As investors in Wyeth (NYSE:WYE) and Elan (NYSE:ELN) found out: the devil is often in the details. It's not good enough to just see top-line results; sometimes the nitty gritty details -- only seen once the full results are presented at a conference -- are more important.

For Teva Pharmaceuticals (NASDAQ:TEVA), the details presented yesterday only confirmed the great initial report of the clinical trial success for its Parkinson's disease treatment Azilect. The drug slowed the development of the disease more than the placebo and met all three of its clinical endpoints at the lowest dose tested. Teva plans to submit the results to the Food and Drug Administration and European authorities to request an expansion of its label. The drug is currently indicated for the treatment of symptoms, but Teva now wants -- and should get -- wording stating that the drug slows the progression of Parkinson's disease.

Presenting the data now and at another meeting next month is a smart move for Teva. The meetings essentially act as marketing material for Azilect. Because this new information is not on the label, the sales reps can't tell doctors that Azilect slows the progression of Parkinson's disease, but nothing keeps Teva from sharing the data with the doctors at the meeting. Since Azilect is already approved, Teva is hoping they'll go home and write more prescriptions for their patients.

As good as the data is, Azilect, with $120 million in sales last year, has a long ways to go before it's the next Copaxone -- Teva's multiple sclerosis drug that's on pace to have sales top $2 billion this year. Parkinson's disease is actually a larger market in the U.S. compared to MS, but the competition is pretty tough. Azilect has to compete against generic versions of drugs like Bristol-Myers Squibb's (NYSE:BMY) Sinemet and with big-name drugs like GlaxoSmithKline's (NYSE:GSK) Requip, which also treats restless leg syndrome.

Even if it's not able to become the next blockbuster, the label change should help Teva increase sales of Azilect and every little bit helps.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Glaxo is a selection of the Income Investor newsletter. The Fool has a disclosure policy.