Appetite-suppressant drugs and the risk of primary pulmonary hypertension. International Primary Pulmonary Hypertension Study Group

Genetics and immunogenetic aspects of primary pulmonary hypertension

Primary pulmonary hypertension (PPH), also referred to as unexplained or idiopathic pulmonary hypertension, is the clinical term used to describe a condition in patients for which we can find no underlying cause. Patients with PPH not uncommonly also have evidence of immune dysregulation: autoimmune disorders, drug therapy, or HIV infections. We will review these associations and possible relevant abnormalities in immune regulation with regard to how they may play a role in the pathogenesis of PPH. Autoantibody-HLA correlations have been observed in several subsets of PPH patients. In addition, a familial form of PPH has been described and characterized with linkage to chromosome 2q31-q32. The identification of a specific gene for PPH and the subsequent understanding of its effects will help us identify the basic cause of PPH. Furthering our understanding regarding the role(s) and significance of immunogenetic as well as genetic aspects of the pathogenesis and pathophysiology of PPH should also lead to improved therapeutic modalities for PPH.

A role for potassium channels in smooth muscle cells and platelets in the etiology of primary pulmonary hypertension

Plasma serotonin levels are markedly elevated in patients with primary pulmonary hypertension (PPH) and platelet levels of serotonin are low. Furthermore, plasma serotonin levels remain elevated after bilateral lung transplantation, in the absence of any pulmonary hypertension. Dexfenfluramine can cause the anorexigen-induced form of PPH that is clinically and histologically indistinguishable from PPH. We find that dexfenfluramine releases serotonin from platelets and inhibits its reuptake. These observations suggest that serotonin might be involved in, or be a marker for, the mechanism responsible for both forms of PPH. Dexfenfluramine causes inhibition of voltage-sensitive potassium (Kv) channels, membrane depolarization, and calcium entry in pulmonary artery smooth muscle cells and vasoconstriction in isolated perfused rat lungs. We have recently found that dexfenfluramine also inhibits Kv channels in megakaryocytes, the stem cell for platelets. In smooth muscle cells, taken from the pulmonary arteries of PPH patients, Kv channels appear to be dysfunctional. The underlying defect in PPH is likely to be an abnormality of one or more Kv channels in both pulmonary artery smooth muscle cells and platelets. Relatively few patients exposed to dexfenfluramine develop PPH. The factors responsible for susceptibility might be a difference in expression of potassium channels and/or a decrease in the endogenous production of nitric oxide.

Primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a progressive disease characterised by raised pulmonary vascular resistance, which results in diminished right-heart function due to increased right ventricular afterload. PPH occurs most commonly in young and middle-aged women; mean survival from onset of symptoms is 2-3 years. The aetiology of PPH is unknown, although familial disease accounts for roughly 10% of cases, which suggests a genetic predisposition. Current theories on pathogenesis focus on abnormalities in interaction between endothelial and smooth-muscle cells. Endothelia-cell injury may result in an imbalance in endothelium-derived mediators, favouring vasoconstriction. Defects in ion-channel activity in smooth-muscle cells in the pulmonary artery may contribute to vasoconstriction and vascular proliferation. Diagnostic testing primarily excludes secondary causes. Catheterisation is necessary to assess haemodynamics and to evaluate vasoreactivity during acute drug challenge. Decrease in pulmonary vascular resistance in response to acute vasodilator challenge occurs in about 30% of patients, and predicts a good response to chronic therapy with oral calcium-channel blockers. For patients unresponsive during acute testing, continuous intravenous epoprostenol (prostacyclin, PGI2) improves haemodynamics and exercise tolerance, and prolongs survival in severe PPH (NYHA functional class III-IV). Thoracic transplantation is reserved for patients who fail medical therapy. We review the progress made in diagnosis and treatment of PPH over the past 20 years.

Appetite suppressant drugs as inhibitors of human cytochromes P450: in vitro inhibition of P450-2D6 by D- and L-fenfluramine, but not phentermine

The activity of D-fenfluramine, L-fenfluramine, and phentermine as inhibitors of five human cytochromes P450 was evaluated using human liver microsomes in vitro. All three compounds produced negligible inhibition of P450-1A2, -2C9, -2E1, and -3A. Phentermine also did not inhibit P450-2D6. However, D- and L-fenfluramine significantly inhibited P450-2D6 activity as measured by dextromethorphan O-demethylation, with mean 50% inhibitory concentrations (15.1 microM) within one order of magnitude of that for fluoxetine (2.7 microM). Findings from the in vitro assay are consistent with clinical studies showing significant inhibition of desipramine clearance by coadministration of fenfluramine.

Long-term intravenous prostaglandin (epoprostenol or iloprost) for treatment of severe pulmonary hypertension

OBJECTIVE

To investigate the relation between the severity of pulmonary hypertension and the outcome of medical treatment.

METHODS

98 patients with primary pulmonary hypertension--nine (6%) with systemic disease and pulmonary hypertension and 39 (27%) with thromboembolic pulmonary hypertension--received medical treatment and were followed between 1982 and 1995. They were given long term intravenous prostaglandin treatment (either epoprostenol (n = 61) or iloprost (n = 13)) or conventional treatment with oral anticoagulants (n = 24) with or without calcium channel blockers. Event-free survival was measured to death or transplant surgery, or pulmonary thromboendarterectomy.

RESULTS

Prognosis (hazard ratio) was affected by: New York Heart Association grade, 1.52 (95% confidence interval 1.11 to 2.09); mixed venous oxygen saturation (SvO2%), 0.97 (0.95 to 0.98); cardiac index, 0.72 (0.49 to 1.06); mean right atrial pressure, 1.04 (1.01 to 1.07); and pulmonary vascular resistance, 1.02 (1.00 to 1.04). The median event-free survival time of patients with SvO2 < 60% was 239 days (0 to 502) on conventional treatment (n = 22) and 585 days (300 to 870) on prostaglandin treatment (n = 42). No difference was seen in patients with SvO2 > or = 60% between conventional treatment and prostaglandin treatment, survival being 1275 days (732 to 1818; (n = 48)) and 986 days (541 to 1431; n = 30)), respectively. Capacity for pulmonary vasodilatation did not predict outcome of treatment.

CONCLUSIONS

Continuous intravenous prostaglandins were more effective than anticoagulants, with or without calcium channel blockers, in prolonging survival in patients with right heart failure. In these patients a capacity to vasodilate did not predict outcome from medical treatment.

The pulmonary hypertensive fawn-hooded rat has a normal serotonin transporter coding sequence

The coding sequence of the serotonin transporter gene was compared in two strains of rat-the Wistar and the fawn-hooded rat (FHR). The FHR has an inherited platelet storage-pool deficiency and a widespread impairment of serotonin storage. It is also susceptible to systemic and pulmonary hypertension. The FHR provides a model to study the genetics in human systemic and pulmonary hypertension. We measured platelet function in these two strains by measuring incorporation of radiolabeled serotonin into a platelet suspension and found significant differences in serotonin uptake and release. The coding sequence for the serotonin transporter in the FHR has yet to be reported. No differences were found in the predicted amino acid sequence between these two strains of rat, either in the platelet or the lung samples or when compared with the published sequence of the brown rat. We conclude that differences in the primary structure of the serotonin transporter gene do not account for the altered serotonin storage in the FHR strain.

The fen-phen finale: a study of weight loss and valvular heart disease

OBJECTIVE

To assess weight loss, as well as the prevalence of valvular heart disease, in 21 obese women who completed 2 years of treatment by fenfluramine and phentermine (fen-phen) in June 1997.

RESEARCH METHODS AND PROCEDURES

Patients were 21 of 22 women who had completed a 1-year, open-label trial of fen-phen combined with lifestyle modification. This study describes the results of a second year of treatment. The presence of valvular heart disease, defined as aortic regurgitation of mild or greater severity and/or mitral regurgitation of moderate or greater severity, was assessed using two-dimensional, color Doppler and pulsed- and continuous-wave Doppler examinations.

RESULTS

At 2 years, the 21 patients had a mean reduction in initial weight of 13.9 + 10.0%, which was significantly (p<0.001) smaller than their 1-year loss of 17.1 +/- 8.7%. Nine of 21 patients reported that they took fen-phen irregularly during the last 4 months of the study because of fears of developing health complications. These nine patients had a 2-year weight loss of 8.7 +/- 7.5%, compared with a significantly (p<0.04) larger loss of 17.6 +/- 10.5% for participants who reported taking medication regularly. Six of 20 (30%) patients met criteria for valvular heart disease. None of the six had signs or symptoms of this condition.

DISCUSSION

Fenfluramine was withdrawn from the market on September 15, 1997 because of concerns that it was associated with valvular heart disease. The present findings are discussed in terms of the potentially favorable long-term benefits of combining lifestyle modification with weight loss medications that are both safe and effective.

Pituitary-adrenal responses to combined oral D-fenfluramine and intravenous naloxone in humans

1. 1. Fenfluramine is an optically active 5-hydroxytryptamine (5-HT) releaser and re-uptake inhibitor. Increased brain 5-HT mediates appetite suppression, the D enantiomer being more active than L- or DL-fenfluramine. Fenfluramine also stimulates the hypothalamic-pituitary-adrenal (HPA) axis, leading to suggestions that this could act as a marker for its biological actions. However, the D enantiomer appears less active than a comparable DL racemate dose in animals, while effects of D-fenfluramine on the human HPA axis remain unproven. The aim of the present study was to clarify this. 2. Seven healthy human volunteers (three male, four female; 18-58 years) received 30 mg oral D-fenfluramine or placebo, followed by 125 micrograms/kg, i.v. naloxone or placebo, in randomized, double-blinded, placebo-controlled afternoon studies. We measured plasma adrenocorticotropic hormone (ACTH) and cortisol levels in samples taken at intervals throughout the study period. 3. In contrast to previous results with DL-fenfluramine, we found no dynamic responses to D-fenfluramine alone and no augmentation of responses to naloxone. 4. Central pathways to HPA axis activation are apparently not stimulated by D-fenfluramine at this dose in humans, in contrast with DL-fenfluramine, where the L enantiomer may be more selective for proposed corticotropin-releasing hormone-mediated, post-synaptic 5-HT2 or noradrenergic mechanisms. As previously reported, D-fenfluramine significantly blunted the circadian fall in basal plasma cortisol, providing in vivo evidence for serotonergic involvement in circadian regulation.

Beneficial effect of diazoxide in obese hyperinsulinemic adults

Hyperinsulinemia, insulin resistance, and increased adipose tissue are hallmarks of the obesity state in both humans and experimental animals. The role of hyperinsulinemia as a possible preceding event in the development of obesity has been proposed. We previously demonstrated that administration of diazoxide (DZ), an inhibitor of insulin secretion, to obese hyperinsulinemic Zucker rats resulted in less weight gain, enhanced insulin sensitivity, and improved glucose tolerance. Assuming that hyperinsulinemia plays a major role in the development of human obesity, then its reversal should have therapeutic potential. To test this hypothesis, we conducted a randomized placebo-controlled trial in 24 hyperinsulinemic adults [body mass index (BMI) > 30 kg/m2]. All subjects were placed on a low-calorie (1260 for females and 1570 for males) Optifast (Sandoz, Minneapolis, MN) diet. After an initial 1-week lead-in period, 12 subjects (mean +/- SE for age and BMI, 31 +/- 1 and 40 +/- 2, respectively) received DZ (2 mg/kg BW.day; maximum, 200 mg/day, divided into 3 doses) for 8 weeks; and 12 subjects (mean +/- SE for age an BMI, 28 +/- 1 and 43 +/- 1, respectively) received placebo. Compared with the placebo group, DZ subjects had greater weight loss (9.5 +/- 0.69% vs. 4.6 +/- 0.61%, P < 0.001), greater decrease in body fat (P < 0.01), greater increase in fat-free mass to body fat ratio (P < 0.01), and greater attenuation of acute insulin response to glucose (P < 0.01). However, there was no significant difference in insulin sensitivity and glucose effectiveness, as determined by the insulin-modified i.v. glucose tolerance test (Bergman's minimal model) and no significant difference in glycohemoglobin values.

CONCLUSION

8 weeks treatment with DZ had a significant antiobesity effect in hyperinsulinemic obese adults without inducing hyperglycemia.

Echocardiographic assessment of pulmonary hypertension in Gaucher's disease

BACKGROUND

Enzyme therapy has been shown to decrease the signs and symptoms of Gaucher's disease. A few patients, however, develop pulmonary hypertension on such treatment. We investigated the frequency of pulmonary hypertension in Gaucher's disease.

METHODS

We studied 134 adults with type 1 Gaucher's disease, including 73 patients on enzyme replacement, with echocardiography. We measured tricuspid incompetence (TI) with continuous-wave doppler. Pulmonary hypertension was indicated by a TI gradient of more than 30 mm Hg.

FINDINGS

Nine (7%) patients had pulmonary hypertension: all were treated and six had undergone splenectomy. Chest radiographs confirmed the presence of pulmonary hypertension in these patients as well as in most patients with TI gradients of 25-29 mm Hg.

INTERPRETATION

The confounding effects of disease severity and splenectomy in many treated patients precluded definitive conclusion of cause and effect. Nonetheless, we found an unexpectedly high rate of pulmonary hypertension and recommended routine echocardiographic monitoring of all treated and untreated patients with type 1 Gaucher's disease. We also suggest consideration of treatment withdrawal if the TI gradient progresses to more than 30 mm Hg.

Partitioning of pulmonary vascular resistance in primary pulmonary hypertension

OBJECTIVES

This study sought to determine the site of increased pulmonary vascular resistance (PVR) in primary pulmonary hypertension by standard bedside hemodynamic evaluation.

BACKGROUND

The measurement of pulmonary vascular pressures at several levels of flow (Q) allows the discrimination between active and passive, flow-dependent changes in mean pulmonary artery pressure (Ppa), and may detect the presence of an increased pulmonary vascular closing pressure. The determination of a capillary pressure (Pc') from the analysis of a Ppa decay curve after balloon occlusion allows the partitioning of PVR in an arterial and a (capillary + venous) segment. These approaches have not been reported in primary pulmonary hypertension.

METHODS

Ppa and Pc' were measured at baseline and after an increase in Q induced either by exercise or by an infusion of dobutamine, at a dosage up to 8 microg/kg body weight per min, in 11 patients with primary pulmonary hypertension. Reversibility of pulmonary hypertension was assessed by the inhalation of 20 ppm nitric oxide (NO), and, in 6 patients, by an infusion of prostacyclin.

RESULTS

At baseline, Ppa was 52+/-3 mm Hg (mean value+/-SE), Q 2.2+/-0.2 liters/min per m2, and Pc' 29+/-3 mm Hg. Dobutamine did not affect Pc' and allowed the calculation of an averaged extrapolated pressure intercept of Ppa/Q plots of 34 mm Hg. Inhaled NO had no effect. Prostacyclin decreased Pc' and PVR. Exercise increased Pc' to 40+/-3 mm Hg but did not affect PVR.

CONCLUSIONS

ns. These findings are compatible with a major increase of resistance and reactivity at the periphery of the pulmonary arterial tree.

The case for medical management of obesity: a call for increased physician involvement

The United States is in the midst of an escalating epidemic of obesity. Over one-third of the adult population in the United States is currently obese and the prevalence of obesity is growing rapidly. By any criteria, obesity represents a chronic disease which is associated with a wide range of comorbidities, including coronary heart disease (CHD), Type 2 diabetes, hypertension and dyslipidemias. The comorbidities of obesity are common, occurring in over 70% of individuals with a BMI of > or = 27. In addition to obesity itself, excessive accumulation of visceral abdominal fat and significant adult weight gain also represent health risks. Physicians have an important role to play in the treatment of obesity. Unfortunately, the medical community has not been involved actively enough to help stem the major epidemic of obesity occurring in the United States. This article puts forth a proposed model for the treatment of obesity in clinical practice, including obtaining the "vital signs" of obesity, recommending lifestyle measures, and instituting pharmacologic therapy when appropriate. By utilizing a chronic disease treatment model, physicians can join other health care professionals to effectively treat the chronic disease of obesity. Relatively modest weight loss, on the order of 5-10% of initial body weight can result in significant health improvements for many patients and represent an achievable goal for most obese patients.

Effect of dexfenfluramine treatment in rats exposed to acute and chronic hypoxia

The anorexiant dexfenfluramine, which inhibits 5-hydroxytryptamine (5-HT) uptake, has been associated with an increase in the relative risk of developing primary pulmonary hypertension. The aim of this study was to investigate in rats whether dexfenfluramine (1) alters the pulmonary vasomotor effects of 5-HT and (2) aggravates the development of pulmonary hypertension during exposure to various levels of chronic hypoxia. In isolated lungs from normoxic rats, dexfenfluramine up to 10(-4) M did not elicit any vasoactive effects, and neither did pretreatment with dexfenfluramine (10[-5] M in the perfusate) modify the vasoactive effects of 5-HT. In normoxic conscious rats, dexfenfluramine given intravenously potentiated the pulmonary pressor response to acute hypoxia (10% O2). In rats chronically treated with dexfenfluramine during a 2-wk exposure to 15% or 10% O2, plasma 5-HT concentrations were significantly increased compared with hypoxic controls, whereas no differences were found for pulmonary artery pressure, right ventricular hypertrophy, or pulmonary vessel muscularization. In contrast, a continuous 5-HT infusion providing a sustained increase in plasma 5-HT levels was associated with increased muscularization of distal pulmonary arteries in response to 10% O2. Simultaneous administration of dexfenfluramine prevented the effect of exogenous 5-HT on vascular remodeling. Our findings show that dexfenfluramine does not potentiate the development of pulmonary hypertension in rats exposed to chronic hypoxia, despite its effect on plasma 5-HT concentrations.

Aminorex, dexfenfluramine, and primary pulmonary hypertension

BACKGROUND

In the late 1960s, an epidemic of primary pulmonary hypertension (PPH) occurred in Europe shortly after the introduction of aminorex fumarate, a potent anorexigen. A recently published case-control study from Europe reported that use of other anorexigens (the most prevalent of which was dexfenfluramine) was also associated with an increased risk of PPH. This led to warnings of a repeat epidemic, especially after the introduction of dexfenfluramine on the North American market.

OBJECTIVE

To compare the epidemiologic associations of PPH with aminorex and dexfenfluramine, both with respect to strength of association (estimate of relative risk) and public health impact (etiologic fraction) and thus to assess the potential for a new epidemic of PPH.

METHODS

We constructed a "synthetic" case-control study for aminorex based on reported case series from Berne and Basel, Switzerland, and a random population sample from Hanover, Germany, and compared the results with those recently reported for dexfenfluramine. Control rates of exposure were used to estimate population exposure prevalences and, hence, etiologic fractions.

RESULTS

The estimated odds ratio (and 95% confidence interval) for the association between PPH and any exposure to aminorex was 97.8 (78.9-121.3), with a corresponding etiologic fraction of 77%. The corresponding figures for dexfenfluramine were 3.7 (1.9-7.2) and 17%, respectively.

CONCLUSION

The strong association between aminorex and PPH probably led to a 5-fold increase in PPH incidence, and thus a very noticeable epidemic. The association with dexfenfluramine would result in an increase in incidence of only 20%. Based on the available evidence, a repeat PPH epidemic seems unlikely.

Ethical issues in lung transplantation

Lung transplantation is now an accepted therapeutic option for many patients with incurable end-stage lung or pulmonary vascular disease processes for which other treatment options have been expended. However, as lung transplantation has evolved as a recognized discipline over the past decade, a variety of ethical issues related to the transplant process are emerging. This article considers those issues through a discussion of the four fundamental principles of biomedical ethics.

A close look at fenfluramine and dexfenfluramine

In an effort to combat obesity, several medications have been developed. The nonamphetamine anorectics, such as phentermine, fenfluramine, and dexfenfluramine, have been recommended as first-line drug therapy for the treatment of obesity once diet and exercise alone have failed. Numerous studies have shown that these agents can promote weight loss when combined with diet restriction and exercise. Although fenfluramine and dexfenfluramine lack the abuse potential of amphetamine and its congeners, these agents are associated with drug interactions and adverse effects. Concomitant administration of fenfluramine or dexfenfluramine with medications that enhance serotonin levels (e.g., antidepressants, monoamine oxidase inhibitors, and migraine medications) can precipitate serotonin syndrome. Sudden discontinuation of fenfluramine or dexfenfluramine after prolonged administration can precipitate withdrawal depressive symptoms. Primary pulmonary hypertension, a potentially fatal disorder, has been reported to occur approximately 30 times more frequently in patients receiving anorectic agents for more than 3 months compared to the general population. More recently, the association of these popular anorectics with valvular heart disease has caused increased concerns about their use. The risks of primary pulmonary hypertension, valvular heart disease, and the occurrence of convulsions, coma, and death in overdose appear to be equally likely with dexfenfluramine and fenfluramine. In addition, many patients who lose weight while taking these anorectics rapidly regain it after the medication has been discontinued.

High altitude may be synergistic with pulmonary hazards of appetite control medications fenfluramine and dexfenfluramine

Clinical observations over the past 15 years incriminated first fenfluramine and recently dexfenfluramine in the provocation of primary pulmonary hypertension. Limited animal toxicology data tend to support this inference. The basis for respiratory pathology of high-altitude pulmonary malfunction, which reaches its maximal level in high-altitude pulmonary edema, evolves from and depends upon the occurrence of pulmonary hypertension. For this reason we hypothesize that high altitude and these two anorexic medications constitute a potentially synergistic combination, of which physicians treating patients for high-altitude illness, as well as those prescribing the drugs, should be aware.

Obesity

Obesity is a chronic disease, which similar to diabetes and hypertension, requires long-term treatment. The patient must be willing to make major changes in eating habits, lifestyle, and physical activity to achieve long-lasting results.

Update on the pharmacotherapy of obesity

OBJECTIVE

To review recent developments in the pharmacotherapy of obesity, including the agents currently approved for use in the management of obesity and those under development.

DATA SOURCES

A MEDLINE search from January 1990 to July 1997 was conducted to identify English literature available on the pharmacotherapy of obesity. The search was supplemented by a review of the bibliographies of identified literature.

STUDY SELECTION

All controlled and uncontrolled trials were reviewed. When available, double-blind, placebo-controlled trials were used preferentially.

DATA EXTRACTION

Agents were reviewed with regard to mechanism of action, clinical trial data regarding efficacy, adverse effects, pharmacokinetics, drug interactions, and contraindications where information was available. Study design, selected population, results, and adverse effect information were included.

DATA SYNTHESIS

The anorexiants currently available or under development for the management of obesity regulate food intake and satiety via the adrenergic and/or serotonergic pathways. Clinical trials have shown a 10-15% weight loss can typically be anticipated; however, little long-term safety and efficacy data are available. Adverse events tend to be mild and self-limiting, but serious adverse events can occur. Treatment options under development include thermogenic agents, digestive inhibitors, and analogs and antagonists of hormones that regulate food intake and satiety.

CONCLUSIONS

Several mechanisms to control weight are currently under investigation for the management of obesity. Since obesity is a chronic condition, further studies should be conducted to evaluate the long-term safety and efficacy of these agents and the role of combination therapy using different modalities.

Long-term drug treatment of obesity in a private practice setting

This study evaluated the long-term efficacy and safety of the combination of phentermine and fenfluramine for the treatment of obesity in a private practice setting. A total of 1388 consecutive, qualified patients presenting to a private general internal medicine practice in Charlotte, NC, were enrolled with eligibility criteria including: age 18 years to 60 years, 20% over "desirable" bodyweight or body mass index > 27, no serious medical or psychiatric disease, and no contraindications to drug therapy. Patients were instructed in diet, exercise, and behavior modification techniques and received phentermine (15 mg/day to 30 mg/day) and fenfluramine (20 mg/day to 60 mg/day) continuously for over 3 years. Average duration of treatment was 15.9 months, and average weight loss at the last visit was 11.6 kg, or 11.7% of initial bodyweight. For patients completing 1 year of drug treatment, mean weight loss was 16.5 kg, or 16% of initial weight. Weight loss persisted for 2 years, but partial regain was seen at 3 years. The dropout rates were 18% at 6 months, 39% at 1 year, 68% at 2 years, and 78% at 3 years. At 1 year, blood pressure of hypertensive patients fell from 151/95 mm Hg to 127/78 mm Hg, and serum cholesterol and triglycerides of hyperlipidemic patient fell by 0.750 mmol/L (29 mg/dL) and 0.937 mmol/L (83 mg/dL), respectively. Adverse events were modest. We conclude that, in a private practice setting, long-term treatment of obesity with the combination of phentermine, fenfluramine, and a weight maintenance program is generally safe and effective. More research is needed to determine efficacy and safety for longer than 3 years.

Epidemiology of advanced lung disease in the United States

ALD affects a large segment of the population in the United States, both old and young, and men and women of all races and ethnicities. Many chronic diseases inevitably advance to a stage that results in significant respiratory impairment and disability. Although the causes of some of the diseases are known and the diseases may be preventable, the overall absolute burden of illness in the population is rising because of an enlarging population and newer therapeutic approaches. This is evident despite the lack of consistent and comparable data estimates for all diseases from national database resources. Where the data exist, it is evident that the cost related to the morbidity and mortality of these illnesses is substantial and consumes a significant proportion of health care expenditures. Both morbidity and mortality estimates, as well as cost estimates, are conservative and are likely underestimates of the true overall impact of ALD on the US economy.

Valvular heart disease associated with fenfluramine-phentermine

BACKGROUND

Fenfluramine and phentermine have been individually approved as anorectic agents by the Food and Drug Administration (FDA). When used in combination the drugs may be just as effective as either drug alone, with the added advantages of the need for lower doses of each agent and perhaps fewer side effects. Although the combination has not been approved by the FDA, in 1996 the total number of prescriptions in the United States for fenfluramine and phentermine exceeded 18 million.

METHODS

We identified valvular heart disease in 24 women treated with fenfluramine-phentermine who had no history of cardiac disease. The women presented with cardiovascular symptoms or a heart murmur. As increasing numbers of these patients with similar clinical features were identified, there appeared to be an association between these features and fenfluramine-phentermine therapy.

RESULTS

Twenty-four women (mean [+/-SD] age, 44+/-8 years) were evaluated 12.3+/-7.1 months after the initiation of fenfluramine-phentermine therapy. Echocardiography demonstrated unusual valvular morphology and regurgitation in all patients. Both right-sided and left-sided heart valves were involved. Eight women also had newly documented pulmonary hypertension. To date, cardiac surgical intervention has been required in five patients. The heart valves had a glistening white appearance. Histopathological findings included plaque-like encasement of the leaflets and chordal structures with intact valve architecture. The histopathological features were identical to those seen in carcinoid or ergotamine-induced valve disease.

CONCLUSIONS

These cases arouse concern that fenfluramine-phentermine therapy may be associated with valvular heart disease. Candidates for fenfluramine-phentermine therapy should be informed about serious potential adverse effects, including pulmonary hypertension and valvular heart disease.