A beefed up REMS and clearer picture of the safety profile for obesity candidate Qnexa phentermine/topiramate allowed Vivus Inc. to score a positive vote at last week's FDA advisory panel meeting, but the other two obesity candidates turned down by the agency can't count on finding the same success the second time around.

The reason: While all three candidates have safety signals that are difficult to exclude without large and lengthy trials, only Qnexa's efficacy has never been in doubt.