Outlook: Obesity

Published Online: Wednesday, April 11, 2012
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FDA Reconsiders Previously Rejected Obesity Drug

It has been 13 years since the FDA last approved a prescription drug to treat obesity, but that may soon change. In February, an advisory panel voted overwhelmingly to recommend approval of Qnexa, a drug that the same panel advised against approving and the FDA rejected due to safety concerns in 2010. Qnexa, manufactured by Vivus, is a combination of the appetite suppressant phentermine and the antiepileptic and migraine drug topiramate, which induces a sense of fullness. Both components are available separately, and topiramate is widely prescribed offlabel to treat obesity.

In clinical trials, Qnexa led to average weight loss of 10% in the first year of use, though some weight was regained in the second year. The drug seemed to have a beneficial effect on blood pressure and blood sugar, some blood lipids, and quality of life. However, it also increased heart rate, which some argue could lead to increased risk of heart attack despite its other salutary effects. In addition, when taken during pregnancy, topiramate has been shown to increase the risk of a baby being born with oral clefts 2 to 5 times.

To allay concerns about the drug’s cardiovascular risks, Vivus has proposed conducting a post-approval study on 11,300 patients over 4.5 years. The company has also agreed to a number of measures to limit access to the drug by pregnant women. The FDA is scheduled to make a decision on Qnexa by April 17. It may take the panel’s advice or it may require more study of the drug’s side effects before approval.

Several other obesity drugs that were rejected by the FDA in recent years are also angling for a second look. Arena Pharmaceuticals’ lorcaserin, which the agency rejected in 2010 due to cancer risks, will be considered by the advisory panel in May. And Oxigen Therapeutics is conducting a 2-year study of potential heart risks associated with its drug Contrave (bupropion and naltrexone), which the agency rejected in 2011.


Prescription Drugs Can Fuel Weight Gain

Certain prescription drugs can lead to significant weight gain or loss, and the Drug Information Center of the Harris County Hospital District in Texas is getting the word out about the phenomenon.

Health care providers including pharmacists should be aware that when medications induce weight gain, patients may stop taking them or reduce their dosage—both of which can affect their health. Pharmacists should encourage patients to discuss any drug-related weight changes with their physician.

According to the center, some of the key prescription drugs associated with weight change are as follows:

  • Diabetes medications: pioglitazone (Actos), glimepiride (Amaryl), and insulin are associated with weight gain. Exenatide (Byetta), sitagliptin (Januvia), pramlintide (Symlin), acarbose (Precose), and metformin are weight neutral or associated with weight loss.
  • Hypertension medications: metoprolol (Lopressor), atenolol (Tenormin), propranolol (Inderal), amlodipine (Norvasc), and clonidine are all associated with weight gain.
  • Antidepressants: paroxetine (Paxil), sertraline (Zoloft), mirtazapine (Remeron), and amitriptyline are associated with weight gain. Bupropion (Wellbutrin) and fluoxetine (Prozac) are weight neutral or associated with weight loss.
  • Antipsychotics: clozapine (Clozaril), olanzapine (Zyprexa), risperidone (Risperdal), quetiapine (Seroquel), and lithium are all associated with weight gain.
  • Antiepileptic drugs: carbamazepine, valproic acid, and gabapentin (Neurontin) are associated with weight gain. Lamotrigine (Lamictal), topiramate (Topamax), and zonisamide (Zonegran) are weight neutral or associated with weight loss.


Fat Suppresses Sperm Count

Overweight and obese men are at increased risk of having a low or nonexistent sperm count, according to the results of a meta-analysis published in the March 12, 2012, edition of Archives of Internal Medicine. The researchers carried out the meta-analysis to reconcile the fact that some studies have found that sperm count goes down as body mass index goes up, but others have not.

The meta-analysis was based on 14 studies, including 9779 participants in all. Its results showed that, compared with normal-weight men, overweight men have an 11% higher chance of having a low sperm count and a 39% higher chance of having a nonexistent sperm count, although the latter result was not significant. Likewise, compared with normal-weight men, obese men have a 42% higher chance of having a low sperm count and an 81% higher chance of having a nonexistent sperm count.

The researchers concluded that the data strongly indicate that excess body weight affects sperm production. As possible explanations for how this occurs, they suggested that male hormones could be transformed into estrogen in fat, or accumulated fat in the midsection could increase the temperature of the scrotum, impeding sperm production.



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