A number of companies are attempting to introduce a new generation of ‘diet pills’ (prescription weight loss drugs). However, the US Food and Drug Administration (FDA) has expressed concern about the risks associated with the pills and has previously rejected pills
from the companies Arena Pharmaceuticals Inc., Orexigen Therapeutics Inc. and Vivus Inc.
The company Vivus
has announced that it will be resubmitting its application (called a New Drug Application) for its product called Qnexa (a combination of the amphetamine phentermine
, which is already in use for short-term weight loss, and topiramate
, an anti-convulsant). The chemicals work by phentermine acting to suppress the appetite, and topiramate functions to make patients feel fuller (and therefore less keen to consume food).
According to PharmPro
, Vivus have declared that initial trials with the pills have led to an average 10% weight loss of total body mass amongst the adult volunteers who took the pills. These trials have come after the pills were first rejected in October 2010.
Vivus have said about the new trials
“Patients taking Qnexa have demonstrated statistically significant weight loss, glycemic control, and improvement in cardiovascular risk factors, when used in combination with a diet and lifestyle modification program. The most commonly reported side effects were tingling, dry mouth, constipation and altered taste.”
notes that Vivus will present new data, centered on drug safety information. The company will make a commitment to undertake further studies looking at patient physiology. Whether these need to be conducted before approval remains to be seen (this will be at the decision of the FDA).
This notwithstanding, the FDA continues to have concerns about safety issues associated with diet pills. These issues include potential heart problems, together with blood pressure issues, and birth defects in women who become pregnant while taking the drug. The biggest birth defect concern is cleft lip.
The topirimate component of the drug has been associated in the past with birth defects. The phentermine part of the drug has been previously associated with heart related medical issues (in the 1990s the FDA required the company Wyeth to recall drugs containing the chemical).
Further health concerns based on the first examination of the data included suicidal thoughts and memory lapses.
In the new application, Vivus are planning to add to the product insert (which gives details and limitations on the product’s use) a note that pregnant women should not take the pills.
Whether the Vivus application will progress will be partly decided by a panel of medical doctors (a federal advisory panel), which is scheduled to meet on February 22. The question being considered is whether the "overall risk-benefit assessment of Qnexa is favorable to support approval". The decision by the panel is not binding but it is influential on the FDA and the Agency will make the final decision in April 2012.
According to USA Today
, the arguments in favour of the pills related to US obesity rates, which stand at 35% among adults. For pharmaceutical companies, the invention and licensing of a diet pill is likely to be very lucrative. Currently there is only one prescription drug on the market for long-term weight loss: Xenical
(manufactured by the Swiss Pharma giant F. Hoffmann-La Roche Ltd), although this product only claims that it can achieve a relatively modest weight loss result.
Whether the medical panel grants approval for Qnexa appears to be in the balance. Even if the decision is yes, the high hurdle set by the FDA remains a further obstacle to be cleared come April.