Let's talk about Elan (NYSE:ELN) this week. And of course, when I say Elan, I'm pretty much boiling it down to its Tysabri drug. A lot of the Irish drug maker's future is banking on the success of its multiple sclerosis drug, but does that make Elan a one-trick pony?

Wide product lines and deep pipelines are a blessing, but that's not the only way to win the game. I saw Amgen (NASDAQ:AMGN) blaze through the 1990s on the heels of just two blockbuster drugs in Neupogen and Epogen.

And maybe having a diversified drug portfolio is overrated. As big as Pfizer (NYSE:PFE) is, it's still trading a third lower than where it was three years ago. Other Big Pharma names like Merck (NYSE:MRK) and Bristol-Myers Squibb (NYSE:BMY) are starting to bounce back, but they're still far off their all-time highs.

So where does that leave us when it comes to Elan? Well, we're not all in agreement. Anders Bylund is feeling bullish about the drug maker's chances, while Brian Lawler is donning his flame-retardant suit to tackle the bearish case.

Who will win? It's Elan's story, now.

Duel on!

Pfizer is an Inside Value recommendation, while Merck is a former pick in the Income Investor newsletter. Check out either service free for 30 days once you're done with the Duel.

Rick Munarriz does not own shares of any company mentioned. The Fool has a disclosure policy.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.