On Wednesday, Amylin Pharmaceuticals (NASDAQ:AMLN) held its R&D day to update investors on the marketing strategy of its two diabetes products, as well as the development of its pipeline.

SYMLIN, the company's diabetes drug that is used in combination with insulin, is in a fairly small market -- last quarter, it racked up just a tenth of the sales that big brother Byetta made. In order to increase sales of SYMLIN, Amylin got a pen formulation approved by the FDA, which it plans to launch in January. The pens make it easier for the patients to inject themselves and have been used as a way to increase sales in other products, such as Sanofi-Aventis' (NYSE:SNY) SoloSTAR Pen for injecting its insulin product.

Real growth in sales for SYMLIN could come from a label expansion that would allow its use with basal insulin instead of just mealtime insulin. Amylin has received a not approvable letter for the label expansion already and hopes to address the FDA's concerns with its current trial comparing SYMLIN to rapid-acting insulin.

Byetta is currently approved for use in combination with other drugs like Bristol-Myers Squibb's (NYSE:BMY) Glucophage, but Amylin is trying to get it approved as a monotherapy to expand its potential patient population. Investors will know soon enough its chances of success, since the data from a trial to support the label expansion is expected before the end of the year.

Because the patients using Byetta are early in their diabetes disease progression, they are often on oral medications, but haven't started insulin yet. As a result, patients aren't used to injecting themselves and may be resistant to starting twice-daily injections of Byetta. In order to increase the number of patients interested in Byetta, the company is developing a once-weekly version called Exenatide.

Exenatide, developed using Alkermes' (NASDAQ:ALKS) microsphere technology, showed promising results in a recent phase 3 trial, but the New Drug Application won't be submitted until 2009. That's because the company needs to build a plant to make the drug and expects that the FDA may require it to do a bioequivalency study to prove the scaled-up version is the same.

Finally, Amylin updated investors about its weight-loss pipeline, where it's combining multiple naturally occurring hormones to try and get substantial weight loss in overweight patients. The combination in which it's furthest along -- leptin, which was acquired from Amgen (NASDAQ:AMGN) and is the active ingredient in SYMLIN -- showed pretty promising results earlier this month. Amylin plans to run a phase 2b trial to optimize the dose before starting a large phase 3 trial.

The near-term prospects for Amylin are in increasing its market by getting doctors to use its drugs earlier in the patients' disease progression, so those trials are really what investors should be keeping their eyes on. In the long term, the weight-loss pipeline has promise, but it still has a lot of risk associated with it.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.