Weight-Loss Drug MK-0557 Falls Flat

The weight-loss drug, known as MK-0557, will be shelved, though it produced encouraging results in animal studies, HealthDay News reported Tuesday, Oct. 3. According to the announcement of the pharmaceutical firm Merck & Co., the drug has failed in a real-world trial of humans. It was designed to affect a person's "hunger-stimulating factor", a potential target for any drug in anti-obesity therapy. But the 12-month study of 832 patients has shown the average weight loss to be only 7.5 pounds in comparison with the average loss of 4 pounds for people from the placebo group.

In October Cell Metabolism has published the results of 10-year study. Executive director of clinical sciences at Merck, lead researcher Dr. Steven B. commented that the amount of weight people had lost was not clinically meaningful and MK-0557 did not represent any commercial viability for a drug company.

According to Heymsfield, the drug caused significant weight loss in animal experiments. It is considered, that in the trial of humans, during which 1661 obese people were assigned to MK-0557 or a placebo, the receptor was also completely blocked. This trial has brought out the fact that a receptor called NPY5R, while associated with the food intake, is not a main pathway in regulating hunger. As an alternative solution, Heymsfield proposed the food intake to be regulated by a number of pathways that compensate each other in case of stoppage.

Dr. David L. Katz, an associate professor of public health and director of the Prevention Research Center at Yale University School of Medicine, thinks that the concept of a magic pill is the wrong approach to weight loss. According to his interpretation of the trial results there is no need in a cocktail of drugs, as in the main, drugs are not the right answer at all. According to Dr. David L. Katz the causes of epidemic obesity appear practically everywhere, but in the most part they are modifiable by the mustering of will. Though Dr. Katz doesn't reject the drugs at all, considering them as a part of a comprehensive treatment plan. There should be no absolute reliance on drugs as the means of weight control. The relative failure of MK-0557 can probably prompt investigators to devote less attention to blocking of the receptors in our mind, but to seek for the new opportunities for more healthful eating and more active behavior in everyday life.

The upshot of the experiments with rats, held by European researchers, is that the notion of "whetting the appetite" may have a biological basis, reported Cell Metabolism, October. The researches assert that the animals, trained to the strict feeding regimen, had spikes of brain activity in specific areas, considered to be responsible for hunger, when they ate the first bites of food.

Gareth Leng, researcher of the University of Edinburgh, attracted the attention to the appetizing effect of food, when the start of eating greatly stimulates the drive to eat. In this case food causes the actual switching on of the hunger circuits. The group under the direction of Lang has found that the brain cells involved in triggering hunger are activated by the expectation of food. The fact that the window for in the experiments with rats was brief can be explained by the proposal that switching on of the brain centers responsible for registering the feeling of fullness occurs at the same time as food hit their stomachs.