of hypotension on induction, hypoglycemia, hyperthermia, and pulmonary hypertension have been reported in the literature. Recently, dexfenfluramine (Redux) was approved by the U.S. Food and Drug Administration. It is the dextrostereoisomer of fenfluramine and is believed to produce the same weight loss with less side effects. Anesthesia providers must understand the potential risks involved when administering a general anesthetic to these patients.
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PMID:Anesthetic considerations for the new antiobesity medications. 923 2

Fenfluramine (FE) is a halogenated amphetamine derivative used in the treatment of obesity and thought to induce serotonin (5-HT) release from nerve terminals and to reduce re-uptake. However, other pathways may also be involved. In this work, the effects of FE on the major striatal afferent systems, and the possible interactions of these systems in FE-induced striatal expression of Fos, were studied by lesion of the serotonergic and/or dopaminergic system and administration of NMDA glutamate (MK-801) or D1 dopamine (SCH-23390) receptor antagonists. Both the D1 and NMDA receptor antagonists suppressed Fos expression in response to FE almost entirely. FE-induced Fos expression was also dramatically reduced 24 h after 6-hydroxydopamine (6-OHDA) lesion of the dopaminergic system. However, the reduction was not so marked after chronic 6-OHDA lesion, probably due to compensatory changes. Chronic (5,7-dihydroxytryptamine injection, 4 weeks before) or acute (p-chlorophenylalanine injection) lesion of the serotonergic system led to a marked reduction in Fos expression in response to FE (decrease of about 50%). After simultaneous chronic lesion of both serotonergic and dopaminergic systems, a considerable number of Fos-positive nuclei were still observed (decrease of about 70% in the dorsal and dorsomedial regions). The FE-induced expression of Fos was almost totally suppressed (decrease of about 95% in the dorsal and dorsomedial regions) after simultaneous acute lesion. Our results indicate that FE-induced striatal expression of Fos is due in large measure to DA release and dopaminergic stimulation of D1 receptors. However, concurrent stimulation of NMDA glutamate receptors also appears to be essential, and 5-HT release (although not indispensable) doubles striatal Fos expression.
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PMID:Interaction between the serotonergic, dopaminergic, and glutamatergic systems in fenfluramine-induced Fos expression in striatal neurons. 941 20

Fenfluramine is an amphetamine analogue which has been widely used in the treatment of obesity. In rodents, non-human primates, and humans, fenfluramine is associated with some indices of neurotoxicity, as well as pulmonary hypertension and cardiac valve pathology. In the present study, d-fenfluramine was found to be cytotoxic to the serotonin (5-HT) transporter (5-HTT) expressing human placental choriocarcinoma cells. d-Fenfluramine caused DNA fragmentation and apoptosis. Apoptosis was not observed after the 5-HTT had been blocked by fluoxetine, indicating that intact 5-HTT function is required for d-fenfluramine to induce programmed cell death. These observations in a human cell line may reflect a possible mechanism associated with the risks of fenfluramine administration in several species, including humans.
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PMID:The appetite suppressant d-fenfluramine induces apoptosis in human serotonergic cells. 980 3

Fenfluramine + phentermine was a widely used combination for weight loss. Fenfluramine and phentermine are believed to act via serotonin and catecholamines, respectively. To what extent these drugs interact has not been well-established. We compared the anorectic efficacy of a range of doses of the combination (using dexfenfluramine instead of fenfluramine) relative to a range of doses of the individual drugs in 90 min sweetened milk intake tests in deprived and nondeprived rats. Results were plotted on isobolograms to determine whether the anorectic effects of the combination were either additive or synergistic. Collectively, the isobolographic analysis revealed that: (1) under acute conditions, dexfenfluramine and phentermine interact for the most part in a synergistic manner, and (2) with the exception of phentermine alone, deprivation state at time of testing did not alter the efficacy of the anorectics. These findings suggest that combined drug treatment for obesity is a theoretical approach that merits further investigation.
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PMID:Anorectic efficacy of the fenfluramine/phentermine combination in rats: additivity or synergy? 1041 30

Fenfluramine (FE) is a halogenated amphetamine derivative that has been used in the treatment of obesity. It has been suggested that the effects of FE on the striatum are mediated by serotonergic mechanisms. However, several major afferent systems may be involved, and administration of FE may be useful to study interactions between these systems. In this work, the effects of FE on striatopallidal neurons and the possible involvement of the major striatal afferent systems were studied in rats by determination of FE-induced changes in striatal levels of preproenkephalin (PPE) mRNA using in situ hybridization. Injection of FE induced a significant increase (60%) in striatal levels of PPE mRNA. This increase was blocked by pretreatment with the D(1) dopamine receptor antagonist SCH-23390 or with the NMDA glutamate receptor antagonist MK-801, or by lesion of the serotonergic system with 5,7-dihydroxytryptamine or p-chlorophenylalanine. In 6-hydroxydopamine lesioned rats, the lesion-induced increase in PPE mRNA levels was not affected by injection of FE, but was reduced by simultaneous serotonergic deafferentation. The results suggest that the serotonergic, glutamatergic, and dopaminergic system interact to increase striatal PPE mRNA levels after FE administration.
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PMID:Fenfluramine-induced increase in preproenkephalin mRNA levels in the striatum: interaction between the serotonergic, glutamatergic, and dopaminergic systems. 1065 25

Past and current drug therapies for weight loss are discussed. More than 50% of Americans can be categorized as overweight or obese. Obesity is associated with increased mortality and with comorbidities such as hypertension, hyperglycemia, dyslipidemia, coronary artery disease, and certain cancers. According to guidelines for identification, evaluation, and treatment of obesity, patients with a body mass index (BMI) of > or = 30 kg/m2 should attempt to lose weight. Patients with a BMI of > or = 25 kg/m2 plus two or more risk factors or patients with an excessive waist circumference plus two or more risk factors should also attempt to lose weight. The initial goal is a 10% weight reduction in six months achieved through lifestyle changes. If lifestyle changes alone are not effective, then drug therapy may be indicated. Pharmacotherapeutic options for obesity have decreased over the past few years. Fenfluramine, dexfenfluramine, and phenylpropanolamine have been withdrawn because of severe adverse effects, leaving only sympathomimetics, sibutramine, and orlistat as anorectics with FDA-approved labeling. Phentermine has been shown to cause a 5-15% weight loss if given daily or intermittently. Compared with sibutramine and orlistat, phentermine is cheaper, and specific formulations allow once-daily administration. However, phentermine is indicated only for short-term treatment, and tolerance often develops. Common adverse effects associated with phentermine are dry mouth, insomnia, increased blood pressure, and constipation. Sibutramine increases norepinephrine and serotonin levels in the CNS and should not be taken with many antidepressants because of the risk of increased norepinephrine and serotonin levels. Its use is also contraindicated in patients with cardiovascular disease. Orlistat is not systemically absorbed; therefore, it does not cause the systemic adverse effects or drug interactions of phentermine and sibutramine. Orlistat has a cholesterol-lowering effect not seen with other diet medications. However, the three-times-daily administration and frequent gastrointestinal effects limit its use. Sibutramine, phentermine, and orlistat have both positive and negative properties. Choosing among the medications will depend on concurrent disease states and medications, ease of administration, and cost.
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PMID:Pharmacologic options for the treatment of obesity. 1147 77

Fenfluramine-phentermine combination therapy ("fen-phen") became a popular treatment for obesity in the 1990s. Although this treatment causes cardiac toxicity, use of these medications has not previously been associated with seizures. We report five cases with apparent association between use of fenfluramine-phentermine and occurrence of seizures. Three patients with a history of childhood-onset idiopathic generalized epilepsy in remission experienced a recrudescence of seizures following treatment with fenfluramine-phentermine. Two patients presented with new-onset seizures in midlife following use of fenfluramine-phentermine, and seizures persisted following discontinuation of this therapy. One of these patients restarted fenfluramine-phentermine months later, and experienced recurrent seizures. The nature of the association between fenfluramine-phentermine and seizures is uncertain from this preliminary report. There may be a specific association with idiopathic generalized epilepsies, which appeared to be overrepresented in this case series. An effect of fen-phen on seizure threshold appears most likely; however, an epileptogenic effect cannot be excluded.
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PMID:Fenfluramine-Phentermine (Fen-Phen) and Seizures: Evidence for an Association. 1273 35

The anorexigen (+)-fenfluramine was used for treatment of obesity until the association of use with valvular heart disease and primary pulmonary hypertension. (+)-Fenfluramine has been found in Chinese and Korean slimming pills. The hepatic metabolite of (+)-fenfluramine, (+)-norfenfluramine, has affinity for 5-hydroxytryptamine (5-HT)(2A) and 5-HT(2B) receptors. We tested the hypothesis that (+)-norfenfluramine contracts arterial smooth muscle in a 5-HT receptor-dependent manner and acts as a pressor in the conscious rat. Isometric contraction experiments showed that (+)-norfenfluramine (10 nM, 100 microM) but not (+)-fenfluramine nor the isomer (-)-norfenfluramine caused concentration-dependent contraction in arteries [-log EC(50) (moles per liter), thoracic aorta = 5.77 +/- 0.09; renal artery = 6.29 +/- 0.02; mesenteric resistance artery = 5.70 +/- 0.06]. Contraction was dependent on the 5-HT(2A) receptor because ketanserin (10 nM) rightward shifted (+)-norfenfluramine response curves (aorta = 16-fold, renal artery = 26-fold, and resistance artery = >100-fold). Dependence on activation of 5-HT(2A) receptors and independence of (+)-norfenfluramine-induced contraction from stimulation of alpha-adrenergic receptors and the sympathetic nervous system was validated by demonstrating 1) unchanged contraction to (+)-norfenfluramine in arteries from chemically denervated rats; 2) a minimal effect of the alpha(1)-adrenergic receptor antagonist prazosin (100 nM) on contraction; and 3) antagonism by [6-methyl-l-(1-methylethy)ergoline-8beta-carboxylic acid 2-hydroxy-1 methylpropyl ester maleate] LY53857 [6-methyl-1-(1-methylethy)-ergoline-8beta-carboxylic acid 2-hydroxy-1 methylpropyl ester maleate], a 5-HT(2) receptor antagonist without alpha-receptor affinity. (+)-Norfenfluramine (10-300 microg/kg i.v.) caused a dose-dependent increase in mean arterial blood pressure in conscious rats, the maximum of which could be virtually abolished by ketanserin (3 mg/kg i.v.) but not prazosin (0.2 mg/kg i.v.). Our findings demonstrate for the first time that (+)-norfenfluramine is vasoactive and has the potential to increase blood pressure.
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PMID:The fenfluramine metabolite (+)-norfenfluramine is vasoactive. 1475 59

Overweight and obesity have been rising dramatically worldwide and are associated with numerous co-morbidities such as cardiovascular disease (CVD), type 2 diabetes mellitus, hypertension, certain cancers, and sleep apnea. In fact, obesity is an independent risk factor for CVD and CVD risks have also been documented in obese children. The majority of overweight and obese patients who achieve a significant short-term weight loss do not maintain their lower bodyweight in the long term. This may be due to a lack of intensive counseling and support from a facilitating environment including dedicated healthcare professionals such as nutritionists, kinesiologists, and behavior specialists. As a result, there has been a considerable focus on the role of adjunctive therapy such as pharmacotherapy for long-term weight loss and weight maintenance. Beyond an unfavorable risk factor profile, overweight and obesity also impact upon heart structure and function. Since the beginning, the quest for weight loss drugs has encountered warnings from regulatory agencies and the withdrawal from the market of efficient but unsafe medications. Fenfluramine was withdrawn from the market because of unacceptable pulmonary and cardiac adverse effects. Nevertheless, there is extensive research directed at the development of new anti-obesity compounds. The effect of these molecules on CVD risk factors has been studied and reported but information regarding their impact on the cardiovascular system is sparse. Thus, instead of looking at the benefit of weight loss on metabolism and risk factor management, this article discusses the impact of weight loss medications on the cardiovascular system. The potential interaction of available and potential new weight loss drugs with heart function and structure is reviewed.
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PMID:Impact of weight-loss medications on the cardiovascular system: focus on current and future anti-obesity drugs. 1769 68

The progressive ratio schedule of operant responding is a well utilised task for assessing the rewarding aspects of abused drugs and natural rewards including food. Interestingly, progressive ratio paradigms have mainly been neglected in the field of animal research in obesity. Among the most widely studied mouse models of obesity is the leptin-deficient ob/ob mouse, characterised by hyperphagia and obesity. To date there are no studies on the behaviour of these mice in progressive ratio responding, thus we sought to validate the utility of the progressive ratio paradigm in obese mice and demonstrate its sensitivity to an anorectic drug challenge. Ob/ob mice and their lean controls were tested in fixed ratio paradigms of different demand, extinction learning, and progressive ratio schedules with linear and exponential increments, followed by an anorectic drug challenge with fenfluramine (5 and 10 mg/kg). Obese animals showed equal fixed ratio-acquisition and -responding for ratios 1 and 3, but displayed lower responding in ratios 6 and 9. Interestingly, obese animals showed equal motivation to respond in progressive ratio schedules. Fenfluramine dose-dependently induced anorectic effects in both genotypes and reduced progressive ratio responding significantly. This study, for the first time, describes motivational food intake in an operant progressive ratio paradigm in ob/ob mice. Leptin deficiency did not alter appetitive learning or motivation in the progressive ratio. The utility and sensitivity of the progressive ratio task for studies on motivational food intake was demonstrated by a challenge with the anorectic agent fenfluramine.
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PMID:Progressive ratio responding in an obese mouse model: Effects of fenfluramine. 2072 62


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