Fenfluramine dependence

Quantitative Positron Emission Tomography Studies of the Serotonin Transporter in Humans Previously Treated with the Appetite Suppressants Fenfluramine or Dexfenfluramine

PURPOSE

The appetite suppressants fenfluramine and dexfenfluramine were widely prescribed before being withdrawn from the market in 1997. Both drugs are known to have the potential to damage brain serotonin (5-HT) axons and axon terminals in animals, including nonhuman primates. This study used quantitative positron emission tomography (PET) with [(11)C] McN5652, a serotonin transporter (SERT) ligand to determine whether humans previously exposed to fenfluramines showed reductions in SERT binding parameters.

PROCEDURES

Subjects previously treated with fenfluramines for weight loss (N = 15) and age-matched controls (N = 17) underwent PET studies with [(11)C] McN5652. Global and regional distribution volumes (DVs) of [(11)C] McN5652 were compared in the two subject groups using parametric statistical analyses.

RESULTS

Compared to controls, subjects previously exposed to fenfluramines had significant reductions in [(11)C]McN5652 binding in 14 of 15 regions of interest, more than four years after drug discontinuation.

CONCLUSIONS

These results are the first to provide direct evidence for fenfluramine-induced 5-HT neurotoxicity in humans.

Major depressive episodes and diet pills

A variety of medications used to assist with weight loss have been implicated in the precipitation or induction of depressive symptoms and disorders. This is true of a large number of phenylethylamine agents possessing psychostimulant properties, non-phenylethylamine psychostimulants (e.g., caffeine) and the serotonergic agent, fenfluramine. There is, as yet, no substantial evidence linking the more modern weight loss drugs, sibutramine and orlistat, to the aetiology of major depression. Nevertheless, when these drugs are used, major depression will continue to be an important clinical consideration because of the elevated frequency with which major depression occurs in obese patients, the contribution that major depression may make to poor outcomes in non-pharmacological weight loss treatment and because of the interplay between symptoms of depression and weight loss treatment.

"Diet pills" and major depression in the Canadian population

OBJECTIVE

To evaluate epidemiological associations between self-reported diet pill consumption and major depressive episodes (MDEs), using data from a large-scale, cross-sectional survey of the Canadian population.

METHODS

Data from the National Population Health Survey (NPHS) were used in this analysis. The NPHS interview included a brief version of the Composite International Diagnostic Interview (CIDI) depression section, known as the CIDI Short Form for Major Depression (CIDI-SFMD), as well as provision for self-reported medication use.

RESULTS

Approximately 0.5% of the population reported the use of diet pills. Diet pill use was more common among women than among men. At the time of data collection (1996-1997), the most commonly used medication was fenfluramine (since withdrawn from the market because of cardiovascular toxicity). The use of these medications was strongly associated with MDE: the annual prevalence among persons reporting use was 17.1% (95% CI, 8.6 to 25.6), approximately 4 times the underlying population rate.

CONCLUSIONS

Because the NPHS was a general health survey, and because self-reported exposure to these medications was relatively uncommon, the data did not permit a detailed multivariate analysis. These findings, however, indicate that depressive psychopathology is strongly associated with the use of appetite-suppressant medications.

Adverse neuropsychiatric events associated with dexfenfluramine and fenfluramine

1. There is a large body of evidence indicating that fenfluramines damage brain serotonin neurons in animals. 2. Little is known about potential adverse neuropsychiatric consequences in humans associated with use of fenfluramines that could potentially be related to serotonergic dysfunction. 3. The authors now report numerous cases of severe and, sometimes persistent, neuropsychiatric syndromes associated with fenfluramine use. 4. Thirty one representative cases are presented and summarized in table form. 5. Several of the cases presented suggest long-lasting deleterious effects of fenfluramines on brain serotonin function. 6. Clinicians should be vigilant for disorders of mood, anxiety, cognitive function and impulse control in patients previously exposed to fenfluramines.

Drug-induced depression. Incidence, avoidance and management

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R), drug-induced depression may be classified as an Organic Mood Syndrome, Depressed Type. Unfortunately, the DSM-III-R diagnostic criteria are not sufficiently precise for application in research, and studies of drug-induced depression have rarely utilised these criteria. Research concerned with drug-induced depression is characterised by a number of methodological complications. These include differing definitions of depression, including depression defined as a symptom, a syndrome, or by diagnostic criteria for a specific mental disorder. In addition, patients undergoing pharmacological treatments for medical illnesses are typically exposed to considerable psychosocial stress due to the suffering and disability associated with illness. These psychosocial factors may in themselves precipitate episodes of depression. Due to these complicating factors, sophisticated study designs are required to confirm an aetiological role for medications as risk factors for depression. Unfortunately, adequate studies have rarely been conducted, and much of the literature consists of case reports and clinical observations. Consequently, clinicians are frequently required to make clinical judgements about the aetiology of patients' depressive symptoms in the absence of definitive scientific information about the role of drugs. Nevertheless, a knowledge of the relevant literature will assist clinicians in making reasoned judgements about the aetiology, prevention and management of these disorders.

Neuropsychiatric adverse drug reactions: passive reports to Health and Welfare Canada's adverse drug reaction database (1965-present)

OBJECTIVE

Since 1965, Health and Welfare Canada has operated an adverse drug reaction (ADR) program. The program accepts spontaneous reports of adverse drug reactions, and maintains an ADR database. The purpose of this article is to summarize the Psychiatric ADRs reported to this database since 1965. The nature of the information prohibits its use in the evaluation of epidemiological hypotheses about the etiology of drug-induced mental disorders. However, in an exploratory sense, the contents of the database may contribute to the development of epidemiological hypotheses about the etiology of drug-induced mental disorders. Of particular interest are areas of apparent contradiction between the contents of the database and the clinical literature.

METHODS

The database was searched for reports of ADRs to a group of drugs which have been frequently implicated in causing psychiatric toxicity. All reports characterized as "psychiatric disorders" were down-loaded from the database for the analysis (n = 1822). The reports were further classified into nine categories according to the type of psychiatric symptoms described.

RESULTS

There were several reports of hallucinations caused by methyldopa, and also several reports of benzodiazepine-induced hallucinations and encephalopathy. These reactions have not been described in the literature. Also, there were few reports of digoxin-induced organic depression, and an absence of reports of organic mania induced by H-2 blockers, despite descriptions of these sorts of reactions in the clinical literature.

CONCLUSIONS

Further research is needed to define the neuropsychiatric toxicity associated with medical drugs. Clinicians must continue to consider the potential role of medications in the etiology of psychiatric symptoms.

Fenfluramine: a review of its pharmacological properties and therapeutic efficacy in obesity

Fenfluramine has been used for a number of years as a short-term adjunct to diet in the management of obesity. Controlled studies and clinical experience have shown that it possesses anorectic activity at least as good as that of other therapeutically useful drugs of its type, but like these drugs it has only a limited role in the overall management of obesity. Tolerance to the anorectic effects of fenfluramine may possibly develop more slowly than to other chemically related drugs in patients with refractory obesity. The mechanism of its anorectic action is probably by an effect on the appetite control centres in the hypothalamus, rather than by an effect on glucose and lipid metabolism. However, its effect in enhancing glucose uptake into skeletal muscle may be of advantage in diabetes mellitus, preliminary studies suggesting that it is of potential use in maturity-onset obese diabetics who cannot be adequately controlled by dietary measures alone. The starting dosage in obesity of 40mg daily should be increased gradually over 2 to 4 weeks to 60 to 120mg. In general, little extra benefit is gained by higher dosage. When a course of therapy is to be discontinued, fenfluramine dosage should be reduced gradually over a period of 2 to 4 weeks in order to avoid mood depression which has occurred in some patients on abrupt withdrawal of the drug. With these recommendations, the majority of patients tolerate fenfluramine satisfactorily, although some patients may have to discontinue the drug because of troublesome gastro-intestinal problems, diarrhoea, drowsiness or dizziness. Unlike other amphetamine-derived anorectics, fenfluramine is not a central stimulant in therapeutic doses, and it probably has little abuse potential.