Fenfluramine was withdrawn from the U.S. market in 1997 after reports of heart valve disease and pulmonary hypertension, including a condition known as cardiac fibrosis.
Indication
For the management of exogenous obesity as a short-term (a few weeks) adjunct in a regimen of weight reduction based on caloric restriction.
Pharmacology
Used to treat obesity, Fenfluramine decreases caloric intake by increasing serotonin levels in the brain's synapses. Fenfluramine acts as a serotonin reuptake inhibitor. It also causes release of serotonin from the synaptosomes. This in turn increases serotonin transmission in the feeding centre of the brain which suppresses appetite.
Toxicity
Agitation and drowsiness, confusion, flushing, tremor (or shivering), fever, sweating, abdominal pain, hyperventilation, and dilated non-reactive pupils seem frequent in fenfluramine overdosage. Reflexes may be either exaggerated or depressed and some patients may have rotary nystagmus. Tachycardia may be present, but blood pressure may be normal or only slightly elevated. Convulsions, coma, and ventricular extrasystoles, culminating in ventricular fibrillation, and cardiac arrest, may occur at higher dosages. Less than 5 mg/kg are toxic to humans. Five-ten mg/kg may produce coma and convulsions. Reported single overdoses have ranged from 300 to 2000 mg; the lowest reported fatal dose was a few hundred mg in a small child, and the highest reported nonfatal dose was 1800 mg in an adult. Most deaths were apparently due to respiratory failure and cardiac arrest. Toxic effects will appear within 30 to 60 minutes and may progress rapidly to potentially fatal complications in 90 to 240 minutes. Symptoms may persist for extended periods depending upon the dose ingested.
Affected Organisms
Humans and other mammals
Biotransformation
Hepatic.
Absorption
Fenfluramine is well-absorbed from the gastrointestinal tract, and a maximal anorectic effect is generally seen after 2 to 4 hours.
Half Life
20 hours
References
•
Roth BL: Drugs and valvular heart disease. N Engl J Med. 2007 Jan 4;356(1):6-9.
[Pubmed]
Dexfenfluramine, also marketed under the name Redux, is a serotoninergic anorectic drug. It was for some years in the mid-1990s approved by the United States Food and Drug Administration for the purposes of weight loss. However, following multiple concerns about the cardiovascular side-effects of the drug, such approval was withdrawn.
Indication
For the management of obesity including weight loss and maintenance of weight loss in patients on a reduced calorie diet
Pharmacology
Used to treat diabetes and obesity, Dexfenfluramine decreases caloric intake by increasing serotonin levels in the brain’s synapses. Dexfenfluramine acts as a serotonin reuptake inhibitor. It also causes release of serotonin from the synaptosomes.
Toxicity
Symptoms of overdose include respiratory failure and cardiac arrest leading to death.
