Drug Insight: appetite suppressants

The Use of Phentermine for Obesity in Psychiatric Patients With Antipsychotics

OBJECTIVE

Phentermine is a commonly used weight-loss agent in the United States, but there is a little information about the use of phentermine for patients with obesity taking antipsychotic medications.

METHODS

We gathered 57 patients with obesity taking antipsychotic medications whose phentermine treatment was simultaneous with or after any type of antipsychotic exposure and collected data of clinical information, initial/follow-up anthropometric variables, and adverse events (AEs) for the 6-month study period.

RESULTS

In total, the mean body weight reduction (BWR) was 4.45 (7.04) kg, and the mean BWR percent (BWR%) was 3.92% (6.96%) at 6 months. Based on the response to phentermine, the patients were classified into two groups: the responder (n=25; BWR% ≥5%) and nonresponder (n=32; BWR% <5%) groups. The responder group's mean BWR and BWR% were 10.13 (4.43) kg and 9.35% (4.09%), respectively, at 6 months. The responders had higher rates of anticonvulsant combination therapy (ACT; responder, 72.0% vs. non-responder, 43.8%; p=0.033) and a shorter total antipsychotic exposure duration (responder, 23.9 [16.9] months vs. non-responder, 37.2 [27.6] months; p= 0.039). After adjusting age, sex, and initial body weight, ACT maintained a significant association with phentermine response (odds ratio=3.840; 95% confidence interval: 1.082-13.630; p=0.037). In the final cohort, there was no report of adverse or new-onset psychotic symptoms, and the common AEs were sleep disturbances, dry mouth, and dizziness.

CONCLUSION

Overall, phentermine was effective and tolerable for patients with obesity taking antipsychotic medications, and ACT (predominantly topiramate) augmented the weight-loss effect of phentermine.

Targeting skeletal muscle mitochondrial health in obesity

Metabolic demands of skeletal muscle are substantial and are characterized normally as highly flexible and with a large dynamic range. Skeletal muscle composition (e.g., fiber type and mitochondrial content) and metabolism (e.g., capacity to switch between fatty acid and glucose substrates) are altered in obesity, with some changes proceeding and some following the development of the disease. Nonetheless, there are marked interindividual differences in skeletal muscle composition and metabolism in obesity, some of which have been associated with obesity risk and weight loss capacity. In this review, we discuss related molecular mechanisms and how current and novel treatment strategies may enhance weight loss capacity, particularly in diet-resistant obesity.

Phentermine: A Systematic Review for Plastic and Reconstructive Surgeons

PURPOSE

Phentermine is the most prescribed antiobesity drug in America, with 2.43 million prescriptions written in 2011. Case reports suggest there are anesthetic risks, such as refractory hypotension, involved with its perioperative use. Despite these risks and the frequency of phentermine use among plastic surgery patients, there are no published guidelines for the perioperative management of phentermine use in the plastic surgery literature. To address this patient safety issue, we performed a systematic review and provide management recommendations.

METHODS

A systematic review of the pharmacology of phentermine and the anesthetic risks involved with its perioperative use was undertaken using the search engines PubMed/MEDLINE, EMBASE, and Scopus.

RESULTS

A total of 251 citations were reviewed, yielding 4 articles that discussed perioperative phentermine use and complications with anesthesia. One was a review article, 2 were case reports, and 1 was a letter. Complications included hypotension, hypertension, hypoglycemia, hyperthermia, bradycardia, cardiac depression, and acute pulmonary edema.

CONCLUSIONS

The relationship between phentermine and anesthesia, if any, is unclear. Hypotension on induction of general anesthesia is the most reported complication of perioperative phentermine use. Specifically, phentermine-induced hypotension may be unresponsive to vasopressors that rely on catecholamine release, such as ephedrine. Therefore, the decision to perform surgery, especially elective surgery, in a patient taking phentermine should be made with caution. Because of the half-life of phentermine, we recommend discontinuing phentermine for at least 4 days prior to surgery. This differs from the classic 2-week discontinuation period recommended for "fen-phen." The patient should be made aware of the increased risk of surgery, and a skilled anesthesiologist should monitor intraoperative blood pressure and body temperature for signs of autonomic derailment.

The link between obesity and migraine in childhood: a systematic review

Obesity and headache are two highly prevalent diseases both in adults and children and they are associated with a strong personal and social impact. Many studies suggest that obesity is comorbid with headache in general, and migraine in particular and obesity seems to be a risk factor for migraine progression and for migraine frequency both in adults and in children. Research shows that there are multiple areas of overlap between migraine pathophysiology and the central and peripheral pathways regulating feeding: inflammatory mediators such as the calcitonin gene-related protein (CGRP), neurotransmitters such as serotonin, peptides such as orexin and adipocytokines such as adiponectin (ADP) and leptin could explain the common pathogenesis. In this paper we discussed the association between obesity and migraine through the analysis of the most recent studies in children and we reviewed data from literature in order to assess the association between obesity and headache and to clarify the possible common pathogenic mechanisms.

Evolution of pharmacological obesity treatments: focus on adverse side-effect profiles

Pharmacotherapy directed toward reducing body weight may provide benefits for both curbing obesity and lowering the risk of obesity-associated comorbidities; however, many weight loss medications have been withdrawn from the market because of serious adverse effects. Examples include pulmonary hypertension (aminorex), cardiovascular toxicity, e.g. flenfluramine-induced valvopathy, stroke [phenylpropanolamine (PPA)], excess non-fatal cardiovascular events (sibutramine), and neuro-psychiatric issues (rimonabant; approved in Europe, but not in the USA). This negative experience has helped mould the current drug development and approval process for new anti-obesity drugs. Differences between the US Food and Drug Administration (FDA) and the European Medicines Agency, however, in perceptions of risk-benefit considerations for individual drugs have resulted in discrepancies in approval and/or withdrawal of weight-reducing medications. Thus, two drugs recently approved by the FDA, i.e. lorcaserin and phentermine + topiramate extended release, are not available in Europe. In contrast, naltrexone sustained release (SR)/bupropion SR received FDA approval, and liraglutide 3.0 mg was recently approved in both the USA and Europe. Regulatory strategies adopted by the FDA to manage the potential for uncommon but potentially serious post-marketing toxicity include: (i) risk evaluation and mitigation strategy programmes; (ii) stipulating post-marketing safety trials; (iii) considering responder rates and limiting cumulative exposure by discontinuation if weight loss is not attained within a reasonable timeframe; and (iv) requiring large cardiovascular outcome trials before or after approval. We chronicle the adverse effects of anti-obesity pharmacotherapy and consider how the history of high-profile toxicity issues has shaped the current regulatory landscape for new and future weight-reducing drugs.

Phentermine-topiramate: First combination drug for obesity

Obesity is spreading globally at an alarming speed. The management of obesity is multifaceted and includes lifestyle modifications as the cornerstone. Until only orlistat was approved for long term use in obesity. The US Food and Drug Administration granted approval to a fixed dose mid 2012 combination of phentermine immediate release and topiramate extended release in 2012 for treatment of obese patients or overweight patients with comorbid conditions. The new drug has shown significant weight loss compared with placebo for a period up to 2 years.

New pharmacological treatments for the management of obesity

Obesity is quickly becoming the leading preventable cause of death in the USA. Over 60 obesity-related comorbidities exist which increase the complexity and cost of medical care in obese patients. Even a moderate weight loss of 5 % can reduce morbidity associated with these conditions. Lifestyle modification through caloric restriction and enhanced exercise and physical activity remain the first line treatment for obesity. The development of pharmacologic agents for the treatment of obesity has been challenged by both lack of efficacy and serious adverse side effects leading to their removal from market. Two new agents were recently approved by the US Food and Drug Administration to complement lifestyle modification in obese (BMI ≥30 kg/m(2)) and overweight patients (BMI ≥27 kg/m(2) and one obesity-related comorbidity). Lorcaserin is a novel serotonin 5-HT2C selective agonist which has been shown in three phase III studies to significantly reduce weight and cardiovascular risk factors such as diabetes. Phentermine/topiramate extended release (ER) is a novel combination of two agents which have individually been shown to significantly reduce weight. The combination agent phentermine/topiramate ER has been shown to reduce weight in overweight and obese subjects in a number of studies. This article reviews the pharmacology, clinical efficacy, and safety of these new agents compared to past and other presently available medications for the treatment of obesity.

Obesity and headache: Part II--potential mechanism and treatment considerations

Obesity and headache are both associated with a substantial personal and societal impact, and epidemiologic studies have consistently identified a positive association between obesity and headache in general, as well as obesity and migraine specifically (see part I). In the current manuscript, we will discuss the potential mechanisms for the migraine-obesity association, with a focus on the central and peripheral pathophysiological pathways which overlap between migraine and those modulating the drive to feed. We then discuss surgical, behavioral, and pharmacological treatment considerations for overweight and obese migraineurs as well as for those with idiopathic intracranial hypertension. We close by briefly discussing where future research may be headed in light of this data.

18F-fluorobenzyl triphenyl phosphonium: a noninvasive sensor of brown adipose tissue thermogenesis

Recent studies have proposed activation of brown adipose tissue (BAT) thermogenesis as a new strategy to combat obesity. Currently, there is no effective noninvasive imaging agent to directly detect unstimulated BAT and quantify the core mechanism of mitochondrial thermogenesis. We investigated an approach to detect BAT depots and monitor thermogenesis using the mitochondria-targeting voltage sensor radiolabeled fluorobenzyltriphenyl phosphonium (FBnTP).

METHODS

(18)F-FBnTP, (14)C-FBnTP, (18)F-FDG, and (99m)Tc-sestamibi uptake in BAT at room temperature (n = 8) and cold-treated (n = 8) Lewis rats was assayed. The effect of the cold condition on (18)F-FBnTP retention in BAT was assessed in 8 treated and 16 control rats. The effect of the noradrenergic inhibitor propranolol on (14)C-FBnTP response to cold stimulation was investigated in an additional 8 treated and 8 control mice.

RESULTS

At room temperature, (18)F-FBnTP accumulated in BAT to an extent similar to that in the heart, second only to the kidney and twice as much as (99m)Tc-sestamibi. Prior exposure to cold (4°C) for 4 h resulted in an 82% decrease of (14)C-FBnTP uptake and an 813% increase of (18)F-FDG uptake in BAT. (99m)Tc-sestamibi uptake was not affected by cold. Administration of (18)F-FBnTP at room temperature 60 min before 120 and 240 min of exposure to cold resulted in marked washout of the tracer from BAT. Propranolol significantly diminished the effect of cold on (14)C-FBnTP and (18)F-FDG uptake into BAT.

CONCLUSION

The intense uptake of (18)F-FBnTP into BAT at room temperature and the response to cold stimulation suggest the unique potential advantage of (18)F-FBnTP not only in detecting unstimulated BAT at high contrast but also in quantifying the mitochondrial thermogenic activity. (18)F-FBnTP PET may serve as a useful technique to assess BAT volume and function.

Phentermine and topiramate for the management of obesity: a review

Obesity is now a major public health concern worldwide with increasing prevalence and a growing list of comorbidities and complications. The morbidity, mortality and reduced productivity associated with obesity and its complications result in a major burden to health care costs. Obesity is a complex chronic medical syndrome often with multiple different etiologic factors in individual patients. The long term successful management of obesity remains particularly challenging and invariably requires a multifaceted approach including lifestyle and behavioral modification, increased physical activity, and adjunctive pharmacotherapy. Bariatric surgery remains a last resort though at present it has the best results for achieving sustained robust weight loss. Obesity pharmacotherapy has been very limited in its role for long term obesity management because of the past history of several failed agents as well as the fact that presently available agents are few, and generally utilized as monotherapy. The recent FDA approval of the fixed drug combination of phentermine and extended release topiramate (topiramate-ER) (trade name Qsymia™) marks the first FDA approved combination pharmacotherapeutic agent for obesity since the Phen-Fen combination of the 1990s. This review details the history and clinical trial basis for the use of both phentermine and topiramate in obesity therapeutics as well as the results of clinical trials of their combination for obesity treatment in humans. The initial clinical approval trials offer evidence that this fixed drug combination offers synergistic potential for effective, robust and sustained weight loss with mean weight loss of at least 10% of baseline achieved and sustained for up to 2 years in over 50% of subjects treated. It is anticipated that this agent will be the first in a new trend of multi-agent combination therapy for the chronic adjunctive management of obesity.

Weight loss, HbA1c reduction, and tolerability of cetilistat in a randomized, placebo-controlled phase 2 trial in obese diabetics: comparison with orlistat (Xenical)

The objective of this multicenter, randomized, double-blind study was to determine the efficacy and safety of cetilistat and orlistat relative to placebo in obese patients with type 2 diabetes, on metformin. Following a 2-week run-in, patients were randomized to placebo, cetilistat (40, 80, or 120 mg three times daily), or orlistat 120 mg t.i.d., for 12 weeks. The primary endpoint was absolute change in body weight from baseline. Secondary endpoints included other measures of obesity and glycemic control. Similar reductions in body weight were observed in patients receiving cetilistat 80 or 120 mg t.i.d. or 120 mg t.i.d. orlistat; these reductions were significant vs. placebo (3.85 kg, P = 0.01; 4.32 kg, P = 0.0002; 3.78 kg, P = 0.008). In the 40 mg t.i.d. and placebo groups, reductions were 2.94 kg, P = 0.958 and 2.86 kg, respectively. Statistically significant reductions in glycosylated hemoglobin (HbA(1c)) were noted. Cetilistat was well tolerated, and showed fewer discontinuations due to adverse events (AEs) than in the placebo and orlistat groups. Discontinuation in the orlistat group was significantly worse than in the 120 mg cetilistat and placebo groups and was entirely due to gastrointestinal (GI) AEs. Treatment with cetilistat 80 or 120 mg t.i.d., or with orlistat 120 mg t.i.d., significantly reduced body weight and improved glycemic control relative to placebo in obese diabetic patients. Cetilistat was well tolerated with the number of discontinuations due to AEs being similar to placebo.

Pharmacotherapy for obesity

Obesity is associated with increased risk of conditions such as hypertension, dyslipidaemia, diabetes mellitus, and obstructive sleep apnoea. Pharmacotherapy for obesity should be considered in combination with lifestyle changes in obese patients, or overweight patients with other conditions that put them at risk of developing heart disease. Sibutramine and orlistat are the only two anti-obesity medications approved for long-term use. Sibutramine is a serotonergic and adrenergic drug that reduces food intake. Orlistat is a gastrointestinal lipase inhibitor that interferes with fat absorption. However, it commonly causes flatulence and diarrhoea. Rimonabant is the first of a series of endocannabinoid receptor antagonists. It was approved by the Committee for Medicinal Products for Human Use of the European Medicines Agency (EMEA) as an adjunct to diet and exercise in treating obesity in 2006. However, despite the extensive clinical trial data, EMEA announced in 2008 that it has recommended suspension of rimonabant because of its psychiatric side effects. Studies evaluating the long-term safety and efficacy of anti-obesity agents are needed.

Migraine and obesity: epidemiology, mechanisms, and implications

Adipose tissue is a dynamic neuroendocrine organ that is involved in multiple physiological and pathological processes, and when excessive, results in obesity. Clinical and population-based data suggest that migraine and chronic daily headache are associated with obesity, as estimated by anthropometric indices. In addition, translational and basic science research shows multiple areas of overlap between migraine pathophysiology and the central and peripheral pathways regulating feeding. Specifically, neurotransmittors such as serotonin, peptides such as orexin, and adipocytokines such as adiponectin and leptin have been suggested to have roles in both feeding and migraine. In this article, we first review the definition and ascertainment of obesity. This is followed by a review of the clinical and population-based studies evaluating the associations between obesity and chronic daily headache and migraine. We then discuss the central and peripheral pathways involved in the regulation of feeding, where it overlaps with migraine pathophysiology, and where future research may be headed in light of these data.

Pharmacological and neurotoxicological actions mediated by bupropion and diethylpropion

The antiappetite agent diethylpropion (DEP), and the antidepressant and antismoking aid compound bupropion (BP), not only share the same structural motif but also present similar mechanisms of action in the CNS. For example, both drugs induce the release as well as inhibit the reuptake of neurotransmitters such as a dopamine (DA) and norepinephrine (NE). In general, they produce mild side effects, including reversible psychomotor alterations mostly in geriatric patients (by BP), or moderate changes in neurotransmitter contents linked to oxidative damage (by DEP). Therefore, attention must be paid during any therapeutic use of these agents. Regarding the interaction of BP with the DA transporter, residues S359, located in the middle of TM7, and A279, located close to the extracellular end of TM5, contribute to the binding and blockade of translocation mediated by BP, respectively. Additional mechanisms of action have also been determined for each compound. For example, BP is a noncompetitive antagonist (NCA) of several nicotinic acetylcholine receptors (AChRs). Based on this evidence, the dual antidepressant and antinicotinic activity of BP is currently considered to be mediated by its stimulatory action on DA and NE systems as well as its inhibitory action on AChRs. Considering the results obtained in the archetypical mouse muscle AChR, a sequential mechanism can be hypothesized to explain the inhibitory action of BP on neuronal AChRs: (1) BP first binds to AChRs in the resting state, decreasing the probability of ion channel opening, (2) the remnant fraction of open ion channels is subsequently decreased by accelerating the desensitization process, and finally (3) BP interacts with a binding domain located between the serine (position 9') and valine (position 13') rings that is shared with the NCA phencyclidine and other tricyclic antidepressants. The homologous location in the alpha3beta4 AChR is between the serine and valine/phenylalanine rings. This new evidence opens a window for further investigation using AChRs as targets for the action of safer antidepressants and novel antiaddictive compounds.