Postmarketing surveillance study of the efficacy and safety of phentermine in patients with obesity

Effectiveness and safety of drugs for obesity

Recent publicity around the use of new antiobesity medications (AOMs) has focused the attention of patients and healthcare providers on the role of pharmacotherapy in the treatment of obesity. Newer drug treatments have shown greater efficacy and safety compared with older drug treatments, yet access to these drug treatments is limited by providers' discomfort in prescribing, bias, and stigma around obesity, as well as by the lack of insurance coverage. Now more than ever, healthcare providers must be able to discuss the risks and benefits of the full range of antiobesity medications available to patients, and to incorporate both guideline based advice and emerging real world clinical evidence into daily clinical practice. The tremendous variability in response to antiobesity medications means that clinicians need to use a flexible approach that takes advantage of specific features of the antiobesity medication selected to provide the best option for individual patients. Future research is needed on how best to use available drug treatments in real world practice settings, the potential role of combination therapies, and the cost effectiveness of antiobesity medications. Several new drug treatments are being evaluated in ongoing clinical trials, suggesting that the future for pharmacotherapy of obesity is bright.

Phentermine in the Modern Era of Obesity Pharmacotherapy: Does It Still Have a Role in Treatment?

PURPOSE OF REVIEW

This review provides an overview of the history, mechanism of action, and expected treatment effects of the anti-obesity medication (AOM), phentermine. It also includes a summary of recent research and practical guidance for prescribing clinicians.

RECENT FINDINGS

Recent research on phentermine is sparse and consists primarily of observational studies with methodologic limitations. These studies suggest that phentermine use is associated with clinically significant weight loss in adults and that the medication is generally well tolerated. Large-scale observational studies evaluating phentermine's safety have not identified an increased risk of cardiovascular events or elevations in blood pressure. There is no data to support the notion that phentermine is addictive. Although it remains the most commonly prescribed AOM in the USA, phentermine has little rigorous research to support its efficacy and safety in long-term treatment, which creates a dilemma with guideline-recommended chronic use of AOMs. While we await forthcoming conclusive data on this front, clinicians may consider using phentermine long-term in selected patients, if such prescribing is consistent with local regulatory statutes.

Biomaterial-Based Therapeutic Strategies for Obesity and Its Comorbidities

Obesity is a global public health issue that results in many health complications or comorbidities, including type 2 diabetes mellitus, cardiovascular disease, and fatty liver. Pharmacotherapy alone or combined with either lifestyle alteration or surgery represents the main modality to combat obesity and its complications. However, most anti-obesity drugs are limited by their bioavailability, target specificity, and potential toxic effects. Only a handful of drugs, including orlistat, liraglutide, and semaglutide, are currently approved for clinical obesity treatment. Thus, there is an urgent need for alternative treatment strategies. Based on the new revelation of the pathogenesis of obesity and the efforts toward the multi-disciplinary integration of materials, chemistry, biotechnology, and pharmacy, some emerging obesity treatment strategies are gradually entering the field of preclinical and clinical research. Herein, by analyzing the current situation and challenges of various new obesity treatment strategies such as small-molecule drugs, natural drugs, and biotechnology drugs, the advanced functions and prospects of biomaterials in obesity-targeted delivery, as well as their biological activities and applications in obesity treatment, are systematically summarized. Finally, based on the systematic analysis of biomaterial-based obesity therapeutic strategies, the future prospects and challenges in this field are proposed.

Weight Loss at First Month and Development of Tolerance as Possible Predictors of 30 mg Phentermine Efficacy at 6 Months

The efficacy of anti-obesity drugs usually does not consider the high degree of interindividual variability in responses to the drug which could affect the decision to withdraw the drug early due to ineffectiveness or to continue therapy according to specific expectations of success. The aim of this study was to analyze body weight loss in kilograms during the first month (1 mo-BWL_kg) of treatment with 30 mg phentermine and development of tolerance to phentermine, on its 6-month efficacy. One hundred sixty-six subjects with obesity were individually or jointly analyzed in the study. Subjects with 1 mo-BWL_kg of <1 kg, 1–3 kg, 3–5 kg, and ≥5 kg reached 6-month mean percentage body weight reductions (BWR%) of approximately 3%, 5%, 10%, and 15%, respectively. Development of late tolerance (4–6 months) to phentermine had a lower impact than early tolerance (2–3 months). Subjects with 1 mo-BWL_kg < 3 kg who developed early tolerance did not achieve relevant BWR% (≥5%) at month 6, while the rest of the subgroups achieved increasing and progressive BWR%, according to their 1 mo-BWL_kg range and time of onset of tolerance. The 1 mo-BWL_kg and development of tolerance to phentermine could be useful to predict the expected 6-month efficacy trends in obese patients treated with 30 mg phentermine.

Clinical outcomes associated with anti-obesity medications in real-world practice: A systematic literature review

Anti-obesity medications (AOMs) are efficacious and well tolerated in randomized controlled trials, but findings may not be generalizable to routine clinical practice. This systematic literature review aimed to identify real-world (RW) evidence for AOMs to treat adults ( ≥ 18 years) with obesity or overweight (BMI  ≥  27 kg/m² ). Searches conducted in MEDLINE, Embase, Health Technology Assessment (HTA) Database, National Health Service (NHS) Economic Evaluation Database, and Cochrane Central Register of Controlled Trials for studies of relevant FDA-approved AOMs yielded 41 publications. Weight loss (WL) was consistently observed, with 14% to 58.6% of patients achieving ≥ 5% WL on orlistat, phentermine/topiramate, naltrexone/bupropion, phentermine, or liraglutide in studies of 3-6 months' duration where this was measured. When cardiometabolic risk factors were assessed, AOMs reduced or had no impact on blood pressure, lipids, or glycemia. RW data on the impact of AOMs on existing obesity-related comorbidities and mortality were generally lacking. AOMs were associated with various adverse events, but these were of mild to moderate severity and no unexpected safety signals were reported. A pattern of poor adherence and persistence with AOMs was observed across studies. Overall, the review confirmed the effectiveness of AOMs in RW settings but demonstrated large gaps in the evidence base.

Randomized trial of a novel lifestyle intervention compared with the Diabetes Prevention Program for weight loss in adult dependents of military service members

BACKGROUND

Lifestyle interventions are the first-line treatment for obesity, but participant weight loss is typically low.

OBJECTIVES

We evaluated the efficacy of an alternative lifestyle intervention [Healthy Weight for Living (HWL)] compared with a modified Diabetes Prevention Program (m-DPP). HWL was based on a revised health behavior change model emphasizing hunger management and the development of healthy food preferences. m-DPP was a standard Diabetes Prevention Program implemented with counselor time matched to HWL. Participants were adult dependents of military personnel and had overweight or obesity.

METHODS

Participants were randomly assigned to HWL (n = 121) or m-DPP (n = 117), delivered primarily by group videoconference with additional midweek emails. The primary outcome was 12-mo weight change. Secondary outcomes included 6-mo changes in cardiometabolic risk factors and diet. Intention-to-treat (ITT) and complete case (CC) analyses were performed using linear mixed models.

RESULTS

Retention did not differ between groups (72% and 66% for HWL and m-DPP at 12 mo, respectively; P = 0.30). Mean ± SE adjusted 12-mo weight loss in the ITT cohort was 7.46 ± 0.85 kg for HWL and 7.32 ± 0.87 kg for m-DPP (P = 0.91); in the CC cohort, it was 7.83 ± 0.82 kg for HWL and 6.86 ± 0.88 kg for m-DPP (P = 0.43). Thirty-eight percent of HWL and 30% of m-DPP completers achieved ≥10% weight loss (P = 0.32). Improvements in systolic blood pressure, LDL cholesterol, triglycerides, fasting glucose, general health, sleep, and mood were similar across groups; improvements in diastolic blood pressure were greater in m-DPP. Adjusted group mean reductions in energy intake were not significantly different between groups, but HWL participants were more adherent to their dietary prescription for lower glycemic index and high fiber and protein (P = 0.05 to <0.001 for ITT).

CONCLUSIONS

HWL and m-DPP showed equivalent and clinically impactful mean weight loss with cardiometabolic benefits. These results identify an alternative approach for behavioral treatment of overweight and obesity.This trial was registered at clinicaltrials.gov as NCT02348853.

Anorectic interaction and safety of 5-hydroxytryptophan/carbidopa plus phentermine or diethylpropion in rat

Drug combinations are being studied as potential therapies to increase the efficacy or improve the safety profile of weight loss medications. This study was designed to determine the anorectic interaction and safety profile of 5-hydroxytryptophan (5-HTP)/carbidopa + diethylpropion and 5-HTP/carbidopa + phentermine combinations in rats. The anorectic effect of individual drugs or in combination was evaluated by the sweetened milk test. Isobologram and interaction index were employed to determine the anorectic interaction between 5-HTP/carbidopa and diethylpropion or phentermine. Plasma serotonin (5-HT) was measured by ELISA. Safety of repeated doses of both combinations in rats was evaluated using the tail sphygmomanometer, cardiac ultrasound, hematic biometry and blood chemistry. A single oral 5-HTP, diethylpropion or phentermine dose increased the anorectic effect, in a dose-dependent fashion, in 12 h-fasted rats. A dose of carbidopa at 30 mg/kg reduced the 5-HTP-induced plasmatic serotonin concentration and augmented the 5-HTP-induced anorectic effect. Isobologram and interaction index indicated a potentiation interaction between 5-HTP/30 mg/kg carbidopa + diethylpropion and 5-HTP/30 mg/kg carbidopa + phentermine. Chronic administration of experimental ED40 of 5-HTP/30 mg/kg carbidopa + phentermine, but not 5-HTP/30 mg/kg carbidopa + diethylpropion, increased the mitral valve leaflets area. Moreover, there were no other significant changes in cardiovascular, hematic or blood parameters. Both combinations induced around 20% body weight loss after 3 months of oral administration. Results suggest that 5-HTP/30 mg/kg carbidopa potentiates the anorectic effect of diethylpropion and phentermine with an acceptable safety profile, but further clinical studies are necessary to establish their therapeutic potential in the obesity treatment.

Effects of Gambisan in overweight adults and adults with obesity: A retrospective chart review

OBJECTIVE

A retrospective chart review was conducted to explore the effect of Gambisan, a granular extract of novel herbal medicine, for short-term (≤16 weeks) weight loss in adults who are overweight and those with obesity.

METHODS

Outpatients of Kyung Hee University Korean Medicine Hospital (Seoul, Korea) who took Gambisan and underwent bioelectric impedance analysis were selected (Jan 2011 to Dec 2015); their electronic medical records and clinical charts were retrospectively reviewed. The effectiveness of Gambisan was primarily evaluated by comparing body weight (BW) at baseline and endpoint, using paired t tests; the safety of Gambisan was evaluated on the basis of adverse events (AEs) experienced by patients.

RESULTS

Two hundred five patients were included in this study. The study population exhibited a significant reduction in BW (73.69 ± 14.49 kg to 69.01 ± 13.20 kg, P < .001) as well as percentage body fat (37.38 ± 5.38% to 34.50 ± 5.83%, P < .001). Moreover, 111 (54.1%) patients achieved modest weight loss (≥5%), while 35 (17.1%) achieved ≥10% weight loss. Furthermore, Gambisan induced significant reduction of BW in all subgroups (body mass index, sex, prescribed duration, and dosage). Among 139 patients with available data, 79 (56.8%) reported loss-of-appetite. In addition, 120 (mostly mild) AEs were reported in 69 (49.6%) patients, and the most frequent AEs were nausea, palpitation, and insomnia.

DISCUSSION

Despite limitations in interpreting the results of this retrospective medical record review, Gambisan induced statistically and clinically meaningful weight loss with a tolerable level of AEs. Based on the findings of this review, further well-designed clinical trials are warranted.

Can we win the war on obesity with pharmacotherapy?

INTRODUCTION

Obesity is a major health concern for several countries. The United States (U.S.) has arguably led the world in the percentage of overweight and/or obese per capita for several decades. As a result, numerous FDA-approved pharmacotherapeutic options are available for the long-term treatment of obesity. Although most of these medications have been on the U.S. market for a few years and have demonstrated efficacy for long-term weight loss in clinical trials, the impact of these medications on obesity in the U.S. has yet to be realized. Areas covered: We will review and evaluate why pharmacotherapy for obesity has not produced a meaningful reduction in the number of overweight and obese adults in the U.S. Expert commentary: Several obstacles, such as adverse drug effects, poor insurance coverage, not treating obesity as a chronic disease, and availability of other weight loss alternatives, has resulted in poor performance of pharmacotherapy for obesity in the U.S. market.

Greater hunger and less restraint predict weight loss success with phentermine treatment

OBJECTIVE

Phentermine is thought to cause weight loss through a reduction in hunger. It was hypothesized that higher hunger ratings would predict greater weight loss with phentermine.

METHODS

This is an observational pilot study in which all subjects were treated with phentermine for 8 weeks and appetite and eating behaviors were measured at baseline and week 8. Outcomes were compared in subjects with ≥5% vs. <5% weight loss, and linear regression was used to identify predictors of percent weight loss.

RESULTS

Twenty-seven subjects (37 ± 4.5 years, 93.8 ± 12.1 kg, BMI 33.8 ± 3.1 kg m(-2) ) completed the study, with mean weight loss of -5.4 ± 3.3 kg (-5.7% ± 3.2%). Subjects with ≥5% weight loss had higher baseline pre-breakfast hunger (P = 0.017), desire to eat (P =0.003), and prospective food consumption (0.006) and lower baseline cognitive restraint (P = 0.01). In addition, higher baseline home prospective food consumption (P = 0.002) and lower baseline cognitive restraint (P < 0.001) were found to be predictors of weight loss.

CONCLUSIONS

These results suggest that individuals reporting greater hunger and less restraint are more likely to achieve significant weight loss with phentermine. This information can be used clinically to determine who might benefit most from phentermine treatment.