Merck halted the research of the experimental obesity drug taranabant because of the dangerous side effects it showed in clinical trials.

As stated by the pharmaceutical company on Thursday, people who were given the drug at a high dose uncovered anxiety and depression.

Abandoning the development of such a drug highlights how difficult is to create an efficient medicine able to help people lose weight.

Previously, the drug maker said the taranabant proved to be successful at certain dose levels in helping people fight against obesity. However, it was also linked to a great risk of psychiatric events, Merck said.

In spite of exiting obesity research, the company hasn’t give up to the idea of presenting data for the weight loss drug at an upcoming obesity-related conference.

Taranabant works by repressing appetite as a result of blocking a brain receptor.

According to analysts, by 2012, taranabant could have reached $500 million in sales.

The cannabinoid-based obesity therapy taranabant is in the same class of drugs as Sanofi-Aventis's Acomplia, which didn’t receive the Food and Drug Administration approval to be allowed in the US market because clinical data suggested that the slimming pill for obesity treatment may augment the risk of suicide.

It was the result of the last phase of human testing for regulatory approval that determined Merck to pull the plug on the development of the experimental obesity drug. "Available Phase III data showed that both efficacy and adverse events were dose related, with greater efficacy and more adverse events in the higher doses," stated John Amatruda, Merck's senior vice president and research head for diabetes and obesity.