"...But I'll wait for something more, Yes I've got to have faith..." -- George Michael, "Faith"

Sometimes you've just got to keep the faith. For biotech AmylinPharmaceuticals (NASDAQ:AMLN), it has taken more than 10 years to secure approval for its first drug, SYMLIN, but with the company's announcement last night of approval by the Food and Drug Administration, the long wait has finally paid off.

Securing FDA approval for a new drugs is never easy (or cheap), but SYMLIN's history is even more tortured than most. More than 5,500 patients have taken SYMLIN in clinical studies, and the company has completed six phase 3 studies of the drug. (I've lost count of the number of phase 1 and 2 studies.)

Once left for dead by former partner Johnson & Johnson (NYSE:JNJ) years ago, SYMLIN was actually deemed "approvable" more than four years ago, but a variety of additional studies were demanded to quantify the optimal risk/benefit dosage.

So now what?

Although a variety of drugs have been approved for type 2 diabetes, SYMLIN is somewhat unique in that it is targeted at type 1 diabetics (and insulin-dependent type 2 diabetics). Designed to be injected before meals, SYMLIN acts in conjunction with a user's insulin therapy to improve blood glucose levels after meals.

What's more, SYMLIN seems to help lower the variability of blood glucose levels and has a moderate (but significant) weight-loss effect as well. Though obesity isn't a big problem with type 1 diabetics (as opposed to type 2 diabetics), who doesn't want to lose five pounds?

At present, many analysts don't see much in the way of a bright future for SYMLIN, and I think this is a mistake. While it's true that the idea of selling a non-insulin drug to type 1 diabetics is novel, I believe that the high level of attention given SYMLIN over its years of development should help the company's sales efforts. What's more, though it's true that hypoglycemia (too-low blood glucose) is a risk with SYMLIN, the long-term benefits of better glucose control for diabetics should outweigh this.

Although SYMLIN will never be a billion-dollar blockbuster, $200 million or more of annual sales is possible, and Amylin won't have to share that bounty with anybody. It retains full marketing rights.

The real story with Amylin, though, goes beyond SYMLIN. As fellow Fool Alyce Lomax pointed out, Amylin, along with partner Eli Lilly (NYSE:LLY), is positioned to be first-to-market with an entirely new type of drug for type 2 diabetes.

The drug in question, exenatide, is derived from Gila monster spit. It will likely be the first of the so-called GLP-1 analogs to hit the market. While direct competition could come from the likes of Novo Nordisk (NYSE:NVO), ConjuChem, and Sanofi-Aventis (NYSE:SNY), Amylin has at least a year's head start, and a long-acting formulation currently in trials could be a billion-dollar opportunity.

Amylin also has promising drugs in development for obesity and congestive heart failure, and the company is in a pretty good position with respect to cash liquidity, though the company does have nearly $400 million in debt.

Should investors take a shot with Amylin? Well, I own the stock myself, so I'm hardly an unbiased spectator. That said, I wouldn't be owning it if I didn't see significant potential for both the company and its drugs. While it is absolutely critical that you do your own due diligence, I still happen to think that Amylin shares are a bargain at today's levels.

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Fool contributor Stephen Simpson owns shares of Amylin Pharmaceuticals, Johnson & Johnson, and Sanofi-Aventis.