Arena Pharmaceuticals shares increased 60 cents, or nearly 13 percent and closed at $5.26, even after FDA experts gave a negative recommendation.

The weight-loss drug, lorcaserin is being manufactured by the Company, which has rivals like Vivus' Qnexa and Orexigen Therapeutics Inc.'s Contrave. A negative recommendation was issued on Qnexa last Thursday, by a panel of Food and Drug Administration experts. The experts highlighted side effects of the drugs including depression, heart-related issues, and memory and concentration lapses.

FDA has followed the advice of its expert panels, which has consequently led to a fall in Vivus shares by 45 cents, or 8.3 percent, to finish at $4.96, on Monday. The shares have tipped to a 52-week low of $4.69, earlier in the session.

Lorcaserin will be reviewed in the month of September by an FDA panel, as many analysts have quoted the drug's benevolent safety profile.

Concept Capital Analyst, Michael McCaughan said, “The Qnexa committee discussion and vote strengthens our view that none of the three applications will reach the market in 2010”.

He added that there would be a path ahead for these products in 2011. The key to the class of drugs will be the risk-management plans, shared McCaughan.