Efficacy and safety of topiramate in combination with metformin in the treatment of obese subjects with type 2 diabetes: a randomized, double-blind, placebo-controlled study

Clinical effectiveness and predictors of response to topiramate plus lifestyle modification in youth with obesity seen in a weight management clinical setting

Introduction

Obesity affects approximately 20% of U.S. youth. Anti-obesity medications (AOMs) are promising lifestyle modification adjuncts for obesity treatment, and topiramate is commonly prescribed in pediatric weight management clinics. It is important to determine "real-world" effectiveness of AOMs and, given shifts towards personalized approaches, characteristics potentially predicting better or worse response. We therefore sought to describe clinical effectiveness from topiramate plus lifestyle modification, and to determine if baseline phenotypic characteristics are associated with better or worse response.

Methods

We performed a retrospective cohort study (2012-2020) among youth (<18 years old) followed in a U.S. academic-based weight management clinic. Baseline characteristics (i.e., body mass index (BMI), liver function tests, eating-related behaviors) and outcomes (%BMI of 95th percentile (%BMIp95), BMI, percent %BMI change, weight) were determined through review of electronic health records and clinic intake survey data.

Results

Among 282 youth prescribed topiramate plus lifestyle modifications (mean baseline age 12.7 years, %BMIp95 144%), %BMIp95 and percent BMI change were statistically significantly reduced at each time point (1.5-, 3-, 6-, and 12-month %BMIp95 reductions: -2.2, -3.9, -6.6, and -9.3 percentage points, respectively; percent BMI reduction: -1.2%, -1.9%, -3.2%, and -3.4%, respectively; all p<0.01). Considering multiple comparisons, no baseline characteristics statistically significantly predicted response at any time point.

Conclusions

We found that topiramate plus lifestyle modification reduced %BMIp95 and BMI among youth in a weight management clinical setting, and that no baseline characteristics evaluated were associated with response. These results should be considered preliminary given the observational nature of this study, and prospective studies are needed to further characterize clinical effectiveness and identify and confirm potential predictors of response.

Protective Effect of Topiramate against Diabetic Retinopathy and Computational Approach Recognizing the Role of NLRP3/IL-1β/TNF-α Signaling

The possible impact of topiramate against diabetic retinopathy (DREN) and its molecular mechanisms in relation to the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome has not been studied before. Thus, in the present study, we aimed to utilize a computational approach to investigate the possible protective effect of topiramate on experimental DREN and explore its impact on NLRP3/interlukin-1β signaling and brain-derived neurotrophic factor (BDNF) expression. Male albino mice were distributed to four experimental groups and assigned the following categorizations: (i) saline, (ii) diabetic, (iii) diabetic + topiramate 10 mg/kg and (iv) diabetic + topiramate 30 mg/kg. We observed shrinkage of total retinal thickness and elevation in retinal glutamate, malondialdehyde, NLRP3 and interlukin-1β but decreased glutathione (GSH) levels in the diabetic mice. Additionally, retinal ultra-structures in the diabetic group showed abnormalities and vacuolations in the pigmented epithelium, the photoreceptor segment, the outer nuclear layer, the inner nuclear layer and the ganglion cell layer (GCL). Mice treated with topiramate 10 or 30 mg/kg showed downregulation in retinal malondialdehyde, NLRP3 and interlukin-1β levels; improvements in the retinal pathologies; enhanced immunostaining for BDNF and improved ultra-structures in different retinal layers. Overall, the current results suggest topiramate as a neuroprotective agent for DREN, and future studies are warranted to further elucidate the mechanism of its protective action.

Topiramate (Topamax): Evolving Role in Weight Reduction Management: A Narrative Review

Obesity has emerged as a widespread disease with epidemic proportions, necessitating effective management to enhance the overall health outcomes of patients. Medical intervention for weight loss becomes necessary when diet and exercise prove ineffective, and topiramate emerges as a potential treatment option for this global problem. Currently approved as an anti-epileptic and migraine prophylaxis medication, topiramate is frequently utilized as adjunctive therapy for patients with mood and eating disorders, as well as for alcohol use disorders. Its multifaceted mechanisms of action contribute to reducing neuronal excitation and enhancing neuronal inhibition. Given its variety of mechanisms, topiramate shows several off-label outcomes, including weight loss, for patients prescribed this medication. Although the specific mechanism of action concerning weight loss remains uncertain, various hypotheses have been reported. Notably, topiramate may contribute to weight loss by reducing calorie intake, decreasing fat gain, and lowering triglyceride and cholesterol levels. Additionally, its impact on reward pathways associated with food could play a role. Multiple clinical studies have supported the use of topiramate as a weight-loss medication. Notably, the medication demonstrates effectiveness in reducing body weight across different dosages and sustaining weight loss over time, outperforming alternative weight loss methods. Moreover, it was generally well-tolerated in clinical studies, with few side effects observed. In conclusion, topiramate offers promising potential as a weight loss solution and can be a valuable addition to the range of treatment options for combating obesity.

Insights on Dietary Polyphenols as Agents against Metabolic Disorders: Obesity as a Target Disease

Obesity is a condition that leads to increased health problems associated with metabolic disorders. Synthetic drugs are available for obesity treatment, but some of these compounds have demonstrated considerable side effects that limit their use. Polyphenols are vital phytonutrients of plant origin that can be incorporated as functional food ingredients. This review presents recent developments in dietary polyphenols as anti-obesity agents. Evidence supporting the potential application of food-derived polyphenols as agents against obesity has been summarized. Literature evidence supports the effectiveness of plant polyphenols against obesity. The anti-obesity mechanisms of polyphenols have been explained by their potential to inhibit obesity-related digestive enzymes, modulate neurohormones/peptides involved in food intake, and their ability to improve the growth of beneficial gut microbes while inhibiting the proliferation of pathogenic ones. Metabolism of polyphenols by gut microbes produces different metabolites with enhanced biological properties. Thus, research demonstrates that dietary polyphenols can offer a novel path to developing functional foods for treating obesity. Upcoming investigations need to explore novel techniques, such as nanocarriers, to improve the content of polyphenols in foods and their delivery and bioavailability at the target sites in the body.

AGA Clinical Practice Guideline on Pharmacological Interventions for Adults With Obesity

BACKGROUND & AIMS

Pharmacological management of obesity improves outcomes and decreases the risk of obesity-related complications. This American Gastroenterological Association guideline is intended to support practitioners in decisions about pharmacological interventions for overweight and obesity.

METHODS

A multidisciplinary panel of content experts and guideline methodologists used the Grading of Recommendations Assessment, Development and Evaluation framework to prioritize clinical questions, identify patient-centered outcomes, and conduct an evidence synthesis of the following agents: semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate extended-release (ER), naltrexone-bupropion ER, orlistat, phentermine, diethylpropion, and Gelesis100 oral superabsorbent hydrogel. The guideline panel used the evidence-to-decision framework to develop recommendations for the pharmacological management of obesity and provided implementation considerations for clinical practice.

RESULTS

The guideline panel made 9 recommendations. The panel strongly recommended the use of pharmacotherapy in addition to lifestyle intervention in adults with overweight and obesity (body mass index ≥30 kg/m2, or ≥27 kg/m2 with weight-related complications) who have an inadequate response to lifestyle interventions. The panel suggested the use of semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate ER, and naltrexone-bupropion ER (based on moderate certainty evidence), and phentermine and diethylpropion (based on low certainty evidence), for long-term management of overweight and obesity. The guideline panel suggested against the use of orlistat. The panel identified the use of Gelesis100 oral superabsorbent hydrogel as a knowledge gap.

CONCLUSIONS

In adults with overweight and obesity who have an inadequate response to lifestyle interventions alone, long-term pharmacological therapy is recommended, with multiple effective and safe treatment options.

Treating the Chronic Disease of Obesity

Obesity is a treatable chronic disease. Primary care providers play an essential role in diagnosis, treatment, and comprehensive care of patients with obesity. In recent years, treatment approaches have rapidly evolved, increasing effective and safe therapies. In this review, we provide practical information on the care of patients with obesity with a focus on antiobesity pharmacotherapy within the context of currently available therapeutic modalities such as intensive lifestyle interventions and bariatric surgery.

Binge-Eating Disorder and Type 2 Diabetes: A Review

OBJECTIVE

To familiarize health care providers with diagnosis and treatment of binge-eating disorder (BED), a common comorbidity of type 2 diabetes (T2DM).

METHODS

Literature review of binge eating and T2DM. Key words used in search include BED, T2DM, obesity, and treatment.

RESULTS

The prevalence of BED in patients with T2DM appears to be much higher than the 2% to 3.5% prevalence seen in the general population. Studies suggest that up to 20% of patients with T2DM have an underlying eating disorder, the most common of which is binge eating. BED is probably underdiagnosed, even though there are multiple simple tools that providers can use to improve screening for the disorder. Though the relationship between BED and hemoglobin A1c control can vary, it appears that binge-eating behaviors can worsen metabolic markers, including glycemic control. Various medications used by patients with diabetes have been associated with new-onset BED, and treatment may be as simple as removing or replacing such agents. Several medications have been found to significantly reduce binge-eating frequency, and potentially, weight. Patients with BED generally benefit from psychotherapy, including cognitive behavioral therapy.

CONCLUSION

BED, only recently added to the International Classification of Disease-10 diagnostic list, is very common in patients with obesity and T2DM. The diagnosis is important to establish, as treatment or referral for treatment, could potentially improve many of the comorbidities and metrics of T2DM.

Effect of weight reduction on glycated haemoglobin in weight loss trials in patients with type 2 diabetes

AIM

To quantify the effect of weight loss on glycated haemoglobin (HbA1c) at group level, based on data from published weight loss trials in overweight and obese patients with type 2 diabetes (T2D).

METHODS

A systematic literature search in MEDLINE, EMBASE and Cochrane CENTRAL (January 1990 through December 2012) was conducted to identify prospective trials of energy-reduced diets, obesity drugs or bariatric surgery in adult, overweight and obese patients with T2D. Based on clinical data with follow-up from 3 to 24 months, a linear model was developed to describe the effect of weight reduction on HbA1c.

RESULTS

The literature search identified 58 eligible articles consisting of 124 treatment groups and 17 204 subjects, yielding a total of 250 data points with concurrent mean changes from baseline in weight and HbA1c. The model-based analyses indicated a linear relationship between weight loss and HbA1c reduction, with an estimated mean HbA1c reduction of 0.1 percentage points for each 1 kg of reduced body weight for the overall population. Baseline HbA1c was a significant covariate for the relationship between weight loss and HbA1c: high HbA1c at baseline was associated with a greater reduction in HbA1c for the same degree of weight loss. The collected trial data also indicated weight-loss-dependent reductions in antidiabetic medication.

CONCLUSIONS

At group level, weight loss in obese and overweight patients with T2D was consistently accompanied by HbA1c reduction in a dose-dependent manner. The model developed in the present study estimates that for each kg of mean weight loss, there is a mean HbA1c reduction of 0.1 percentage points. HbA1c-lowering is greater in populations with poor glycaemic control than in well controlled populations with the same degree of weight loss. This summary of data from previous trials regarding the effect of weight reduction on HbA1c may be used to support the design and interpretation of future studies that aim to demonstrate the efficacy of weight loss interventions for T2D treatment.

Pharmacotherapy of Obesity: Clinical Trials to Clinical Practice

PURPOSE OF REVIEW

This review provides an overview of the current state of drug therapy for obesity, with a focus on four new drug therapies-lorcaserin, phentermine/topiramate, naltrexone/bupropion, and liraglutide 3.0 mg-which have been approved by the US Food and Drug Administration (FDA) for long-term management of obesity since 2012. Topics discussed in this paper include rationale for pharmacotherapy, history of antiobesity drugs, and efficacy and safety data from randomized controlled trials with implications for clinical practice.

RECENT FINDINGS

Weight loss achieved by currently approved drugs ranges from approximately 3 to 9%, above and beyond weight loss with lifestyle counseling alone, after a year. Response and attrition rates in clinical trials indicate that the benefits of pharmacotherapy range from substantial for some patients, modest for others, and no benefits for others still. Decisions regarding selection of a suitable drug from the available pharmacotherapy options and duration of treatment should be based on the expected and observed benefit-to-risk balance and tailored to the needs of each individual patient using the principles of shared decision-making.

Topiramate monotherapy for weight reduction in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

AIMS

To conduct a systematic review with meta-analysis to determine the efficacy and safety of topiramate as monotherapy for weight reduction in patients with type 2 diabetes mellitus.

METHODS

We searched MEDLINE, Embase, and International Pharmaceutical Abstracts from inception to June 2015. We included randomized controlled trials that evaluated topiramate monotherapy versus control agents or placebo for weight loss in obese type 2 diabetes patients.

RESULTS

Of the 284 studies identified, 5 studies fulfilled the inclusion criteria. Topiramate decreased weight by a mean difference of 3.4kg (95% CI, -3.79 to -3.04) compared to placebo. Mean HbA1c reduction of -0.4% (95% CI, -0.58 to -0.32) and mean BMI reduction of -1.43kg/m(2) (95% CI, -1.83 to -1.03) were both significantly observed with topiramate (p<0.00001). Serious and total adverse events occurred more commonly among topiramate users, with a risk ratio for serious adverse events of 1.69 (95% CI, 1.00-2.87). All but one study had high risk of bias.

CONCLUSIONS

Topiramate monotherapy reduced weight in obese type 2 diabetes patients, but increased adverse events including serious adverse events. Given these safety concerns and the absence of data on clinically meaningful efficacy endpoints, clinicians should generally avoid use of topiramate alone for this indication.

Cardiovascular effects of phentermine and topiramate: a new drug combination for the treatment of obesity

Weight loss can reduce the increased cardiovascular risk associated with obesity. Pharmacotherapy is a recognized weight loss treatment option; however, cardiovascular safety issues with some previous weight loss drugs raise concerns for newly approved pharmacotherapies. Phentermine is approved for short-term obesity treatment in conjunction with lifestyle modifications, but is commonly used chronically. Topiramate, approved for treating epilepsy and preventing migraines, also induces weight loss. A single-dose combination of low-dose phentermine and topiramate extended-release was recently approved by the United States Food and Drug Administration as an adjunct to lifestyle intervention for the chronic treatment of overweight/obese adults. This review summarizes and evaluates the cardiovascular risk/benefit profile associated with phentermine and topiramate, individually and in combination. Cardiovascular data associated with long-term use of phentermine and topiramate extended-release indicate that this combination may be a safe and effective option for reducing weight in overweight/obese patients at low-to-intermediate cardiovascular risk.

Current pharmacotherapy for obesity: extrapolation of clinical trials data to practice

INTRODUCTION

When used prudently and in combination with lifestyle modification, pharmacotherapy has an important role in the management of obesity.

AREAS COVERED

This review covers targets for antiobesity drugs, challenges and limitations, failed translation of basic science to clinical practice, methodological and regulatory issues in clinical trials of pharmacotherapy, efficacy and risks of drugs currently approved for obesity, and clinical practice issues when using antiobesity drugs with emphasis on recently approved drugs.

EXPERT OPINION

Drugs currently approved for long-term therapy of obesity offer modest benefits for most patients, substantial benefits for some and no benefits for others. Numerous methodological problems including exclusion of the type of patients who are most often seen in clinical practices, inadequate enrollment of men and minorities, exclusion of patients taking antidepressants, high dropout rates, lack of follow-up after treatment discontinuation, and less than ideal imputation methods in data analysis limit the interpretation of clinical trials data and generalizability. Single-drug therapies offer small to moderate weight-loss benefits, but are generally better tolerated. Efficacy is enhanced with combination drug therapies, but so are the hazards. Clinicians should base their decisions on the expected and observed benefit-to-risk balance.

Evaluation of phentermine and topiramate versus phentermine/topiramate extended-release in obese adults

OBJECTIVE

A 28-week, randomized, controlled trial compared the combination of phentermine and topiramate extended-release (PHEN/TPM ER) with its components as monotherapies and with placebo in obese adults.

DESIGN AND METHODS

Subjects were randomized to placebo, phentermine 7.5 mg, phentermine 15 mg, topiramate ER 46 mg, topiramate ER 92 mg, PHEN/TPM ER 7.5/46 mg, or PHEN/TPM ER 15/92 mg. All subjects received lifestyle intervention counseling. Primary endpoints were percent weight loss (WL) and achievement of ≥5% WL.

RESULTS

At week 28, PHEN/TPM ER 7.5/46 (-8.5%) and 15/92 (-9.2%) achieved greater percentage WL versus placebo (-1.7%; P < 0.0001) and their respective monotherapies (P < 0.05). The percentage of subjects achieving ≥5% WL was 15.5% for placebo, 43.3% for phentermine 7.5, 46.2% for phentermine 15, 39.2% for topiramate ER 46, 48.6% for topiramate ER 92, 62.1% for PHEN/TPM ER 7.5/46, and 66.0% for PHEN/TPM ER 15/92. PHEN/TPM ER was generally well tolerated; comprehensive assessment of cognitive functions with the Repeatable Battery for Assessment of Neuropsychological Status revealed impairment only in the attention domain.

CONCLUSIONS

PHEN/TPM ER demonstrated greater WL when used in combination than when used as monotherapies, suggesting enhanced ability of the combination formulation to induce WL at doses lower than with available monotherapies.

An open-label drug-drug interaction study of the steady-state pharmacokinetics of topiramate and glyburide in patients with type 2 diabetes mellitus

BACKGROUND

Topiramate is approved for epilepsy and migraine headache management and has potential antidiabetic activity. Because topiramate and antidiabetic drugs may be co-administered, the potential drug-drug interactions between topiramate and glyburide (glibenclamide), a commonly used sulfonylurea antidiabetic agent, was evaluated at steady state in patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a single-center, open-label, phase I, drug interaction study of topiramate (150 mg/day) and glyburide (5 mg/day alone and concomitantly) in patients with T2DM. The study consisted of 14-day screening, 48-day open-label treatment, and a 7-day follow-up phase. Serial blood and urine were obtained and analyzed by liquid chromatography coupled mass spectrometry/mass spectrometry for topiramate, glyburide, and its active metabolites M1 (4-trans-hydroxy-glyburide) and M2 (3-cis-hydroxy-glyburide) concentrations. Pharmacokinetic parameters were estimated by model-independent methods. Changes in fasting plasma glucose from baseline and safety parameters were monitored throughout the study.

RESULTS

Of 28 enrolled patients, 24 completed the study. Co-administration of topiramate resulted in a significant (p < 0.05) decrease in the glyburide area under the concentration-time curve (25 %) and maximum plasma concentration (22 %), and reduction in systemic exposure of M1 (13 %) and M2 (15 %). Renal clearance of M1 (13 %) and M2 (12 %) increased during treatment with topiramate. Steady-state pharmacokinetics of topiramate were unaffected by co-administration of glyburide. Co-administration of topiramate and glyburide was generally tolerable in patients with T2DM.

CONCLUSION

Glyburide did not affect the pharmacokinetics of topiramate. Co-administration of topiramate decreased systemic exposure of glyburide and its active metabolites; combined treatment may require dosing adjustments of glyburide as per clinical judgment and glycemic control.

Clinical utility of phentermine/topiramate (Qsymia™) combination for the treatment of obesity

Qsymia™ (Vivus Inc, Mountain View, CA, USA), a combination of phentermine and delayed-release topiramate, has been available in the US since September 2012 for the treatment of obesity. Phentermine is an anorexigenic agent, which is approved for the short-term treatment of obesity, while topiramate is approved for nonweight loss indications - seizure disorders and migraine prophylaxis. The amount of weight loss achieved with combination therapy is of a greater magnitude than what could be achieved with either agent alone. Adverse events that occur with the combination therapy are in line with the known side effect profiles of the constituent drugs; teratogenicity, a slight increase in heart rate, psychiatric and cognitive adverse effects, and metabolic acidosis are concerns.

Short-term topiramate treatment does not improve insulin sensitivity or secretion in obese insulin-resistant women

OBJECTIVE

Long-term treatment with topiramate reduces body weight and improves insulin sensitivity in obese humans. Our aim was to evaluate the effect of topiramate treatment for 4 weeks on insulin sensitivity and secretion, independent of weight loss.

DESIGN

Randomized, double-blind, crossover, placebo-controlled study.

METHODS

Thirteen obese (BMI 36.6 ± 1.3 kg/m(2) (mean ± s.e.m.)), insulin-resistant (homeostasis model of assessment-insulin resistance 2.0 ± 0.2) women received topiramate (T, maximum dose of 75 mg) and placebo (P) for 4 weeks, separated by a 4-week washout period. Insulin sensitivity and β-cell function were assessed using a two-step hyperinsulinemic euglycemic clamp with stable isotopes and a hyperglycemic clamp.

RESULTS

Hepatic and peripheral insulin sensitivities were not affected by topiramate treatment (glucose disposal rate (step 1 (insulin infusion rate 10 MU/M(2) per min) T: 17.5 ± 0.8 vs P: 18.5 ± 1.0 μmol/kg(LBM) per min, t=1.016, P=0.33; step 2 (insulin infusion rate 40 mU/m(2) per min) T: 27.9 ± 3.2 vs P: 28.8 ± 1.9 μmol/kg(LBM) per min, t=0.418, P=0.68)). Subjects lost a small amount of weight during the topiramate period (T: -1.0 ± 0.2 vs P: -0.1 ± 0.2 kg, t=2842, P=0.15). There were no changes in body fat mass, blood pressure, and fasting glucose. β-Cell function was not affected by topiramate as evidenced by an unaltered area under the curve of early (0-10 min; T: 1929.6 ± 265.7 vs P: 2024.7 ± 333.6 pmol/l, t=-0.357, P=0.73) and late (80-120 min; T: 28,017.7 ± 5029.9 vs P: 31,567.7 ± 5376.2 pmol/l, t=-1.481, P=0.16) phase insulin levels during hyperglycemia. The use of topiramate was associated with significant side effects such as paresthesia, nausea, dizziness, and concentration problems.

CONCLUSIONS

Low-dose topiramate treatment for 4 weeks, relative to placebo, had no significant effect on insulin sensitivity in overweight/obese adult females without established diabetes.

A randomized, double-blind, placebo-controlled study of an oral, extended-release formulation of phentermine/topiramate for the treatment of obstructive sleep apnea in obese adults

STUDY OBJECTIVES

To evaluate safety and efficacy of phentermine 15 mg plus extended-release topiramate 92 mg for treatment of moderate to severe obstructive sleep apnea (OSA) in obese adults.

DESIGN

This phase 2, randomized, double-blind, placebo-controlled study included 2-week screening and 28-week treatment periods. Overnight polysomnography was performed at baseline, Week 8, and Week 28.

SETTING

Single-center study conducted from August 2008 to September 2009.

PARTICIPANTS

Forty-five subjects with moderate to severe OSA not receiving positive airway pressure (PAP) treatment with body mass index of 30-40 kg/m(2).

INTERVENTIONS

Subjects were randomized to receive placebo (n = 23) or phentermine 15 mg plus extended-release topiramate 92 mg (n = 22). Both groups received lifestyle-modification counseling.

MEASUREMENTS AND RESULTS

Primary endpoint, change in apnea-hypopnea index (AHI), significantly favored phentermine 15 mg plus extended-release topiramate 92 mg (-31.5 events/h, 95% CI: -40.0, -22.9) over placebo (-16.6 events/h, 95% CI: -25.0, -8.2) at Week 28 (P =0.0084). At Week 28, there was a 10.2% (95% CI: -12.7, -7.6; 10.8 kg, 95% CI: -13.5, -8.0) mean decrease in weight in the phentermine 15 mg plus extended-release topiramate 92 mg group compared with 4.3% (95% CI: -6.6, -2.0; 4.7 kg, 95% CI: -7.2, -2.2) in the placebo group (P = 0.0006) and a positive, significant (P = 0.0003) correlation between percent change in weight and change in AHI. Significant improvements in overnight oxygen saturation and reduction in blood pressure compared with placebo were observed. Phentermine 15 mg plus extended-release topiramate 92 mg was well tolerated with low adverse event rates.

CONCLUSIONS

Phentermine 15 mg plus extended-release topiramate 92 mg induced significant weight reductions and concomitant improvements in OSA and related symptoms vs placebo. This suggests weight loss mediated by phentermine 15 mg plus extended-release topiramate 92 mg may be useful in treatment of moderate to severe OSA in obese subjects unable or unwilling to comply with PAP treatment.

The potential role of glutamate in the current diabetes epidemic

In the present article, we propose the perspective that abnormal glutamate homeostasis might contribute to diabetes pathogenesis. Previous reports and our recent data indicate that chronically high extracellular glutamate levels exert direct and indirect effects that might participate in the progressive loss of β-cells occurring in both T1D and T2D. In addition, abnormal glutamate homeostasis may impact all the three accelerators of the "accelerator hypothesis" and could partially explain the rising frequency of T1D and T2D.

Long-lasting remission of type 1 diabetes following treatment with topiramate for generalized seizures

We report a case of unusually long-lasting remission of type 1 diabetes (T1D). The patient, a Caucasian man, at the age of 43 years developed a ketotic diabetes, classified as type 1 based on clinical presentation and positivity for islet autoantibodies. Shortly after diabetes onset, oral topiramate was added to preexisting valproic acid for generalized seizures and maintained thereafter. Initial intensive insulin treatment was rapidly reduced to low doses (3 Units/day) maintained for a long time and then discontinued at month 55; fasting glucose and glycosylated hemoglobin were basically normalized at 58 months. An oral glucose tolerance test performed at month 53 showed an impaired fasting glucose (6.0 mmol/l) and a value slightly above the threshold for the diagnosis of diabetes at 2 h (11.2 mmol/l). We hypothesize that this unusually prolonged preservation of β-cell function might be ascribed to the concomitant therapy with topiramate, an antiepileptic agent with demonstrated efficacy as antidiabetic in type 2 diabetes (T2D). Topiramate should be further investigated as candidate agent for the preservation of β-cell function also in T1D.

Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP)

A 56-week randomized controlled trial was conducted to evaluate safety and efficacy of a controlled-release combination of phentermine and topiramate (PHEN/TPM CR) for weight loss (WL) and metabolic improvements. Men and women with class II and III obesity (BMI ≥ 35 kg/m(2)) were randomized to placebo, PHEN/TPM CR 3.75/23 mg, or PHEN/TPM CR 15/92 mg, added to a reduced-energy diet. Primary end points were percent WL and proportions of patients achieving 5% WL. Secondary end points included waist circumference (WC), systolic and diastolic blood pressure (BP), fasting glucose, and lipid measures. In the primary analysis (randomized patients with at least one postbaseline weight measurement who took at least one dose of assigned drug or placebo), patients in the placebo, 3.75/23, and 15/92 groups lost 1.6%, 5.1%, and 10.9% of baseline body weight (BW), respectively, at 56 weeks (P < 0.0001). In categorical analysis, 17.3% of placebo patients, 44.9% of 3.75/23 patients, and 66.7% of 15/92 patients, lost at least 5% of baseline BW at 56 weeks (P < 0.0001). The 15/92 group had significantly greater changes relative to placebo for WC, systolic and diastolic BP, fasting glucose, triglycerides, total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL). The most common adverse events were paresthesia, dry mouth, constipation, dysgeusia, and insomnia. Dropout rate from the study was 47.1% for placebo patients, 39.0% for 3.75/23 patients, and 33.6% of 15/92 patients. PHEN/TPM CR demonstrated dose-dependent effects on weight and metabolic variables in the direction expected to be beneficial with no evidence of serious adverse events induced by treatment.

Two-year sustained weight loss and metabolic benefits with controlled-release phentermine/topiramate in obese and overweight adults (SEQUEL): a randomized, placebo-controlled, phase 3 extension study

BACKGROUND

Obesity is a serious chronic disease. Controlled-release phentermine/topiramate (PHEN/TPM CR), as an adjunct to lifestyle modification, has previously shown significant weight loss compared with placebo in a 56-wk study in overweight and obese subjects with ≥2 weight-related comorbidities.

OBJECTIVE

This study evaluated the long-term efficacy and safety of PHEN/TPM CR in overweight and obese subjects with cardiometabolic disease.

DESIGN

This was a placebo-controlled, double-blind, 52-wk extension study; volunteers at selected sites continued with original randomly assigned treatment [placebo, 7.5 mg phentermine/46 mg controlled-release topiramate (7.5/46), or 15 mg phentermine/92 mg controlled-release topiramate (15/92)] to complete a total of 108 wk. All subjects participated in a lifestyle-modification program.

RESULTS

Of 866 eligible subjects, 676 (78%) elected to continue in the extension. Overall, 84.0% of subjects completed the study, with similar completion rates between treatment groups. At week 108, PHEN/TPM CR was associated with significant, sustained weight loss (intent-to-treat with last observation carried forward; P < 0.0001 compared with placebo); least-squares mean percentage changes from baseline in body weight were -1.8%, -9.3%, and -10.5% for placebo, 7.5/46, and 15/92, respectively. Significantly more PHEN/TPM CR-treated subjects at each dose achieved ≥5%, ≥10%, ≥15%, and ≥20% weight loss compared with placebo (P < 0.001). PHEN/TPM CR improved cardiovascular and metabolic variables and decreased rates of incident diabetes in comparison with placebo. PHEN/TPM CR was well tolerated over 108 wk, with reduced rates of adverse events occurring between weeks 56 and 108 compared with rates between weeks 0 and 56.

CONCLUSION

PHEN/TPM CR in conjunction with lifestyle modification may provide a well-tolerated and effective option for the sustained treatment of obesity complicated by cardiometabolic disease. This trial was registered at clinicaltrials.gov as NCT00796367.

Weight-reducing side effects of the antiepileptic agents topiramate and zonisamide

Drug-induced weight alteration can be a serious side effect that applies to several therapeutic agents and must be referred to in the respective approved labeling texts. The side effect may become health threatening in case of significant weight change in either direction. Several antiepileptic drugs (AEDs) are associated with weight gain such as gabapentin, pregabalin, valproic acid, and vigabatrin and to some extent carbamazepine. Others are weight neutral such as lamotrigine, levetiracetam, and phenytoin or associated with slight weight loss as, e.g., felbamate. The focus of this chapter is on the two AEDs causing strong weight loss: topiramate and zonisamide. For both drugs, several molecular mechanisms of actions are published. We provide a review of these potential mechanisms, some of which are based on in vivo studies in animal models for obesity, and of clinical studies exploring these two drugs as single entities or in combinations with other agents.

Sympathetic nervous system in obesity-related hypertension: mechanisms and clinical implications

Obesity markedly increases the risk of hypertension and cardiovascular disease, which may be related to activation of the sympathetic nervous system (SNS). Sympathetic overactivity directly and indirectly contributes to blood pressure (BP) elevation in obesity, including stimulation of the renin-angiotensin-aldosterone system (RAAS). The adipocyte-derived peptide leptin suppresses appetite, increases thermogenesis, but also raises SNS activity and BP. Obese individuals exhibit hyperleptinemia but are resistant to its appetite-suppressing actions. Interestingly, animal models of obesity exhibit preserved sympathoexcitatory and pressor actions of leptin, despite resistance to its anorexic and metabolic actions, suggesting selective leptin resistance. Disturbance of intracellular signaling at specific hypothalamic neural networks appears to underlie selective leptin resistance. Delineation of these pathways should lead to novel approaches to treatment. In the meantime, treatment of obesity-hypertension has relied on antihypertensive drugs. Although sympathetic blockade is mechanistically attractive in obesity-hypertension, in practice its effects are disappointing because of adverse metabolic effects and inferior outcomes. On the basis of subgroup analyses of obese patients in large randomized clinical trials, drugs such as diuretics and RAAS blockers appear superior in preventing cardiovascular events in obesity--hypertension. An underused alternative approach to obesity-hypertension is induction of weight loss, which reduces circulating leptin and insulin, partially reverses resistance to these hormones, decreases sympathetic activation and improves BP and other risk factors. Though weight loss induced by lifestyle is often modest and transient, carefully selected pharmacological weight loss therapies can produce substantial and sustained antihypertensive effects additive to lifestyle interventions.

Medication Repurposing: New Uses for Old Drugs

Background:

Medication repurposing, the practice of using old drugs in new ways, is becoming more common. Old drugs that had previously fallen out of favor due to safety concerns, lack of efficacy, or development of more desirable therapeutic alternatives have been resurfacing in the literature and on pharmacy shelves. Developing new uses for old drugs may provide patients with access to helpful therapies but may also present challenges and risks.

Objective:

To explore the rationale for, and historical context of, the developing trend of recycling existing drugs for new, innovative uses, and to provide pharmacy practitioners with information about how to find clinical evidence regarding these new uses.

Data Synthesis:

The process of obtaining marketing approval for new drugs can take an average of over 10 years and exceed $1 billion. Repurposing old drugs (both approved and unapproved) for new uses requires considerably fewer resources since information about production needs, pharmacology, and pharmacokinetics is already known. Other advantages of using old drugs include faster availability for patient use and known safety concerns for the original indication. Disadvantages of new uses for old drugs may include lack of clinical evidence, unknown safety for the new clinical context, limited availability of information about new uses, and liability or legal concerns. Several methods of identifying potential new uses exist, including the observance of previously unknown desirable pharmacologic effects during clinical use, new knowledge of a mechanism of action leading to exploration of innovative therapeutic areas, or screening compound libraries for targeted clinical activity.

Conclusions:

There are many examples of recycling existing medications for new purposes. Pharmacy practitioners should be aware of this developing trend and know how to find information about utilizing old drugs in new ways.

Efficacy and safety of topiramate on weight loss: a meta-analysis of randomized controlled trials

Topiramate was associated with weight loss in clinical trials. We summarize the evidence on the efficacy and safety of topiramate in the treatment of overweight/obesity. The databases Medline, Embase, and Cochrane were searched. Randomized controlled studies with at least 16 weeks of duration that report the effect of topiramate on weight loss and adverse events were eligible for inclusion. Ten studies were included (3320 individuals). Patients treated with topiramate lost an average of 5.34 kg (95% confidence interval [95%CI]-6.12 to -4.56) of additional weight as compared with placebo. According to meta-regression analysis, treatment duration and dosage were associated with the efficacy of topiramate treatment. Evaluating trials using topiramate 96-200 mg day(-1) , the weight loss was higher in trials with >28 weeks of duration (-6.58 kg [95%CI -7.48 to -5.68]) than in trials with ≤28 weeks (-4.11 kg [95%CI -4.92 to -3.30]). Data of 6620 individuals were available for adverse events evaluation and those more frequently observed were paraesthesia, taste impairment and psychomotor disturbances. The odds ratio for adverse events leading to topiramate withdrawal was 1.94 (95%CI 1.64-2.29) compared with the control group. In conclusion, topiramate might be a useful adjunctive therapeutic tool in the treatment of obesity as long as proper warnings about side effects are considered.

Effects of low-dose, controlled-release, phentermine plus topiramate combination on weight and associated comorbidities in overweight and obese adults (CONQUER): a randomised, placebo-controlled, phase 3 trial

BACKGROUND

Obesity is associated with a reduction in life expectancy and an increase in mortality from cardiovascular diseases, cancer, and other causes. We therefore assessed the efficacy and safety of two doses of phentermine plus topiramate controlled-release combination as an adjunct to diet and lifestyle modification for weight loss and metabolic risk reduction in individuals who were overweight and obese, with two or more risk factors.

METHODS

In this 56-week phase 3 trial, we randomly assigned overweight or obese adults (aged 18-70 years), with a body-mass index of 27-45 kg/m(2) and two or more comorbidities (hypertension, dyslipidaemia, diabetes or prediabetes, or abdominal obesity) to placebo, once-daily phentermine 7·5 mg plus topiramate 46·0 mg, or once-daily phentermine 15·0 mg plus topiramate 92·0 mg in a 2:1:2 ratio in 93 centres in the USA. Drugs were administered orally. Patients were randomly assigned by use of a computer-generated algorithm that was implemented through an interactive voice response system, and were stratified by sex and diabetic status. Investigators, patients, and study sponsors were masked to treatment. Primary endpoints were the percentage change in bodyweight and the proportion of patients achieving at least 5% weight loss. Analysis was by intention to treat. This study is registered with Clinical Trials.gov, number NCT00553787.

FINDINGS

Of 2487 patients, 994 were assigned to placebo, 498 to phentermine 7·5 mg plus topiramate 46·0 mg, and 995 to phentermine 15·0 mg plus topiramate 92·0 mg; 979, 488, and 981 patients, respectively, were analysed. At 56 weeks, change in bodyweight was -1·4 kg (least-squares mean -1·2%, 95% CI -1·8 to -0·7), -8·1 kg (-7·8%, -8·5 to -7·1; p<0·0001), and -10·2 kg (-9·8%, -10·4 to -9·3; p<0·0001) in the patients assigned to placebo, phentermine 7·5 mg plus topiramate 46·0 mg, and phentermine 15·0 mg plus topiramate 92·0 mg, respectively. 204 (21%) patients achieved at least 5% weight loss with placebo, 303 (62%; odds ratio 6·3, 95% CI 4·9 to 8·0; p<0·0001) with phentermine 7·5 mg plus topiramate 46·0 mg, and 687 (70%; 9·0, 7·3 to 11·1; p<0·0001) with phentermine 15·0 mg plus topiramate 92·0 mg; for ≥10% weight loss, the corresponding numbers were 72 (7%), 182 (37%; 7·6, 5·6 to 10·2; p<0·0001), and 467 (48%; 11·7, 8·9 to 15·4; p<0·0001). The most common adverse events were dry mouth (24 [2%], 67 [13%], and 207 [21%] in the groups assigned to placebo, phentermine 7·5 mg plus topiramate 46·0 mg, and phentermine 15·0 mg plus topiramate 92·0 mg, respectively), paraesthesia (20 [2%], 68 [14%], and 204 [21%], respectively), constipation (59 [6%], 75 [15%], and 173 [17%], respectively), insomnia (47 [5%], 29 [6%], and 102 [10%], respectively), dizziness (31 [3%], 36 [7%], 99 [10%], respectively), and dysgeusia (11 [1%], 37 [7%], and 103 [10%], respectively). 38 (4%) patients assigned to placebo, 19 (4%) to phentermine 7·5 mg plus topiramate 46·0 mg, and 73 (7%) to phentermine 15·0 mg plus topiramate 92·0 mg had depression-related adverse events; and 28 (3%), 24 (5%), and 77 (8%), respectively, had anxiety-related adverse events.

INTERPRETATION

The combination of phentermine and topiramate, with office-based lifestyle interventions, might be a valuable treatment for obesity that can be provided by family doctors.

FUNDING

Vivus.

Management of type 2 diabetes: evolving strategies for the treatment of patients with type 2 diabetes

The prevalence of type 2 diabetes continues to increase at an alarming rate around the world, with even more people being affected by prediabetes. Although the pathogenesis and long-term complications of type 2 diabetes are fairly well known, its treatment has remained challenging, with only half of the patients achieving the recommended hemoglobin A(1c) target. This narrative review explores the pathogenetic rationale for the treatment of type 2 diabetes, with the view of fostering better understanding of the evolving treatment modalities. The diagnostic criteria including the role of hemoglobin A(1c) in the diagnosis of diabetes are discussed. Due attention is given to the different therapeutic maneuvers and their utility in the management of the diabetic patient. The evidence supporting the role of exercise, medical nutrition therapy, glucose monitoring, and antiobesity measures including pharmacotherapy and bariatric surgery is discussed. The controversial subject of optimum glycemic control in hospitalized and ambulatory patients is discussed in detail. An update of the available pharmacologic options for the management of type 2 diabetes is provided with particular emphasis on newer and emerging modalities. Special attention has been given to the initiation of insulin therapy in patients with type 2 diabetes, with explanation of the pathophysiologic basis for insulin therapy in the ambulatory diabetic patient. A review of the evidence supporting the efficacy of the different preventive measures is also provided.

Nephrolithiasis in topiramate users

Topiramate is a neuromodulatory agent increasingly prescribed for a number of neurological and non-neurological indications. Topiramate-treated patients are at risk for nephrolithiasis due to hypocitraturia and high urine pH. However, the prevalence of symptomatic stone disease in TPM users is generally perceived to be low. This study was undertaken to assess in topiramate-treated patients the prevalence of symptomatic nephrolithiasis (by history) and of asymptomatic nephrolithiasis by computed tomography (CT) scan. Topiramate users were identified from a database of patients with neurological disorders at a single university hospital. Among 75 topiramate-treated adult patients with a median daily dose of 300 mg and median treatment duration of 48 months, the prevalence of symptomatic nephrolithiasis was 10.7%. In a subset of topiramate-treated patients and no history of symptomatic stone disease, the prevalence of asymptomatic nephrolithiasis detected by CT scan was 20%. The prevalence of symptomatic nephrolithiasis with long-term topiramate use is higher than reported in short-term studies. Furthermore, clinical prevalence is underestimated due to asymptomatic nephrolithiasis.

Familial vulnerability to an unusual cognitive adverse effect of topiramate: Discussion of mechanisms

BACKGROUND

Some patients experience cognitive disturbances with topiramate.

CASE HISTORIES

A 19-year-old bipolar woman and her 46-year-old mother with paranoid personality disorder both used topiramate (25-50 mg/day) off-label for weight loss. Both women suffer from learning disorders, and both are excessively sensitive to the sedative adverse effects of psychotropic medications.

RESULTS

Within days of starting topiramate, the women began to exhibit troublesome word- and phrase-repetition and word substitution, both occurring only in their written expression. The symptoms were associated with mild sedation, persisted during two weeks of topiramate treatment, and remitted days after topiramate was withdrawn.

DISCUSSION

The presence of the learning disorders and the sensitivity to the sedative adverse effects of drugs may explain why cognitive adverse effects, known to occur with topiramate, developed at the low dose of 25-50 mg/day. The proclivity of topiramate to affect language functions and a possible familial vulnerability herein may explain why the women explained similar, language-specific symptoms. An investigation of topiramate-induced cognitive impairments in family members with epilepsy may throw light on the subject.

Topiramate in the treatment of substance-related disorders: a critical review of the literature

OBJECTIVE

To critically review the literature on topiramate in the treatment of substance-related disorders.

DATA SOURCES

A PubMed search of human studies published in English through January 2009 was conducted using the following search terms: topiramate and substance abuse, topiramate and substance dependence, topiramate and withdrawal, topiramate and alcohol, topiramate and nicotine, topiramate and cocaine, topiramate and opiates, and topiramate and benzodiazepines.

STUDY SELECTION

26 articles were identified and reviewed; these studies examined topiramate in disorders related to alcohol, nicotine, cocaine, methamphetamine, opioids, Ecstasy, and benzodiazepines.

DATA EXTRACTION

Study design, sample size, topiramate dose and duration, and study outcomes were reviewed.

DATA SYNTHESIS

There is compelling evidence for the efficacy of topiramate in the treatment of alcohol dependence. Two trials show trends for topiramate's superiority over oral naltrexone in alcohol dependence, while 1 trial suggests topiramate is inferior to disulfiram. Despite suggestive animal models, evidence for topiramate in treating alcohol withdrawal in humans is slim. Studies of topiramate in nicotine dependence show mixed results. Human laboratory studies that used acute topiramate dosing show that topiramate actually enhances the pleasurable effects of both nicotine and methamphetamine. Evidence for topiramate in the treatment of cocaine dependence is promising, but limited by small sample size. The data on opioids, benzodiazepines, and Ecstasy are sparse.

CONCLUSIONS

Topiramate is efficacious for the treatment of alcohol dependence, but side effects may limit widespread use. While topiramate's unique pharmacodynamic profile offers a promising theoretical rationale for use across multiple substance-related disorders, heterogeneity both across and within these disorders limits topiramate's broad applicability in treating substance-related disorders. Recommendations for future research include exploration of genetic variants for more targeted pharmacotherapies.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.

Adverse endocrine and metabolic effects of psychotropic drugs: selective clinical review

The article critically reviews selected, clinically significant, adverse endocrine and metabolic effects associated with psychotropic drug treatments, including hyperprolactinaemia, hyponatraemia, diabetes insipidus, hypothyroidism, hyperparathyroidism, sexual dysfunction and virilization, weight loss, weight gain and metabolic syndrome (type 2 diabetes mellitus, dyslipidaemia and hypertension). Such effects are prevalent and complex, but can be managed clinically when recognized. They encourage continued critical assessment of benefits versus risks of psychotropic drugs and underscore the importance of close coordination of psychiatric and general medical care to improve long-term health of psychiatric patients. Options for management of hyperprolactinaemia include lowering doses, switching to agents such as aripiprazole, clozapine or quetiapine, managing associated osteoporosis, carefully considering the use of dopamine receptor agonists and ruling out stress, oral contraceptive use and hypothyroidism as contributing factors. Disorders of water homeostasis may include syndrome of inappropriate antidiuretic hormone (SIADH), managed by water restriction or slow replacement by hypertonic saline along with drug discontinuation. Safe management of diabetes insipidus, commonly associated with lithium, involves switching mood stabilizer and consideration of potassium-sparing diuretics. Clinical hypothyroidism may be a more useful marker than absolute cut-offs of hormone values, and may be associated with quetiapine, antidepressant and lithium use, and managed by thyroxine replacement. Hyper-parathyroidism requires comprehensive medical evaluation for occult tumours. Hypocalcaemia, along with multiple other psychiatric and medical causes, may result in decreased bone density and require evaluation and management. Strategies for reducing sexual dysfunction with psychotropics remain largely unsatisfactory. Finally, management strategies for obesity and metabolic syndrome are reviewed in light of the recent expert guidelines, including risk assessment and treatments, such as monoamine transport inhibitors, anticonvulsants and cannabinoid receptor antagonists, as well as lifestyle changes.

Changes in metabolic syndrome parameters in patients with schizoaffective disorder who participated in a randomized, placebo-controlled trial of topiramate

This study evaluated changes in the metabolic syndrome (MetS) parameters among patients with schizoaffective disorder-bipolar type who had previously participated in a randomized, placebo-controlled study of topiramate (Chengappa et al., 2007). Topiramate (or placebo) was added to pre-existing mood-stabilizer and/or antipsychotic treatment. Nearly 41% of the 46 participants with fully available data met criteria for MetS at the pre-study baseline, and six (13%) additional subjects met criteria for MetS during the 16-week study. Several subjects (mostly topiramate treated) showed the hypothesized and expected loss in body weight and this correlated with improved glycosylated hemoglobin or systolic and diastolic blood pressure measurements or improvements in lipid levels, whereas a few patients had inconsistent results. Limitations of the study include the lack of targeted treatments for specific components of the metabolic syndrome, and no controls for exercise, diet or concomitant medications. Nevertheless, screening, monitoring and targeted treatment for the metabolic syndrome in psychiatric patients is increasingly becoming the standard of practice. Moreover and especially pertinent to the readership of this journal is that as the prevalence of overweight and MetS have increased worldwide, the World Health Organization has proposed lower cut-off thresholds for obesity in Asia. Furthermore, lower thresholds for waist circumference have also been recommended for Asians.

Combination therapy for obesity and metabolic disease

PURPOSE OF REVIEW

There is a growing interest in developing combination therapies for treatment and management of obesity and related metabolic diseases.

RECENT FINDINGS

Emerging data from recently completed and ongoing randomized clinical trials suggest that certain combination-drug therapies in development have greater efficacy than currently available single-drug therapies in terms of achieved weight loss and reduction in risk factors.

SUMMARY

Combination-drug therapy may have a role in the treatment of obesity and related diseases as well as for prevention of risk factors. As we await safety data from studies with larger samples, the demonstrated efficacy of some of the combination drug therapies in late-stage development appears to be robust and clinically meaningful.

Progress and controversies: treating obesity and insulin resistance in the context of hypertension

Improvements in hypertension treatment and control are challenged by the increasing incidence of metabolic risk factors for hypertension, in particular, obesity and insulin resistance. Such risk factors can increase the severity of hypertension and can interact via a multitude of hormonal and inflammatory pathways. Their presence may affect antihypertensive agent choice with regard to antihypertensive efficacy as well as potential synergistic or antagonistic effects on inflammatory status and progression to diabetes. Furthermore, an increasing number of pharmacologic options are available to promote weight loss and insulin sensitivity that may affect blood pressure directly and indirectly. This review considers the metabolic basis for the complex interactions of hypertension with obesity and insulin resistance, and it assesses the clinical evidence for an impact of weight loss and insulin-sensitizing treatment on blood pressure. Awareness of these pathophysiologic interrelations and their implications for treatment are likely to be of increasing importance for successful blood pressure management.

Topiramate and type 2 diabetes: an old wine in a new bottle

Topiramate, a marketed antiepileptic drug, has been used to treat seizures and allied neurological problems since 1999. Recently, a series of newer findings for the use of topiramate have cropped up, which include Type 2 diabetes and obesity. In a series of clinical studies, a subset of neurological patients with Type 2 diabetes mellitus (T2DM) serendipitously showed better glycaemic control when treated with topiramate. It has since been demonstrated that topiramate can act both as an insulin secretagogue and sensitiser in T2DM animal models. Pathogenesis of Type 2 diabetes involves both beta-cell dysfunction and insulin resistance. Therefore, an agent that has dual action (insulin secretagougue and sensitisation) is preferred for T2DM. Topiramate seems to act through multiple mechanisms to ameliorate diabetic symptoms, some of them unknown. Hence, it becomes imperative to discuss its probable modes of action. Topiramate raises new hope as an antidiabetic agent or a potential new chemotype with a better safety profile for the treatment of T2DM.

Treatment modalities of obesity: what fits whom?

The prevalence of obesity is increasing in both developed and developing countries, with rates reaching approximately 10-35% among adults in the Euro-American region. Obesity is associated with increased risks of cardiovascular diseases, type 2 diabetes, arthritis, and some type of cancers. Obesity significantly affects the quality of life and reduces the average life expectancy. The effective treatment of obesity should address both the medical and the social burden of this disease. Obesity needs to be treated within the health care system as any other complex disease, with empathy and without prejudice. Both health care providers and patients should know that the obesity treatment is a lifelong task. They should also set realistic goals before starting the treatment, whereas keeping in mind that even a modest weight loss of 5-15% significantly reduces obesity-related health risks. Essential treatment of obesity includes low-calorie low-fat diets, increased physical activity, and strategies contributing to the modification of lifestyle. Anti-obesity drugs facilitate weight loss and contribute to further amelioration of obesity-related health risks. A short-term weight loss, up to 6 months, is usually achieved easily. However, the long-term weight management is often associated with a lack of compliance, failures, and a high dropout rate. Regular physical activity, cognitive behavioral modification of lifestyle, and administration of anti-obesity drugs improve weight loss maintenance. Bariatric surgery is an effective strategy to treat severely obese patients. Bariatric surgery leads to a substantial improvement of comorbidities as well as to a reduction in overall mortality by 25-50% during the long-term follow-up. Obesity treatment should be individually tailored and the following factors should be taken into account: sex, the degree of obesity, individual health risks, psychobehavioral and metabolic characteristics, and the outcome of previous weight loss attempts. In the future, an evaluation of hormonal and genetic determinants of weight loss could also contribute to a better choice of individual therapy for a particular obese patient. A multilevel obesity management network of mutually collaborating facilities should be established to provide individually tailored treatment. Centers of excellence in obesity management represented by multidisciplinary teams should provide comprehensive programs for the treatment of obesity derived from evidence-based medicine.

Molecular pharmacodynamics, clinical therapeutics, and pharmacokinetics of topiramate

Topiramate (TPM; TOPAMAX) is a broad-spectrum antiepileptic drug (AED) that is approved in many world markets for preventing or reducing the frequency of epileptic seizures (as monotherapy or adjunctive therapy), and for the prophylaxis of migraine. TPM, a sulfamate derivative of the naturally occurring sugar D-fructose, possesses several pharmacodynamic properties that may contribute to its clinically useful attributes, and to its observed adverse effects. The sulfamate moiety is essential, but not sufficient, for its pharmacodynamic properties. In this review, we discuss the known pharmacodynamic and pharmacokinetic properties of TPM, as well as its various clinically beneficial and adverse effects.

[Pharmacotherapy of obesity]

Diet, exercise and behavioral therapy are the basics for every treatment of obesity. If lifestyle intervention does not result in a weight loss of 5% within 3 to 6 months, an additional pharmacotherapy can be considered. Treated patients should have a BMI >/=30 kg/m(2) or at least a BMI >/=27 kg/m(2) plus accompanying comorbidities, such as type 2 diabetes, dyslipidemia or hypertension. Current guidelines list orlistat, sibutramine and rimonabant as possible options for the pharmacotherapy of obesity. These compounds result in moderate weight reduction and improvement of cardiovascular risk profile. Especially the improvement of glucose metabolism can be considered as clinically relevant. Different side effects of the various compounds need to be considered before their use. Additional options for the pharmacotherapy of obesity are currently developed, their approval, however, is unlikely to happen within the next couple of years.

Increased propensity for calcium phosphate kidney stones with topiramate use

Topiramate (TPM) is a neuromodulatory agent that was initially approved as an antiepileptic drug and is increasingly used in the treatment of a number of neurological and metabolic disorders. Among its various pharmacological actions, TPM has been shown to inhibit the activity of specific carbonic anhydrase enzymes in the kidney. This action is associated with the development of metabolic acidosis, hypocitraturia, hypercalciuria and elevated urine pH, leading to an increased risk of kidney stone disease. Despite the cautionary note in the package insert of TPM, the extent of these complications has not been fully explored. Few prescribing physicians are aware of these complications, underscoring the need for improved surveillance. Because the drug is among the most frequently prescribed agents in the US, more controlled studies are required to determine the prevalence of kidney stone disease among TPM users, and the optimal approach to prevent and treat nephrolithiasis in these individuals.

A randomized, double-blind, placebo-controlled, multicenter study to assess the efficacy and safety of topiramate controlled release in the treatment of obese type 2 diabetic patients

OBJECTIVE

This is a randomized, placebo-controlled study of the weight-loss efficacy and safety of a controlled-release (CR) formulation of topiramate in overweight and obese patients with type 2 diabetes treated with diet and exercise alone or in combination with metformin.

RESEARCH DESIGN AND METHODS

Patients with type 2 diabetes, BMI > or =27 kg/m2, A1C >6.5 and <11.0%, treated with diet and exercise alone or in combination with metformin monotherapy were enrolled. Patients were randomized to placebo or topiramate CR titrated up to 175 mg/day. Treatment consisted of a 7-week titration phase followed by a 9-week maintenance phase.

RESULTS

A total of 111 subjects were randomized and analyzed. By the end of week 16, patients in the placebo and topiramate groups lost 2.5 and 6.0 kg, which represented 2.3 and 5.8%, respectively, of their baseline body weight (P < 0.001 vs. placebo). A1C improved from a baseline of 7.4% in the placebo and 7.6% in the topiramate groups to 7.1 and 6.7%, respectively, representing a 0.4 and 0.9% reduction from baseline, respectively (P < 0.001 vs. placebo). Topiramate also significantly reduced blood pressure and urinary albumin excretion. Adverse events were predominantly neuropsychiatric or central and peripheral nervous system related.

CONCLUSIONS

Topiramate CR treatment produced significant weight loss and meaningful improvements in A1C and blood pressure in obese patients with type 2 diabetes treated with diet and exercise or in combination with metformin. However, the central nervous system and psychiatric adverse event profile of topiramate CR makes it unsuitable for the treatment of obesity and diabetes.

The antiepileptic drug topiramate preserves metabolism-secretion coupling in insulin secreting cells chronically exposed to the fatty acid oleate

Topiramate (Topamax), primarily prescribed against epilepsy, was reported to reduce body weight and to ameliorate glycemic control in obese patients with diabetes. In rodent models of obesity and diabetes, topiramate treatment counteracts hyperglycemia and increases insulin levels upon glucose tolerance test. These observations suggest that topiramate might exert direct action on insulin secreting cells, in particular regarding obesity associated beta-cell dysfunction. In this study, INS-1E beta-cells were exposed for 3 days to the fatty acid oleate (0.4mM) and concomitantly treated with therapeutic concentrations of topiramate before measurements of insulin secretion and metabolic parameters. In healthy cells, topiramate had no acute or chronic effects on insulin release. Exposure of INS-1E cells to oleate for 3 days increased insulin release at basal 2.5mM glucose and blunted the response to stimulatory glucose concentration (15mM). Such lipotoxic effects were associated with impaired mitochondrial function, as evidenced by partial loss of resting mitochondrial membrane potential and reduced hyperpolarization in response to glucose. Oil-red-O staining and triglyceride measurements revealed lipid accumulation in oleate treated cells. Topiramate treatment counteracted oleate-induced lipid load and partially protected against mitochondrial membrane dysfunction. In particular, topiramate restored glucose stimulated insulin secretion, essentially by maintaining low insulin release at basal glucose. Topiramate increased expression of the nutrient sensor PPARalpha and of the mitochondrial fatty acid carrier CPT-1, correlating with enhancement of beta-oxidation rate. The data demonstrate that a drug originally used as mood stabilizer exerts a direct action on beta-cells, protecting against lipid-induced dysfunction.