Weight Loss, Dieting & Obesity

Prescription Weight Loss Medications - Banned and Withdrawn Drugs.

Please read Part One of this series of articles on Weight Loss Medications before continuing. It contains important advice applicable to all forms of weight loss medications.

Many weight loss medications and drugs have been withdrawn from testing due to either lack of results or because of serious adverse reactions, either in animal or human studies. These drugs never had regulatory approval, nor made it to the market place. Accordingly, interest in these failed/withdrawn experiments are really not of general interest to most visitors of this website.

On the other hand, there are those weight loss medications that did have regulatory approval and which did make it into the market place, only to later be banned or withdrawn due to serious side effects that came to light too late. Either non-evident or possibly even concealed during clinical trials, when these weight loss drugs gained widespread use, the truth was unable to be hidden. The disasters came to light.

Why is it important for you, today, to know about these failed, dangerous, now banned or withdrawn medications? Put simply, scientists make mistakes. Regulatory authorities make mistakes. Consumers pay for these mistakes with their lives. How can you be sure that any weight loss medication currently on the market today, maybe even the one you are using right now, isn't also a death trap waiting to be revealed?

The bottom line is that artificial, laboratory made chemicals added to the human body should always be viewed as a last resort after all more natural and safer methods of treatment have been seriously tried. Weight loss drugs, along with weight loss surgery, should be considered the treatments of absolute last resort. Never think of weight loss drugs as an easy answer or quick fix. They all have known side effects, even those with full regulatory approvals. As the following examples show, even approved weight loss medications can have side effects far more serious than you would ever care to risk, up to and including death.

Fenfluramine Hydrochloride (a.k.a. Pondimin, Ponderax, Ponderal) Fenfluramine was introduced to the U.S. market after receiving regulatory approval in 1973 and became available throughout most of the world shortly thereafter. It was the "Fen" part of the highly popular and apparently successful "Fen-Phen" weight loss phenomena from the 1970s through to the 1990s. (The other half, the "Phen" component, was Phentermine, which remains on the market today, despite it being the far more physically addictive amphetamine-related drug.)

Fenfluramine worked by increasing the level of the neurotransmitter (brain chemical) Serotonin, which regulates mood, appetite and other forms of satiety, and other neurological functions. As such, it is closely akin to modern day SSRI-type antidepressants.

After many deaths and ongoing reports of cardiovascular related complications (heart valve disorders, pulmonary hypertension & cardiac fibrosis), it was withdrawn form the market worldwide in 1997.

Dexfenfluramine Hydrochloride (a.k.a. Redux, Adifax) Dexfenfluramine was a close relative of Fenfluramine (see above), used in the same way, approved at much the same time, was equally as popular as part of the "Fen-Phen" phenomena, had the same side effects and was subsequently withdrawn at the same time as its relative.

Click this link for more information on the FDA withdrawal of both Fenfluramine and Dexfenfluramine.

(Despite the worldwide withdrawal, occasional reports suggest that both of these dangerous obesity drugs are still available in Mexico, Spain and possibly some other countries.)

Interesting additional note: Most clinical studies of weight loss drugs are done over relatively short term durations. Few last beyond twelve months, most are only half that period. There was one published study of the Fen-Phen combination that lasted four years. It showed that maximum weight loss was within the first twelve months, continued though lesser weight loss up to two years, but even with the medications maintained the weight gradually returned after 104 weeks until almost all the lost weight had been regained at the end of the four year study.

Rimonabant (a.k.a. Acomplia, Zimulti, or unauthorized Indian generic versions Rimoslim & Slimona) Rimonabant was the first of a new class of anti obesity drug, designed as a cannabinoid blocker in the brain, liver, adipose (fat) cells, gastrointestinal tract and muscle tissue. It is well known that people who smoke cannabis get "the munchies", being stimulated cannabinoid receptors leading to stimulated appetite. The idea of Rimonabant / Acomplia / Zimulti was to block these receptors and so decrease appetite, leading to weight loss.

Rimonabant was never approved in the U.S., even though it was approved and marketed by French pharmaceutical company Sanofi-Aventis in The European Union and a number of Latin American and Asian countries (approved in 38 countries in total) since 2005.

After several previous attempts at approval, in September 2008, the US FDA reiterated its decision not to authorise Rimonabant / Acomplia / Zimulti when all trial results were presented and studied. The studies showed that although Rimonabant was successful at promoting sustained weight loss and also reducing numerous cardiovascular risks, the side effects were too numerous and widespread to allow Rimonabant onto the US market. These side effects included 26% of users reporting psychiatric symptoms ranging from anxiety and panic attacks to aggression and agitation, through to depression and increased suicide ideation. Additionally, 19% of trial users left the trial early due to vomiting and nausea.

Independent studies also suggested increased colorectal and possibly other cancer risks from Rimonabant use. Others indicated pregnancy complications such as ectopian pregnancies.

Shortly after the final FDA refusal, in October 2008 the European Medicines Agency called for the withdrawal of Rimonabant / Acomplia. By Early November 2008, Sanofi-Aventis obliged, withdraw the drug from production and announced a halt to further development of this drug.

Other recent withdrawals - Although never approved in any jurisdiction, quite a number of anti obesity and similar weight loss drugs have been under development by a range of drug companies. Numerous of these have already withdrawn their drugs from further testing. These include:

Otenabant (by Pfizer): Intended as a direct competitor to Rimonabant, Pfizer withdrew this drug from further trials in November 2008.

Taranabant (by Merck): Another intended competitor to Rimonabant. Merck voluntarily withdrew this drug from trials shortly before the withdrawal of Rimonabant due to side effects shown during testing.

MK-0557 (by Merck): Withdrawn from further testing in 2006 after early testing of this neuropeptide inhibitor found results only marginally better than a placebo.

PYY3-36 (by Merck): Withdrawn from further testing in 2006 after early testing of this hormone nasal spray found it to be ineffective.

711 (GlaxoSmithKline Plc): Testing was discontinued in 2005 after early testing indicated that it produced no result.

(Please bear in mind that the above list is not comprehensive as many studies and tests are never made public.)