Fatal pulmonary hypertension associated with short-term use of fenfluramine and phentermine

Treatment-Refractory Dravet Syndrome: Considerations for Novel Medications

Before 2018, there were no U.S. Food and Drug Administration-approved medications for managing seizures in Dravet syndrome (DS). Common agents used in the antiepileptic drug regimens of patients with DS included clobazam, valproic acid, topiramate, and levetiracetam, among others; however, these agents alone rarely provide adequate seizure control. Management of seizures in DS changed in recent years with the approval of cannabidiol and stiripentol in 2018 and fenfluramine in 2020. This continuing education article summarizes available efficacy and safety data involving cannabidiol, stiripentol, and fenfluramine and provides a practical review of dosing strategies, pharmacokinetics, and monitoring interventions relevant to their use.

Medical and Surgical Obesity Treatments and Atherosclerosis: Mechanisms beyond Typical Risk Factors

PURPOSE OF REVIEW

This study aims to discuss the mechanisms by which GLP-1 agonists and bariatric surgery improve cardiovascular outcomes in severely obese patients.

RECENT FINDINGS

Recent studies have demonstrated that both GLP-1 agonist use and bariatric surgery reduce adverse cardiovascular outcomes. Improvements in traditional atherosclerosis risk factors in association with weight loss likely contribute, but weight loss-independent mechanisms are also suggested to have roles. We review the clinical and preclinical evidence base for cardiovascular benefit of LP-1 agonists and bariatric surgery beyond traditional risk factors, including improvements in endothelial function, direct impacts on atherosclerotic plaques, and anti-inflammatory effects.

Sex, Gender, and Sex Hormones in Pulmonary Hypertension and Right Ventricular Failure

Pulmonary hypertension (PH) encompasses a syndrome of diseases that are characterized by elevated pulmonary artery pressure and pulmonary vascular remodeling and that frequently lead to right ventricular (RV) failure and death. Several types of PH exhibit sexually dimorphic features in disease penetrance, presentation, and progression. Most sexually dimorphic features in PH have been described in pulmonary arterial hypertension (PAH), a devastating and progressive pulmonary vasculopathy with a 3-year survival rate <60%. While patient registries show that women are more susceptible to development of PAH, female PAH patients display better RV function and increased survival compared to their male counterparts, a phenomenon referred to as the "estrogen paradox" or "estrogen puzzle" of PAH. Recent advances in the field have demonstrated that multiple sex hormones, receptors, and metabolites play a role in the estrogen puzzle and that the effects of hormone signaling may be time and compartment specific. While the underlying physiological mechanisms are complex, unraveling the estrogen puzzle may reveal novel therapeutic strategies to treat and reverse the effects of PAH/PH. In this article, we (i) review PH classification and pathophysiology; (ii) discuss sex/gender differences observed in patients and animal models; (iii) review sex hormone synthesis and metabolism; (iv) review in detail the scientific literature of sex hormone signaling in PAH/PH, particularly estrogen-, testosterone-, progesterone-, and dehydroepiandrosterone (DHEA)-mediated effects in the pulmonary vasculature and RV; (v) discuss hormone-independent variables contributing to sexually dimorphic disease presentation; and (vi) identify knowledge gaps and pathways forward. © 2020 American Physiological Society. Compr Physiol 10:125-170, 2020.

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.

Determining the Effects of Combined Liraglutide and Phentermine on Metabolic Parameters, Blood Pressure, and Heart Rate in Lean and Obese Male Mice

Liraglutide, a glucagon-like peptide 1 (GLP-1) receptor agonist, and phentermine, a psychostimulant structurally related to amphetamine, are drugs approved for the treatment of obesity and hyperphagia. There is significant interest in combination use of liraglutide and phentermine for weight loss; however, both drugs have been reported to induce systemic hemodynamic changes, and as such the therapeutic window for this drug combination needs to be determined. To understand their impact on metabolic and cardiovascular physiology, we tested the effects of these drugs alone and in combination for 21 days in lean and obese male mice. The combination of liraglutide and phentermine, at 100 μg/kg/day and 10 mg/kg/day, respectively, produced the largest reduction in body weight in both lean and diet-induced obese (DIO) mice, when compared with both vehicle and monotherapy-treated mice. In lean mice, combination treatment at the aforementioned doses significantly increased heart rate and reduced blood pressure, whereas in DIO mice, combination therapy induced a transient increase in heart rate and decreased blood pressure. These studies demonstrate that in obese mice, the combination of liraglutide and phentermine may reduce body weight but only induce modest improvements in cardiovascular functions. Conversely, in lean mice, the additional weight loss from combination therapy does not improve cardiovascular parameters.

Treatment Strategies for Dravet Syndrome

Dravet syndrome (DS) is a medically refractory epilepsy that onsets in the first year of life with prolonged seizures, often triggered by fever. Over time, patients develop other seizure types (myoclonic, atypical absences, drops), intellectual disability, crouch gait and other co-morbidities (sleep problems, autonomic dysfunction). Complete seizure control is generally not achievable with current therapies, and the goals of treatment are to balance reduction of seizure burden with adverse effects of therapies. Treatment of co-morbidities must also be addressed, as they have a significant impact on the quality of life of patients with DS. Seizures are typically worsened with sodium-channel agents. Accepted first-line agents include clobazam and valproic acid, although these rarely provide adequate seizure control. Benefit has also been noted with stiripentol, topiramate, levetiracetam, the ketogenic diet and vagal nerve stimulation. Several agents presently in development, specifically fenfluramine and cannabidiol, have shown efficacy in clinical trials. Status epilepticus is a recurring problem for patients with DS, particularly in their early childhood years. All patients should be prescribed a home rescue therapy (usually a benzodiazepine) but should also have a written seizure action plan that outlines when rescue should be given and further steps to take in the local hospital if the seizure persists despite home rescue therapy.

Management of Dyslipidemia in Patients with Hypertension, Diabetes, and Metabolic Syndrome

PURPOSE OF REVIEW

The purpose of this review is to discuss dyslipidemia in the various common clinical conditions including hypertension, diabetes mellitus, and metabolic syndrome and review the current therapeutic strategy in these settings.

RECENT FINDINGS

Dyslipidemias are common in patients with hypertension, diabetes mellitus, and metabolic syndrome. Epidemiologic studies have shown a strong correlation between serum lipid levels and risk of atherosclerotic cardiovascular disease. Multifactorial intervention strategies aimed at controlling lipids, blood pressure, and blood glucose simultaneously achieve maximal reductions in cardiovascular risk. Dyslipidemia and metabolic abnormalities are strongly associated with atherosclerosis and worse cardiovascular outcomes. While pharmacotherapy with statins has been proven to be beneficial for dyslipidemia, lifestyle modification emphasizing weight loss and regular exercise is an essential component of the interventional strategy. The common thread underlying atherosclerosis and metabolic abnormalities is endothelial dysfunction. Improved understanding of the role of endothelium in health and disease can potentially lead to novel therapies that may preempt development of atherosclerosis and its complications.

Drugs That May Cause or Exacerbate Heart Failure: A Scientific Statement From the American Heart Association

Heart failure is a common, costly, and debilitating syndrome that is associated with a highly complex drug regimen, a large number of comorbidities, and a large and often disparate number of healthcare providers. All of these factors conspire to increase the risk of heart failure exacerbation by direct myocardial toxicity, drug-drug interactions, or both. This scientific statement is designed to serve as a comprehensive and accessible source of drugs that may cause or exacerbate heart failure to assist healthcare providers in improving the quality of care for these patients.

Pharmacotherapy for the treatment of obesity

The recognition of the complex counter-regulatory hormonal, metabolic and neurochemical mechanisms that promote weight regain following weight loss and the conceptualisation of obesity as a chronic disease requiring long-term management has led to increasing focus on the role of adjunctive therapies for obesity, particularly pharmacotherapy. Currently available pharmacotherapy achieves a weight loss intermediate between that commonly attained by lifestyle intervention and bariatric surgery, however its accessibility, compared to bariatric surgery increases its appeal. Despite the poor history of obesity pharmacotherapy, novel agents that are in development appear to have several advantages over predecessors. They are generally more selective in their mechanism of action, thereby potentially minimising adverse sequelae and improving the risk-benefit ratio of pharmacotherapy. Another approach has been to use combined pharmacotherapy to better counteract the multiple counter-regulatory neuroendocrine mechanisms which promote weight regain, as well as allowing lower constituent doses of the combined monotherapy agents, which improves the safety and tolerability of these agents that are usually required long-term for chronic weight maintenance. This review will provide an overview of past, present and future pharmacotherapy for obesity. The efficacy and safety profile of currently available pharmacotherapy will be discussed in the setting of stringent regulatory review processes now in place given the fraught history of pharmacological interventions for obesity. Potential novel therapies that seek to better target the multiple complex counter-regulatory mechanisms promoting weight regain while improving the efficacy/safety profile, will also be examined.

Tolerability and safety of the new anti-obesity medications

Worldwide obesity prevalence has nearly doubled since 1980. Due to numerous co-morbidities, obesity represents a serious health and socioeconomic problem worldwide. Pharmacotherapy should be an integral part of comprehensive obesity management. Drug therapy can assist in weight loss and its maintenance in those individuals who do not achieve appropriate weight loss through lifestyle interventions alone. After the withdrawal of sibutramine from the market in 2010, orlistat, a lipase inhibitor, was the only remaining prescription drug approved for the long-term treatment of obesity. In 2012, phentermine/topiramate extended-release (PHEN/TPM ER) combination and lorcaserin were approved by the US FDA as novel medications for long-term weight management. Three major phase III trials conducted with each drug confirmed their efficacy in terms of weight loss/maintenance and improvement of cardiometabolic risks. No head-to-head studies between the two new anti-obesity drugs have been carried out. However, in the existing studies PHEN/TPM ER had a superior weight loss profile to lorcaserin but the incidence of adverse effects was lower with lorcaserin. Both drugs were well-tolerated, and adverse events were modest in intensity, dose dependent, rather rare, and tended to decrease with the duration of treatment. Major safety concerns regarding PHEN/TPM ER include elevations in resting pulse rate, teratogenicity, mild metabolic acidosis, and psychiatric and cognitive adverse events. Valvulopathy, cognitive impairment, psychiatric disorders, and hypoglycemia represent major safety concerns for lorcaserin. Although existing trials have not demonstrated any significant issues with PHEN/TPM ER-induced heart rate elevation and lorcaserin-induced valvulopathy, all safety concerns should be seriously taken into account in patients treated with either of these novel anti-obesity medications.

Management of obesity and cardiometabolic risk - role of phentermine/extended release topiramate

The US Food and Drug Administration (FDA) recently approved lorcaserin and the combination of phentermine and extended release topiramate (phentermine/topiramate ER) for the treatment of obesity in conjunction with a lifestyle intervention, expanding the therapeutic options for long-term obesity pharmacotherapy, which was previously limited to orlistat. Combination phentermine/topiramate ER is associated with greater weight loss compared to its constituent monotherapy, with a more favorable adverse effect profile. Phentermine/topiramate ER also appears to have beneficial effects on cardiometabolic risk, although longer-term cardiovascular safety data are required. While there are no head-to-head studies among the currently available obesity pharmacotherapy agents, phentermine/topiramate ER appears to have a superior weight loss profile. This review will discuss the epidemiology, natural history, and cardiometabolic risk associated with obesity, provide an overview on current obesity pharmacotherapy, and summarize the recent clinical efficacy and safety data underpinning the FDA's approval of both phentermine/topiramate ER and lorcaserin as pharmacotherapy for a long-term obesity intervention.

Validation of a population-based method to assess drug-induced alterations in the QT interval: a self-controlled crossover study

PURPOSE

The purpose of this study was to ascertain, in the context of an integrated health care delivery system, the association between a comprehensive list of drugs known to have potential QT liability and QT prolongation or shortening.

METHODS

By using a self-controlled crossover study with 59 467 subjects, we ascertained intra-individual change in log-linear regression-corrected QT (QTcreg ) during the period between 1995 and mid-2008 for 90 drugs while adjusting for age, gender, race/ethnicity, comorbid conditions, number of electrocardiograms (ECGs), and time between pre-ECG and post-ECG. The proportion of users of each drug-developing incident long QT was also estimated.

RESULTS

Two drugs (nicardipine and levalbuterol) had no statistically significant intra-individual QTcreg shortening effects, 10 drugs had no statistically significant prolonging effect, and 78 (87%) of the drugs had statistically significant intra-individual mean QTcreg lengthening effects, ranging from 7.6 ms for aripiprazole to 25.2 ms for amiodarone. Three drugs were associated with mean QTcreg prolongation of 20 ms or greater: amiodarone (antiarrhythmic), terfenadine (antihistaminic), and quinidine (antiarrhythmic); whereas 11 drugs were associated with mean QTcreg prolongation of 15 ms or greater but less than 20 ms: trimipramine (tricyclic antidepressant), clomipramine (tricyclic antidepressant), disopyramide (antiarrhythmic), chlorpromazine (antipsychotic), sotalol (beta blocker), itraconazole (antifungal), phenylpropanolamine (decongestant/anorectic), fenfluramine (appetite suppressant), midodrine (antihypotensive), digoxin (cardiac glycoside/antiarrhythmic), and procainamide (antiarrhythmic).

CONCLUSIONS

QT prolonging effects were common and varied in strength. Our results lend support to past Food and Drug Administration regulatory actions and support the role for ongoing surveillance of drug-induced QT prolongation.

Spontaneously remitted pulmonary arterial hypertension associated with the herbal medicine "bofutsushosan"

Although the link between pulmonary arterial hypertension (PAH) and exposure to certain drugs has already been identified, we herein present the first case of herbal medicine-associated PAH in which the patient demonstrated spontaneous remission. A 38-year-old woman took the herbal medicine "bofutsushosan" for two weeks then stopped taking it due to exertional dyspnea. However, her dyspnea continued, and right heart catheterization revealed a mean pulmonary arterial pressure of 41 mmHg with a normal wedge pressure. Several months after treatment with oxygen therapy, the patient's dyspnea disappeared, and her pulmonary arterial pressure normalized. Further studies focusing on susceptibility factors to drug-induced pulmonary arterial hypertension are needed.

Fenfluramine-induced gene dysregulation in human pulmonary artery smooth muscle and endothelial cells

Fenfluramine is prescribed either alone or in combination with phentermine as part of Fen-Phen, an anti-obesity medication. Fenfluramine was withdrawn from the US market in 1997 due to reports of heart valvular disease, pulmonary arterial hypertension, and cardiac fibrosis. Particularly, idiopathic pulmonary arterial hypertension (IPAH), previously referred to as primary pulmonary hypertension (PPH), was found to be associated with the use of Fen-Phen, fenfluramine, and fenfluramine derivatives. The underlying mechanism of fenfluramine-associated pulmonary hypertension is still largely unknown. We reasoned that investigating drug-induced gene dysregulation would enhance our understanding of the fenfluramine-associated pathogenic mechanism of IPAH. Whole-genome gene expression profiles in fenfluramine-treated human pulmonary artery smooth muscle (PASMC) and endothelial (PAEC) cells (isolated from normal subjects) were compared with baseline expression in untreated cells. Fenfluramine treatment caused dysregulation in a substantial number of genes involved in a variety of pathways and biological processes. In addition to several common pathways and biological processes such as "MAPK signaling pathway," "inflammation response," and "calcium signaling pathway" shared between both cell types, pathways and biological processes such as "blood circulation," "muscle system process," and "immune response" were enriched among the dysregulated genes in PASMC. Pathways and biological processes such as those related to cell cycle, however, were enriched among the dysregulated genes in PAEC, indicating that fenfluramine could affect unique pathways (or differentially) in different types of pulmonary artery cells. While awaiting validation in a larger cohort, these results strongly suggested that fenfluramine could induce significant dysregulation of genes in multiple biological processes and pathways critical for normal pulmonary vascular functions and structure. The transcriptional and posttranscriptional changes in these genes may, therefore, contribute to the pathogenesis of fenfluramine-associated IPAH.

Pulmonary hypertension associated with use of phentermine

Weight-control drugs (known as anorexigens) such as fenfluramine have been linked with pulmonary hypertension in previous reports. In our case, a 29 year old woman was admitted for shortness of breath and was diagnosed with pulmonary hypertension. Three months ago, she had been taking phentermine for five weeks. Other factors that might have contributed to the development of pulmonary hypertension were excluded. With treatment, her symptoms improved. This is the first case that can suggest a possible connection between phenermine single medication with pulmonary hypertension. Phentermine has been considered a relatively safe drug to treat obesity, and further investigation is needed to decide the safety and dosage of phentermine.

Plexiform lesions in the lungs of domestic fowl selected for susceptibility to pulmonary arterial hypertension: incidence and histology

Plexiform lesions develop in the pulmonary arteries of humans suffering from idiopathic pulmonary arterial hypertension (IPAH). Plexogenic arteriopathy rarely develops in existing animal models of IPAH. In this study, plexiform lesions developed in the lungs of rapidly growing meat-type chickens (broiler chickens) that had been genetically selected for susceptibility to IPAH. Plexiform lesions developed spontaneously in: 42% of females and 40% of males; 35% of right lungs, and 45% of left lungs; and, at 8, 12, 16, 20, 24, and 52 weeks of age the plexiform lesion incidences averaged 52%, 50%, 51%, 40%, 36%, and 22%, respectively. Plexiform lesions formed distal to branch points in muscular interparabronchial pulmonary arteries exhibiting intimal proliferation. Perivascular mononuclear cell infiltrates consistently surrounded the affected arteries. Proliferating intimal cells fully or partially occluded the arterial lumen adjacent to plexiform lesions. Broilers reared in clean stainless steel cages exhibited a 50% lesion incidence that did not differ from the 64% incidence in flock mates grown on dusty floor litter. Microparticles (30 μm diameter) were injected to determine if physical occlusion and focal inflammation within distal pulmonary arteries might initiate plexiform lesion development. Three months postinjection no plexiform lesions were observed in the vicinity of persisting microparticles. Broiler chickens selected for innate susceptibility to IPAH represent a new animal model for investigating the mechanisms responsible for spontaneous plexogenic arteriopathy.

Validated method for determination of mazindol in human plasma by liquid chromatography/tandem mass spectrometry

A simple liquid chromatography/tandem mass spectrometry (LC/MS/MS) method with electrospray ionization in positive ion multiple reaction monitoring mode was developed for the quantification of mazindol (an anorectic agent) in human plasma. Fluoxetine was adopted as an internal standard (IS), and sample preparation involved one-step liquid/liquid extraction using ethyl acetate. The transition monitored were m/z 285>44 for mazindol and m/z 310>44 for IS. Chromatographic separation was achieved on a Capcell Pak MGII C(18) column using an isocratic mobile phase, consisting of acetonitrile-20mM ammonium formate in water (50:50, v/v, adjusted to pH 3.5 with formic acid) at a flow-rate of 0.2mL/min. The retention times of mazindol and fluoxetine were 1.03min and 1.45min, respectively. The lower limit of quantitation (LLOQ) was 0.1ng/mL using 200microL of plasma, and no interferences were detected in chromatograms. The bench top stability of mazindol was evaluated in buffered and non-buffered plasma. The selectivity, linearity, precision, accuracy, recovery, and stability of the devised method were fully validated and absolute and relative matrix effects were evaluated. The described method provides a fast and sensitive analytical tool for determining mazindol levels in plasma, and was successfully applied to a pharmacokinetic study in 24 healthy human subjects after oral administration of 2mg tablet formulation of mazindol under fasting conditions.

Pulmonary Vascular Disease

The pulmonary vasculature is an anatomic compartment that is frequently overlooked in the histologic review of lung biopsy samples, other than those obtained specifically to assess pulmonary vascular disease.1 Though often of a nonspecific nature, the histologic pattern of vascular remodeling may at times suggest its underlying pathogenesis and provide clues to the cause of pulmonary hypertension.2 Disproportionately severe vascular pathology may further indicate alternate disease processes, such as congestive heart failure or thromboemboli, contributing to the patient’s overall respiratory condition.

Imported compounded diet pill use among Brazilian women immigrants in the United States

In Brazil, compounded diet pills that combine amphetamines, benzodiazepines, antidepressants, diuretics and laxatives are often prescribed. In 2006, the Food and Drug Administration banned their sale in the United States (US) citing substantial safety concerns. This study evaluates the prevalence of, and factors associated with, use of these pills among Brazilian immigrant women aged 18-50. Pill use was assessed at one clinic and two churches using an anonymous survey (n = 307). While living in the US, 18% of clinic respondents and 9% of church respondents reported using these diet pills. Nearly two thirds of pill users reported adverse effects. In multivariate logistic regression analysis, being unmarried, college educated, dissatisfied with current weight, and advised by a US physician to lose weight were associated with greater odds of imported diet pill use. To enhance care of Brazilian immigrants, US physicians should become familiar with the health consequences of imported diet pills from Brazil.

Cardiovascular safety of drugs not intended for cardiovascular use: need for a new conceptual basis for assessment and approval

Recently, several drugs for non-cardiovascular diseases have ceased marketing because of cardiovascular risk, highlighting the importance of evaluating the cardiovascular safety of new drugs even if not intended for cardiovascular diseases. Assessing and ensuring acceptable cardiovascular safety of non-cardiovascular drugs is difficult; nonetheless, governmental regulatory agencies are likely to change the requirements for drug safety information. This article explores our recommendations for rethinking current regulatory policies, emphasizing the need for mandatory post-marketing surveillance registries and highlighting the exposures necessary to subserve the need for greater assessment of safety issues.

Pulmonary arterial hypertension: evaluation and management

Pulmonary arterial hypertension (PAH), a rare disease involving the pulmonary vascular circuit, is defined as an elevation in pulmonary arterial pressures and is characterized by symptoms of dyspnea, chest pain, and syncope. If left untreated, the disease carries a high mortality rate, with the most common cause of death being decompensated right heart failure. Over the past 5 years, there have been significant advances in this field in regards to understanding the pathogenesis, diagnosis, and classification of PAH. The availability of newer drugs has resulted in a radical change in the management of this disease with significant improvement in both quality of life and mortality. Ongoing research promises to lead to a more comprehensive understanding of the genetics, etiology, and pathogenesis of pulmonary arterial hypertension, which may ultimately translate into more effective therapeutic options.

Diagnosis and management of pulmonary hypertension over the past 100 years

Pulmonary hypertension is a rare disease with a poor prognosis. It was first described in the late 19th century as a clinical-pathological syndrome characterised by obstruction of the small pulmonary arteries and right ventricular hypertrophy in patients presenting with severe dyspnoea and cyanosis. After the development of right heart catheterisation in the second half of the 20th century, it was found that many diseases could cause pulmonary hypertension, which is now recognised to be high blood pressure in the arteries that supply the lungs. In the 1960s, an epidemic of pulmonary hypertension caused by appetite suppressants initiated a systematic collection of information on pulmonary hypertension, leading to the first international classification of pulmonary hypertension. Increased understanding of the pathogenesis of the various forms of pulmonary hypertension has led to novel treatments and holds promise for the future.

Safety of drug therapies used for weight loss and treatment of obesity

Some of the medications used for weight loss in the management of obesity have been associated with unacceptable morbidity and mortality. Safety concerns have led to the withdrawal of aminorex, followed by the fenfluramines in 1997, and phenylpropanolamine (norephedrine) in 2000. Aminorex was associated with an increased prevalence of primary pulmonary hypertension (PPH), fenfluramines with an increased prevalence of PPH and valvulopathy, and phenylpropanolamine with an increased risk of haemorrhagic stroke. Several studies have investigated the safety of the fenfluramines, yet the benefit-risk profile has not been conclusively quantified. This is due to several deficiencies in the published studies, including a lack of data on the baseline prevalences of comorbid conditions in obese subjects, and potential confounders and biases in the study designs. Although several studies and systematic reviews support an increased risk of PPH and valvulopathy in patients who have taken fenfluramines, without knowledge of the background prevalence it is not possible to determine if the exposure preceded the outcome. The population at higher risk of these adverse effects includes those taking higher doses or with a longer duration of exposure to fenfluramines and those with pre-existing cardiac disease or a genetic predisposition. Patients exposed to fenfluramines continue to be monitored, with some follow-up studies indicating no overall worsening in valvulopathy over time. There are limited efficacy and safety data for amfepramone (diethylpropion) and phentermine and their approval for the management of obesity is limited to short-term use. Orlistat and sibutramine are the only currently approved medications for long-term management of obesity. Although the benefit-risk profiles of sibutramine and orlistat appear positive, sibutramine continues to be monitored because of long-term safety concerns. The safety and efficacy of currently approved drug therapies have not been evaluated in children and elderly patient populations and there is limited information in adolescents, whilst the long-term safety of current and potential new drug therapies in adults will require several years of postmarketing surveillance to fully elucidate their adverse effect profiles.

Management and therapeutic options in pediatric pulmonary hypertension

Idiopathic pulmonary arterial hypertension is a rare and potentially fatal condition. Without treatment, survival is only approximately 2.8 years from diagnosis. However, if the pulmonary hypertension is secondary to other causes, especially to congenital heart disease, it is possible to survive for 30 years or more without treatment. In recent years, remarkable progress has been made, risk factors have been identified and improved imaging techniques, including echocardiography, computer tomography and magnetic resonance imaging, are available. The condition can affect children at any age from fetal life through to adulthood. Patients can present to the respiratory pediatrician with unresponsive asthma, to the neurologist with faints or to the general pediatrician with failure to thrive. Over the last few years there have been significant developments in the available therapy for managing this complicated disease, which have improved the prognostic outlook, such as oral bosentan and sildenafil, intravenous epoprostenol and interventional catheterization with atrial septostomy. This article reviews the current knowledge about causation, investigation and treatment of children with pulmonary hypertension in the clinical setting.

Mediators and modulators of pulmonary arterial hypertension

Pulmonary hypertension (PH), defined as a mean pulmonary arterial (PA) pressure of >25 mmHg at rest or >30 mmHg during exercise, is characterized by a progressive and sustained increase in pulmonary vascular resistance that eventually leads to right ventricular failure. Clinically, PH may result from a variety of underlying diseases (Table 1 and Refs. 50, 113, 124). Pulmonary arterial hypertension (PAH) may be familial (FPAH) or sporadic (idiopathic, IPAH), formerly known as primary pulmonary hypertension, i.e., for which there is no demonstrable cause. More often, PAH is due to a variety of identifiable diseases including scleroderma and other collagen disorders, liver disease, human immunodeficiency virus, and the intake of appetite-suppressant drugs such as phentermine and fenfluramine (72). Other, more common, causes of PAH include left ventricular failure (perhaps the most common cause), valvular lesions, chronic pulmonary diseases, sleep-disordered breathing, and prolonged residence at high altitude. This classification, now widely accepted, was first proposed at a meeting in Evian, France, in 1998, and modified in Venice, Italy, in 2003 (124).

Phentermine and anaesthesia

We describe the case of a woman who had two penroperative hypertensive crises that may have been due to her use of phentermine, a little-known sympathomimetic anti-obesity medication. The currently available anti-obesity medications are discussed: phentermine, diethylpropion, and sibutramine; all of which are sympathomimetics possessing noradrenaline and serotonin reuptake inhibitor activity. These medications should be discontinued one week preoperatively and have potential interactions with tramadol and antidepressants. The drug orlistat inhibits gastrointestinal lipase and may lead to fat soluble vitamin (A, D, E, and K) deficiency, so consideration should be given to checking coagulation status preoperatively.

Design and rationale of the Utah obesity study. A study to assess morbidity following gastric bypass surgery

PURPOSE

This paper details the design and baseline characteristics of a study on the morbidity associated with Roux-en-Y gastric bypass surgery (GBP) in severely obese adults. This study is designed to assess the effectiveness of GBP in reducing morbidity and maintaining weight loss. A wide array of clinical tests and psycho-behavioral questionnaires are included as part of the study.

METHODS

Three groups (n=1156 severely obese) have been recruited for this study: cases who were approved for and participated in surgery (n=415), a control group of GBP seeking individuals who were denied surgery (n=420) and a control group that was randomly chosen from a population of severely obese participants who were not seeking GBP (n=321). Clinical measures include: a physician interview and detailed medical history, resting electro- and echocardiograms, a submaximal exercise treadmill test and electrocardiogram, pulmonary function, limited polysomnography, resting metabolic rate, anthropometrics, resting and exercise blood pressure, comprehensive blood chemistry and urinalysis and dietary, quality of life and physical activity questionnaires. Most participants (76%) were tested following an overnight stay in a clinical research center. Remaining participants underwent less extensive testing in an outpatient clinic.

RESULTS

Baseline characteristics of the 1156 participants are available for selected measures. Mean+/-S.D. for BMI was 46+/-7.5 kg/m(2) (range=33 to 92) and for age was 44+/-11.4 years (range=18 to 72). The prevalence of diabetes and hypertension was 19% and 35%, respectively. Of the participants who had an echocardiogram or polysomnogram, 92% had left-ventricular hypertrophy and 85% had mild to severe sleep apnea. The two control groups were similar to the surgical group. At approximately 24 months, all participants will have a second clinical examination. Statistical comparisons of changes in morbidity variables will be made between the surgical and control groups.

CONCLUSIONS

This study design facilitates assessment of risks and benefits of GBP to perform recommendations on whether or not to perform surgery on the severely obese patient. Baseline and 2-year exams provide valuable data for comparison to future long-term follow-up data that can be collected at 5 and 10 years.

Pulmonary arterial hypertension

Pulmonary arterial hypertension is a disease of the small pulmonary arteries characterized by vascular narrowing and increased pulmonary vascular resistance, which eventually leads to right ventricular failure. Vasoconstriction, vascular proliferation, remodeling of the pulmonary vessels, and thrombosis are all contributing factors to the increased vascular resistance seen in this disease. Pulmonary arterial hypertension develops as a sporadic disease (idiopathic), as an inherited disorder (familial), or in association with certain conditions (collagen vascular diseases, portal hypertension, human immunodeficiency virus infection, congenital systemic-to-pulmonary shunts, ingestion of drugs or dietary products, or persistent fetal circulation). The pathogenesis of pulmonary arterial hypertension is a complicated, multifactorial process. It seems doubtful that any one factor alone is sufficient to activate the necessary pathways leading to the development of this disease. Rather, clinically apparent pulmonary arterial hypertension most likely develops after a second insult occurs in an individual who is already susceptible owing to genetic factors, environmental exposures, or acquired disorders. Currently, there is no cure for pulmonary arterial hypertension but several novel therapeutic options are now available that can improve symptoms and increase survival.

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

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

Hair analysis for fenfluramine and norfenfluramine as biomarkers for N-nitrosofenfluramine ingestion

In this paper, a high performance liquid chromatographic method with fluorescence detection (HPLC-FL) for the determination of fenfluramine (Fen) and norfenfluramine (Norf) in human hair as biomarker metabolites of N-nitrosofenfluramine (N-Fen) is described. Washed and cut hair segments were extracted by ultrasonication for 1h at room temperature in methanol. The extract was evaporated and applied for derivatization with the fluorescent reagent 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl). An HPLC-FL analysis was performed using an ODS column with mobile phase composition of acetonitrile and water (65:35, v/v) and monitored at 430 nm (excitation 325 nm). The method was sensitive with detection limits of 36 and 16 pg/mg hair for Fen and Norf, respectively. The linearity was assessed in the range 0.036-144 ng/mg for Fen and 0.016-127 ng/mg for Norf with correlation coefficients larger than 0.999. The method was successfully used for the segmental determination of Fen and Norf in hair samples obtained from hospitalized patients diagnosed with hepatotoxicity and suspected to ingest N-Fen. Both Fen and Norf could be detected in these patients' hair samples in the ranges 43-1389 pg/mg for Fen and 18-680 pg/mg for Norf and the results showed that the patients might ingest N-Fen for a period of not less than 5 months. As well, the method was applied for the determination of Fen and Norf in rats that possess pigmented and non-pigmented hair after an intraperitoneal administration of Fen. Both compounds were determined in black as well as in white hair.

Classification and epidemiology of pulmonary hypertension

Pulmonary hypertension is a complex disease that can be idiopathic, familial, or associated with a wide range of disease processes. This article outlines the classification of primary pulmonary hypertension and discusses the various types of the disease.

Pulmonary hypertension as a result of drug therapy

Pulmonary hypertension, as a result of adverse drug reactions, must be considered as a rare occurrence. With good medicinal chemistry and screening of compounds before entry into man, it should be almost totally avoidable. Life and medicine are a continuing challenge as our exploration of the regions of unknown biology throw up new targets and new mechanisms and may catch us again as the anorectic (anorectic) drug caught our predecessors.

Effect of sibutramine on macronutrient selection in male and female rats

Sibutramine, a serotonin-noradrenaline reuptake inhibitor (SNRI), has been shown to be a safe and effective weight-loss drug. The purpose of the present study was to examine whether sibutramine has an effect on macronutrient selection in both female and male rats in addition to total food intake. Wistar rats of both sexes were divided into three groups, and each group was offered a different set of three sensorily contrasting macronutrient-specific diets, each set including carbohydrate-, protein-, and fat-rich diets. Sibutramine (10 mg/kg) was shown to consistently decrease carbohydrate and fat intake at all data points regardless of gender and diet. Intake of carbohydrate differed between male and female rats at 2 h post administration with 2.5 and 5 mg/kg of sibutramine. The effect of sibutramine on protein intake was diet- and gender-specific. All doses of sibutramine decreased total food intake regardless of gender and diet group beginning at 6 h post administration. In conclusion, sibutramine affected macronutrient selection and emphasis on dietary recommendations, as well as appropriate dosage according to gender should be considered during therapy.

Liquid chromatography studies on the pharmacokinetics of phentermine and fenfluramine in brain and blood microdialysates after intraperitoneal administration to rats

A highly sensitive and simple HPLC method with fluorescence detection for the determination of phentermine (Phen), fenfluramine (Fen) and norfenfluramine (Norf, the active metabolite of Fen) in rat brain and blood microdialysates has been developed. The brain and blood microdialysates were directly subjected to derivatization with 4-(4,5-diphenyl-1H-imidazol-2-yl) benzoyl chloride (DIB-Cl) in the presence of carbonate buffer (0.1 M, pH 9.0) at room temperature. The chromatographic conditions consisted of an ODS column and mobile phase composition of acetonitrile and water (65:35, v/v) with flow rate set at 1.0 ml/min. The detection was performed at excitation and emission wavelengths of 325 and 430 nm, respectively. Under these conditions, the DIB-derivatives of Phen, Fen and Norf were well separated and showed good linearities in the studied ranges (5-2000 nM for Phen and 10-2000 nM for Norf and Fen) with correlation coefficients greater than 0.999. The obtained detection limits were less than 23 fmol on column (for the three compounds) in both brain and blood microdialysates at a signal-to-noise ratio of 3 (S/N=3). The intra- and the inter-assay precisions were lower than 10%. The method coupled with microdialysis was applied for a pharmacokinetic drug-drug interaction study of Phen and Fen following individual and combined intraperitoneal administration to rats. In addition, since the role of protein binding in drug interactions can be quite involved, the method was applied for the determination of total and free Phen and Fen in rat plasma and ultrafiltrate, respectively. The results showed that Fen and/or Norf significantly altered the pharmacokinetic parameters of Phen in both blood and brain but did not alter its protein binding. On the other hand, there was no significant difference in the pharmacokinetics of Fen when administered with Phen.

Primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a rare disorder characterised by raised pulmonary-artery pressure in the absence of secondary causes. Precapillary pulmonary arteries are affected by medial hypertrophy, intimal fibrosis, microthrombosis, and plexiform lesions. Most individuals present with dyspnoea or evidence of right heart failure. Echocardiography is the best non-invasive test to screen for suspected pulmonary hypertension. The discovery of mutations in the coding region of the gene for bone morphogenetic protein receptor 2 in patients with familial and sporadic PPH may help not only to elucidate pathogenesis but also to direct future treatment options. The pathogenesis is not completely understood, but recent investigations have revealed many possible candidate modifier genes. Without treatment, the disorder progresses in most cases to right heart failure and death. With current therapies such as epoprostenol, progression of disease is slowed, but not halted. Many promising new therapeutic options, including prostacyclin analogues, endothelin-1-receptor antagonists, and phosphodiesterase inhibitors, improve clinical function and haemodynamic measures and may prolong survival.

Dexfenfluramine protects against pulmonary hypertension in rats

Dexfenfluramine (Dex), an appetite suppressant and serotonin reuptake inhibitor, is associated with pulmonary vascular disease (PVD) in some patients. The variability might be related to undetermined genetic abnormalities interacting with factors such as gender, weight loss, and vascular injury. We, therefore, assessed the effect of Dex (5 mg. kg(-1). day(-1)) in female obese rats, designated JCR:LA-cp or cp/cp; in lean rats, designated (+/?); and in normal Sprague-Dawley (S-D) rats under control conditions or after endothelial injury induced by monocrotaline (60 mg/kg). Pulmonary arterial pressure, right ventricular hypertrophy, percent medial wall thickness of muscular arteries, and muscularization of peripheral arteries were assessed as indexes of PVD. Although Dex reduced weight gain in cp/cp and S-D rats (P < 0.05 for both), it did not cause PVD. Moreover, PVD in S-D rats after monocrotaline injection was paradoxically ameliorated by Dex (P < 0.05) despite induction of pulmonary artery elastase (P < 0.05), which we showed is critical in inducing experimental PVD. Thus it is possible that Dex is concomitantly offsetting the sequelae of elastase activity.

Janus face of vascular endothelial growth factor: the obligatory survival factor for lung vascular endothelium controls precapillary artery remodeling in severe pulmonary hypertension

Vascular endothelial growth factor (VEGF) plays a central role in the life and death of pulmonary vascular endothelial cells. Treatment of neonatal or adult rats with a VEGF receptor blocker destroys lung capillaries by inducing endothelial cell apoptosis and causes emphysema. Human lung tissue samples from patients with endstage emphysema have decreased levels of VEGF messenger RNA and protein and have decreased expression of kinase insert domain-containing receptor (VEGF receptor II). These decreases are associated with a high rate of alveolar septal cell apoptosis, indicating perhaps that decreased VEGF and kinase insert domain-containing receptor expression impairs endothelial cell survival in emphysematous lungs. Combination of VEGF receptor blockade with chronic hypoxia (3-wk exposure) results in obliteration of small precapillary pulmonary arteries by proliferating endothelial cells, severe pulmonary hypertension, and death caused by right-side heart failure. We propose that 1) VEGF receptor blockade causes endothelial cell apoptosis, 2) hypoxic vasoconstriction (shear stress) selects apoptosis-resistant endothelial cells that proliferate and obliterate the lumen, and 3) the vascular remodeling observed is relevant to the structural alterations that characterize severe pulmonary hypertension (including primary pulmonary hypertension) in humans. The endovascular cell growth in human disease and in our model exhibits some similarities with neoplastic cell growth. Chemotherapy strategies can now be employed in the animal model in an attempt to treat established vascular-obliterative lung disease.