Dexfenfluramine in obese Chinese NIDDM patients. A placebo-controlled investigation of the effects on body weight, glycemic control, and cardiovascular risk factors

The effect of weight loss on health-related quality of life: systematic review and meta-analysis of randomized trials

The aim of this study was to examine the effect of weight loss on health-related quality of life (HRQL) in randomized controlled intervention trials (RCTs). MEDLINE, HealthStar and PsycINFO were searched. RCTs of any weight loss intervention and 20 HRQL instruments were examined. Contingency tables were constructed to examine the association between statistically significant weight loss and statistically significant HRQL improvement within five HRQL categories. In addition, Short Form-36 (SF-36) outcomes were pooled using random-effects models. Fifty-three trials were included. Seventeen studies reported statistically significant weight loss and HRQL improvement. No statistically significant associations between weight loss and HRQL improvement were found in any contingency table. Because of suboptimal endpoint reporting, quantitative data pooling could only be performed using 25% of SF-36 trials in any one model. Significant improvements in physical health were found: mean difference 2.83 points, 95% CI 0.55-5.1, for the physical component score, and mean difference 6.81 points, 95% CI 2.99-10.63, for the physical functioning domain score. Conversely, no significant improvements in mental health were found. No significant association was found between weight loss and overall HRQL improvement. Weight loss may be associated with modest improvements in physical, but not mental, health.

Screening the receptorome reveals molecular targets responsible for drug-induced side effects: focus on ‘fen–phen’

The in vitro pharmacological profiling of drugs using a large panel of cloned receptors (e.g., G protein-coupled receptors, ligand-gated ion channels, Na(+)-dependent monoamine transporters), an approach that has come to be known as 'receptorome screening', has unveiled novel molecular mechanisms responsible for the actions and/or side effects of certain drugs. For instance, receptorome screening has been employed to uncover novel molecular targets involved in the actions of antipsychotic medications and the hallucinogenic mint extract salvinorin A. This review highlights the recent application of receptorome screening to discover why the anorexigen fenfluramine causes serious cardiopulmonary side effects. Receptorome screening has implicated N-deethylation of fenfluramine and serotonin 5-hydroxy-t-ryptamine 2B receptors in the adverse effects of the drug; subsequent studies corroborated this finding. The results discussed highlight the utility of determining the potential activity of drugs -- and, importantly, of their in vivo metabolites -- at as many molecular targets as possible in order to reliably predict side effect profiles. Receptorome screening represents one of the most effective methods for identifying potentially serious drug-related side effects at the preclinical stage, thereby avoiding significant economic and human health consequences.

A structured review of randomized controlled trials of weight loss showed little improvement in health-related quality of life

OBJECTIVE

To estimate the effect of weight-loss interventions on health-related quality of life (HrQoL) in randomized controlled trials (RCTs); to conduct a meta-analysis of weight-loss treatment on depressive symptoms; and, to examine methodological and presentation issues that compromise study validity.

STUDY DESIGN AND SETTING

We conducted a structured review of 34 RCTs with weight-loss interventions that reported the relationship between HrQoL and treatment at two or more time points. We also evaluated study quality.

RESULTS

Trials lasted 6 weeks to 208 weeks and evaluated behavioral, surgical, or pharmacologic interventions. Nine of 34 trials showed HrQoL improvements in generic measures. Obesity-specific measures were more likely to show improvement in response to treatment than non-obesity-specific measures. Meta-analysis showed no treatment effect on depressive symptoms. Most trials tracked loss to follow-up and conducted intent-to-treat analysis, but only four trials concealed recruitment staff to randomization and 14 blinded the investigation team to randomization.

CONCLUSION

HrQoL outcomes, including depression, were not consistently improved in RCTs of weight loss. The overall quality of these clinical trials was poor. Better-designed RCTs using standardized HrQoL measures are needed to determine the extent to which weight loss improves HrQoL.

Pharmacotherapy of type 2 diabetes mellitus

OBJECTIVE

To review the drug treatments and some of the popular, nontraditional remedies now available for type 2 diabetes mellitus, as well as selected investigational agents; to describe each medication's place in the overall approach to treatment.

DATA SOURCES

English-language journals, abstracts, review articles, and newspaper accounts.

DATA SYNTHESIS

In the past five years, there has been tremendous progress in the pharmacotherapy of diabetes, particularly type 2 diabetes. Several new agents have entered the clinical arena, and many more are in the late stages of investigation leading to approval. Sulfonylureas stimulate the production and release of insulin; these drugs must be used in patients with an intact pancreas. The meglitinides are nonsulfonylurea agents that are also insulin secretagogues. Unlike the sulfonylureas, repaglinide appears to require the presence of glucose to close the adenosine triphosphate-sensitive potassium channels and induce calcium influx. Metformin reduces hepatic glucose production in some patients and increases peripheral glucose utilization, but its use is hampered by a high percentage of adverse reactions. Disaccharidase inhibitors effectively compensate for the defective early-phase insulin release by slowing the production of sugars from carbohydrates. Thiazolidinediones appear to activate peroxisome proliferator-activated receptor gamma, which is involved in the metabolism of lipids. Short-acting insulin and the role of weight-loss agents are also discussed.

CONCLUSIONS

The availability of new options for diabetes therapy provides a chance for successful therapy in a larger number of patients. However, it is important to consider how much true benefit these new forms of treatment will have on the diabetic community. The best choice for a patient remains controversial.

In obese individuals dexfenfluramine corrects molecular derangements reflecting insulin resistance

BACKGROUND

Circulating lymphocytes of obese individuals with and without type 2 diabetes have derangements of pyruvate dehydrogenase (PDH) that are described as reflecting a disorder underlying systemic insulin resistance, namely basal activity below normal and, in vitro, unresponsiveness to insulin at 33 pmol/l and activation at 330 pmol/l instead of activation and inhibition as in controls.

OBJECTIVE

To explore whether the above enzyme derangements are overcome in obese individuals on dexfenfluramine treatment, known to improve poor peripheral insulin sensitivity.

METHODS

Fifteen obese diabetic patients and 15 age-matched euglycaemic obese subjects with normal glucose tolerance were enrolled for a trial composed of two 21-day periods; in the first (D-21-D0), participants received a placebo, and in the second (D0-D21), dexfenfluramine (30 mg/day). At D-21, D0 and D21 participants were evaluated for weight, BMI, fasting glycaemia (FG), fasting insulinaemia (FI), fasting insulin resistance index (FIRI), area under the glycaemic (G-AUC) and insulinaemic (I-AUC) curves from an OGT test, and for PDH activity assayed in their circulating lymphocytes before (basal activity) and after incubation with 33 or 330 pmol/l insulin. At D2, basal PDH activity and clinical parameters were assayed.

RESULTS

In both groups of participants at D0 all parameters tested were constant with respect to D-21; at D2, only basal PDH activity rose significantly; at D21, basal and insulin stimulated PDH activities were normalized and weight decreased significantly, as did FG, FI, FIRI and G-AUC in the diabetic, and FI, FIRI, G-AUC and I-AUC in the non-diabetic participants.

CONCLUSION

In obese, non-diabetic and diabetic individuals on dexfenfluramine treatment, amelioration of clinical parameters and indexes of poor insulin sensitivity of blood glucose homeostasis are preceded by correction, in their circulating lymphocytes, of PDH derangements described as reflecting a disorder underlying insulin resistance.

Antiobesity pharmacotherapy in the management of type 2 diabetes

Obesity is a well-known risk factor for the development of Type 2 diabetes mellitus. The management of the obese diabetic patient remains a challenge for the clinician but, in any case, weight reduction should be considered as a key objective. In this respect, several antiobesity drugs have demonstrated potential. However, while fenfluramine and dexfenfluramine have been shown to promote weight loss and to directly improve insulin sensitivity, being two mechanisms contributing to better blood glucose control in obese Type 2 diabetic patients, they were recently withdrawn due to safety problems. Sibutramine, a new selective norepinephrine and serotonin reuptake inhibitor, promotes weight loss by decreasing food intake, an effect which leads to a mild improvement (significant in patients losing > or =5% of initial body weight) of blood glucose control in obese diabetic patients. Similarly, orlistat, a selective gastrointestinal lipase inhibitor which increases faecal fat losses, enhances diet-induced weight reduction and improves both blood glucose control and vascular risk profile, especially dyslipidaemia, in obese Type 2 diabetic patients. Further studies are required to better identify good responders to pharmacotherapy and specify the role of antiobesity agents in the overall long-term management of obese subjects with Type 2 diabetes. Other novel pharmacological approaches deserve further consideration, for instance beta-3 agonists aiming to increase energy expenditure, drugs interfering with tumor necrosis factor-alpha (TNF-alpha) or free fatty acid release by the adipose tissue or agents that slow gastric emptying. However, until now, results regarding efficacy and/or safety have been disappointing or preliminary in humans.

Pharmacological intervention: the antiobesity approach

Reduction in overweight and obesity management have been shown to be important in the treatment of diabetes. Even modest weight loss produces important metabolic benefits if maintained over the long term. Thus a pharmacotherapeutic agent that could produce a maintained weight loss, and had a good safety profile, would revolutionize the treatment of type II (non-insulin-dependent) diabetes. Two obesity management agents, orlistat and sibutramine, are expected shortly for the long-term treatment of obesity. These agents have been shown to be effective in 1-2-year-long studies in obese, non-diabetic patients. They produced significant improvements in weight loss compared with placebos. The efficacy of these obesity management agents has also been demonstrated in short-term studies in patients with type II diabetes. As yet, however, few studies have investigated the long-term effects of these treatments in diabetic patients. Obese patients with type II diabetes receiving 12 months of dexfenfluramine therapy showed greater reductions in weight, fasting blood glucose and HbA1c levels than the controls. A 1-year study of orlistat treatment for patients with type II diabetes revealed substantial benefits in glycaemic control, even though weight loss was only moderate. A 1-year treatment with orlistat also substantially prevented the conversion of impaired glucose tolerance into type II diabetes (conversion rate 2.6% in the orlistat group versus 10.4% in the placebo group). Encouraging results have also been reported from studies on orlistat and sibutramine in non-diabetics, with beneficial effects seen for weight loss and other diabetes risk factors. Antiobesity pharmacotherapy therefore appears to offer a realistic option for the prevention of diabetes, although further studies are required to determine its efficacy.