Finally bowing to the inevitable, Encysive Pharmaceuticals (NASDAQ:ENCY) announced today that it was planning an additional phase 3 trial to try and bring its lead drug to market in the United States.

Encysive's pulmonary arterial hypertension treatment Thelin has been issued three approvable letters, and also had an appeal of the approvable letters rejected after it first filed a marketing application for the drug back in 2005.

But the U.S. approval of Thelin has been blocked -- despite approvals in many other countries throughout the world -- by the FDA's lack of satisfaction that Encysive has proven the drug's efficacy, and its request for another clinical trial.

After conferring with "external experts," Encysive has also decided to give up on the dispute resolution process over Thelin with the FDA. Instead, it will focus on starting this clinical trial for the drug.

No specifics were given for the trial's start date or size, but Encysive did mention that it would be working with the FDA to finalize the study's protocol. That means it will be another few weeks at the earliest before the trial can begin.

Encysive's other pivotal phase 3 study, Stride-2, was an 18-week study that took 20 months from start to completion. If you count the three or so months that it will take Encysive to put together a marketing submission following the completion of the new study, and the six months minimum that it will take the FDA to review the data if the study is a success (which it should be), that puts Thelin on the market in the U.S. in late 2009 or early 2010, provided there are no bumps along the way.

With all the missteps in its attempts to bring Thelin to the market in the U.S., at least investors can feel comforted that Encysive is finally doing what it should have done after the second approvable letter back in July of 2006. It's too bad that Encysive's delay caused it to lose its U.S. lead over Gilead Sciences' (NASDAQ:GILD) Letairis, which gained regulatory approval in June.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. No approvable letters have been issued on the Fool's disclosure policy.