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Diet drug controversy as US approves meds rejected by Europe

The decision from the Food and Drug Administration (FDA) to allow two anti-obesity drugs to be marketed in the US has been called into question by a senior doctor publishing in the BMJ.

Dr. Sidney Wolfe, founder of the health research group at Public Citizen, says that the fact these drugs have been banned by the European regulator "puts the FDA to shame."

Belviq (lorcaserin) and Qsymia (phentermine plus topiramate) are available as anti-obesity drugs in the US.

Both Belviq and Qsymia can be prescribed in the US in adults with obesity if they are also following a reduced-calorie diet and undertaking increased physical activity. Their level of obesity must be such that the body mass index (BMI) is at least 30, although the drugs are also approved by the FDA for use in less obese people if they also have certain weight-related conditions.

In Europe, on the other hand, the so-called diet drugs have been deemed too harmful for any weight-loss benefits to be worthwhile - the ratio of their risks to benefits is too high, according to the European Medicines Agency (EMA).

Dr. Wolfe says the dichotomy between the decisions from the two regulators on either side of the Atlantic has applied to other drugs in the past, and he suggests Americans are being put at risk. He concludes:

"Thus, two more diet drugs, following in the footsteps of the now banned phenylpropanolamine, dexfenfluramine, sibutramine and others, were found by the EMA to be too dangerous to be used for weight loss but are considered by the FDA to be 'safe enough' for Americans."

Evidence for and against Belviq

The FDA approved Belviq in June 2012 on the basis of three randomized, placebo-controlled trials involving almost 8,000 obese and overweight patients, with and without type 2 diabetes, who were given the drug for between 52 and 104 weeks.

Dr. Wolfe says that for an extra weight loss of 3%, the diet drug was associated with a 16% increase in more cases of heart valve damage. There was no "statistical significance" to this risk, but there was likewise "insufficient evidence" to rule out potential heart danger.

The FDA approval committee chairman is quoted in the BMJ article as stating that a "clinically meaningful increase" in the risk for valvular heart disease "could not be ruled out."

Cardiologist Sanjay Kaul, who voted on the FDA panel against approval of Belviq, is also quoted by Dr. Wolfe as saying: "Given the totality of evidence, the potential benefits of lorcaserin do not, in my opinion, outweigh the potential risks when used long-term in a population of overweight and obese individuals."

The FDA gave blog a response to Dr. Wolfe's comments on the heart valve damage associated with Belviq (lorcaserin):

"Regarding the comment about the 16% increase in FDA-defined valvulopathy, we acknowledge this finding and discussed echocardiogram data at length at both advisory committee meetings for lorcaserin."

Morgan Liscinsky, FDA media affairs officer, added:

"However, based on our review of receptor affinity and other information, we concluded that it was unlikely that lorcaserin increases the risk for valvulopathy at the approved dose."

Evidence for and against Qsymia

The FDA approved Qsymia in July 2012 on the basis of two randomized, placebo-controlled trials involving about 3,700 obese and overweight patients, with and without significant weight-related conditions. They were treated with the drug for one year.

Dr. Wolfe highlights that Qysmia was given the go-ahead for use in America after the Belviq approval, "despite concerns about its cardiovascular risk."

He cites examples in which there was a "significantly higher" proportion of patients with "pulse increases exceeding 10 beats per minute, a risk factor for cardiovascular disease."

He also lists evidence of potential arrhythmia-related side-effects, "metabolic acidosis," and problems with cognition, such as impaired memory and reduced concentration or attention.

The drug was approved in the US whereas EMA rejected Qsymia (branded Qsiva in the EU) - because, according to EMA, while clinically helpful weight loss was proven, this was outweighed by the risks.

Dr. Wolfe quotes the European drugs regulator as being "concerned about the medicine's long-term effects on the heart and blood vessels [...] and about the long-term psychiatric" and other effects.

Morgan Liscinsky gave MNT the FDA's response, saying that the balance of Qsymia's risks, "including cardiovascular and neuro-cognitive concerns" were weighed against the drug's benefits and "publicly discussed" at two advisory committee meetings of drug experts.

"After thorough consideration, Qsymia was voted for approval."

The media affairs officer added: "Qsymia's labeling recommends that prescribers monitor heart rate in all patients, especially those with cardiac or cerebrovascular disease."

The labeling also states that Qsymia is not recommended "in patients with advanced or unstable cardiovascular and cerebrovascular disease."

Which medicines regulator is right?

The controversy over regulators' decisions to approve or reject the marketing of so-called diet pills in the fight against obesity will remain for as long as the views of the FDA differ from those of the EMA.

Whether one or the other drug regulator is right or wrong, for people who do have legal access to the anti-obesity pills in the US, the ultimate decision over whether to use them or not comes down to a discussion between patient and doctor.

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