Considering that it's been three years since Adolor (Nasdaq: ADLR) first tried to get approval for its lead drug, I'm sure another three-month wait for an FDA decision on the company's top drug isn't going to bother longtime investors too much.

Last week, the FDA informed Adolor and partner GlaxoSmithKline (NYSE: GSK) that they'd likely have to wait another three months -- until May 10 -- to get a decision on the U.S. marketing application for their post-abdominal-surgery constipation treatment, Entereg.

Adolor was originally expecting to hear back from the FDA by Feb. 10 about the Entereg marketing application. After an advisory-panel hearing to discuss the drug that took place three weeks ago (read about it here and here), Adolor decided to update its marketing application with new information about how it would prevent off-label usage of Entereg. This new data submission is what triggered the extra three-month FDA review time.

The advisory-panel meeting last month was relatively positive toward Entereg, as long as the drug is not prescribed off-label or for long-term use. The panel voted 13-0 that Entereg was effective in treating patients and 9-6 that the benefits of using Entereg were greater than its risk in certain post-abdominal-surgery patient populations.

There was one area in which the panel universally thought Adolor was deficient: its plan to prevent off-label usage of Entereg. The advisory committee voted 14-0 that Adolor's risk-management plan was not adequate. In its briefing documents, the FDA sounded a similar concern, and until Adolor strengthened its risk-management plan, it looked like the company wouldn't get final marketing approval for Entereg.

Adolor didn't give any clues as to the details of the new risk-management plan. That's unfortunate, since the plan will likely be the make-it-or-break-it factor in whether the FDA approves Entereg. Nonetheless, it was probably a smart idea to submit the new risk-management plan to the FDA now, rather than waiting for a highly likely approvable letter this month.

This strategy will likely mean Adolor must wait an extra three months before hearing back on its Entereg marketing application. But the turnaround time for even the shortest class 1 approvable letter is usually two months, plus the time it takes for the drugmaker to write up the approvable-letter response and for the FDA to accept it. Therefore, the extended review will probably not cost Adolor any more time than if it had waited for an FDA rejection.