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The weight loss industry is big business for prescription drug companies. Among prescription appetite suppressants, phentermine is the most commonly prescribed FDA-approved drug for weight loss, accounting for 50% of these prescriptions. It gained popularity because it is much cheaper than other diet drugs that are also FDA-approved including Meridia and Xenical.

The beginning of phentermine

Phentermine has been around since the 1950s. In 1959, it was approved by the FDA (Food and Drug Administration) as an effective and short-term appetite suppressant to treat obesity. From there, as technologies developed, phentermine resin became available by prescription in America in 1959. A little over a decade later, phentermine hydrochloride was available in the early 1970s.

Phentermine is currently sold in the US as Ionamin® by Medeva Pharmaceuticals and Adipex-P® by Gate Pharmaceuticals, however it can also be purchased in generic form, which is what is known as phentermine. It was once sold as Fastin® which was produced by King Pharmaceuticals for the brand SmithKline Beecham, however in December of 1998, the company withdrew this product from the market.

Phentermine is now an older drug and due to that, the conduction of new efficacy trials has not occurred on the product alone. However, in the 1990s, there were several trials conducted that combined phentermine with fenfluramine, which led to impressive results.

Powerful trends that almost upstaged phentermine

Back in the 1990s, Fen-Phen was a cocktail of prescriptions designed for weight loss. It worked impressively too. Fen-Phen was a combination of fenfluramine (or pondimin) and phentermine. Fenfluramine was approved by the FDA in 1973 for its ability to treat short-term obesity. Used together, this combination led to fast and effective results.

However, the FDA never approved the use of these two drugs together. Because each part of this prescription combination was approved separately though, doctors were allowed to prescribe it at will. This practice is what is known as “off-label.”

The Fen-Phen combination received more accolades in 1992 when Dr. Michael Weintraub of the University of Rochester and his colleagues published a study about Fen-Phen. In it, they noted it was more effective for weight loss than dieting or exercising. They also noted it had no immediate side effects. With this news, it catapulted Fen-Phen to the most prescribed combination with 6.6 million prescriptions in 1996.

There was also Dexfen-Phen, where dexfenfluramine (or redux) was combined with phentermine. Like the Fen-Phen combination the dexfenfluramine was also FDA-approved. In 1996, this prescription also took off running overnight. The problem was that no one tested either of these prescription diet combinations for safety.

Safety concerns caused changes in the market

The Mayo Clinic reported in the summer of 1997 a whopping 24 cases of heart valve disease, all directly linked to taking the Fen-Phen combination. This prompted the FDA to issue a Public Health Advisory based on those findings on July 8, 1997. There were further reports presented to the FDA about heart disease from patients that had taken only fenfluramine or dexfenfluramine.

When further evaluations were conducted, it showed that nearly 30% of the patients had abnormal valve findings. That’s a much higher number than expected, which led them to conclude that fenfluramine and dexfenfluramine were the likely causes of PPH (primary pulmonary hypertension) and valvular heart disease.

The FDA responded with a request for removal

Once these findings were known, the FDA issued a request to drug manufacturers in September of 1997 to remove the drugs fenfluramine and dexfenfluramine from the market. The FDA also publicly urged the public to either take one drug or the other but not both of them together. The FDA never requested phentermine to be withdrawn because it was never shown to cause side effects.

Another combination emerges with Phen-Pro

A different prescription cocktail involving phentermine is the latest combination. It’s called Phen-Pro, with the “pro” coming from Prozac. It is common for any of the other antidepressants like Zoloft, Luvox, Celexa, Trazadone or Effexor to be used instead of Prozac. What it does is it allows the phentermine to work better and for a longer period of time without the kind of damage that the other prescription cocktails caused. No reports have been issued for this combination.

Scams involving phentermine

Because phentermine has enjoyed such success, many companies have created non-prescription imitations of phentermine using similar names like phentarmine or phentramine. They sell them online but the problem is that authentic phentermine is not allowed to be sold online. With these restrictions, the US government has made it impossible to buy from the internet.

Safe phentermine alternatives

Phentermine’s website, does recommend one thing if you don’t have a prescription for phentermine. It’s called Phen Caps. These are an incredibly effective supplement for weight loss that provide similar effects to phentermine. Phen Caps work by curbing the appetite and boosting the metabolism. Energy levels also increase drastically, making it a great alternative. It has not been shown to cause any ill side effects and is available online for purchase without a prescription being required.


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