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The most commonly observed, treatment-emergent adverse events associated with the use of dexfenfluramine in double-blind, placebo-controlled clinical trials were diarrhea (17.5%), dry mouth (12.5%), and somnolence (7.1%). These and other commonly observed adverse reactions were generally mild and transient. (Commonly observed is defined as incidence of 5% or greater and incidence in dexfenfluramine group at least twice that of placebo group, as derived from the Table 3 below.)
Associated with Discontinuation of Treatment
Seven percent of the 1159 patients who received dexfenfluramine in double-blind, placebo-controlled clinical trials discontinued treatment because of an adverse event. The most common adverse events resulting in discontinuation included asthenia, insomnia, headache, and depression. Five percent of the 1138 placebo-treated patients discontinued because of an adverse event.
Incidence in Controlled Clinical Trials
The following Table 3 lists treatment-emergent adverse events from several double-blind, placebo-controlled trials that occurred at a frequency of 2% or more among patients treated with dexfenfluramine and occurred at least as frequently as the placebo group, regardless of relationship to study medication.
Other Events Observed in Controlled Clinical Trials
The events below are classified within body system categories and enumerated in order of decreasing frequency using the following definitions. Frequent adverse events are those occurring in more than 1/100 patients but were not described above because the frequency in dexfenfluramine-treated patients was less than that in placebo-treated patients or they occurred at a rate less than 2%. Infrequent adverse events are those occurring in 1/100 to 1/1000 patients, while rare adverse events are those occurring in only one patient during placebo-controlled clinical trials.
Body as a whole:
Hemic and lymphatic system:
Metabolic and nutritional:
Infrequent: tremor, amnesia, euphoria, decreased libido, incoordination, neuralgia, speech disorder, ataxia, hypokinesia, sleep disorder, abnormal gait, agitation, confusion, depersonalization, diplopia, hostility, hyperesthesia, hyperkinesia, peripheral neuritis.
Skin and appendages:
Rare: skin hypertrophy.
Rare: spontaneous abortion, threatened abortion, breast neoplasm, endometrial disorder, female lactation, hematuria, impotence, mastitis, nephritis, prostatic disorder, testis disorder, urinary incontinence, urinary retention, uterine hemorrhage.
In controlled clinical trials, there has been no consistent pattern of laboratory abnormalities in patients treated with dexfenfluramine.
Voluntary reports of adverse events temporally associated with dexfenfluramine that have been received since market introduction in countries other than the US, for which the association with the drug is unknown, and which are not included in descriptions of adverse events elsewhere in this labeling, include the following:
Cardiovascular system: pulmonary hypertension (see WARNINGS), atrial fibrillation, cardiomyopathy, cerebral vasculitis, ECG abnormal, heart arrest, heart failure, myocardial infarction, myocarditis, shock, tachycardia, ventricular fibrillation, ventricular tachycardia.
Digestive system: dysphagia, gastrointestinal disorder, tongue disorder. Endocrine system--diabetic coma.
Nervous system: antisocial reaction, apathy, cerebellar ataxia, cerebrovascular accident (including cerebral hemorrhage, cerebral infarction, cerebral ischemia and cochlear infarction), choreoathetosis, convulsions, decreased reflexes, delirium, drug dependence, dyslexia, encephalopathy, grand mal convulsions, Guillain-Barré syndrome, hemiplegia, hypoesthesia, manic-depressive psychosis, manic reaction, memory loss, meningism, meningitis, neuropathy, papilledema, paraplegia, personality disorder, reflexes increased, retrobulbar neuritis, schizophrenic reaction, stupor, subdural hematoma, twitch, withdrawal syndrome.
Adverse Events Occurring After Discontinuation
In controlled clinical trials and/or in post-marketing reports, symptoms have been reported within a few days after discontinuation of dexfenfluramine. These include one or more of the following: abdominal pain, anxiety, asthenia, delusion, depression, diarrhea, dizziness, hypertension, insomnia, nausea and vomiting.
DRUG ABUSE AND DEPENDENCE
Controlled Substance Class
Dexfenfluramine is a controlled substance in Schedule IV.
Abuse and Physical and Psychological Dependence
Dexfenfluramine is not an amphetamine or a stimulant. There is no evidence of addictive or drug-seeking behavior in pre-marketing clinical studies. Dexfenfluramine was inactive in rat and monkey self-administration, drug-discrimination, and place-preference models of abuse potential.
Read the Redux (dexfenfluramine (fda removed from us market 9/15/97)) Side Effects Center for a complete guide to possible side effects
In patients receiving nonselective monoamine oxidase inhibitors (MAOIs) (e.g., selegiline hydrochloride) in combination with serotoninergic agents (e.g., fluoxetine, fluvoxamine, paroxetine, sertraline, venlafaxine), there have been reports of serious, sometimes fatal, reactions. Because dexfenfluramine is a serotonin releaser and reuptake inhibitor, dexfenfluramine should not be used concomitantly with a MAO inhibitor (see CONTRAINDICATIONS).
At least 14 days should elapse between discontinuation of a MAO inhibitor and initiation of treatment with dexfenfluramine. At least 3 weeks should elapse between discontinuation of dexfenfluramine and initiation of treatment with a MAO inhibitor.
A rare, but serious, constellation of symptoms, termed "serotonin syndrome," has been reported with the concomitant use of selective serotonin reuptake inhibitors (SSRIs) and agents for migraine therapy, such as Imitrex (sumatriptan succinate) and dihydroergotamine. The syndrome requires immediate medical attention and may include one or more of the following symptoms: excitement, hypomania, restlessness, loss of consciousness, confusion, disorientation, anxiety, agitation, motor weakness, myoclonus, tremor, hemiballismus, hyperreflexia, ataxia, dysarthria, incoordination, hyperthermia, shivering, pupillary dilation, diaphoresis, emesis, and tachycardia. Dexfenfluramine should not be administered with other serotoninergic agents. The appropriate interval between administration of these agents and dexfenfluramine has not been established. The use of dexfenfluramine with other CNS-active drugs has not been systematically evaluated; consequently, caution is advised if dexfenfluramine and such drugs are prescribed concurrently.This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 12/8/2004
Additional Redux Information
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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