Eli Lilly (NYSE:LLY) is late to the party, but it's getting gussied up anyway in the hopes of attracting at least a few new friends before the party winds down.

The company's blood thinner, Effient, was approved by the Food and Drug Administration last July. Its competition, Plavix from sanofi-aventis (NYSE:SNY) and Bristol-Myers Squibb (NYSE:BMY), was first approved in 1997. That's a mighty large head start for attracting patients.

In order to justify the use of Effient, Eli Lilly is touting a study published in today's Circulation demonstrating the cost effectiveness of Effient over Plavix. Even including the increased bleeding seen in patients on Effient, the drug still resulted in $530 less hospital charges per patient. Effient costs more than Plavix, but even when you factor in the cost of the drug, the medical costs were still $221 cheaper per patient.

There's just one problem: This party is about to get crashed by generic-drug makers. Plavix loses patent protection in a few years and the drug will certainly be available for cheaper. Based on a hypothetical $1 per day price for the generic, the study's authors calculated that Effient would still result in a lower cost in the first 30 days of treatment, but not after that.

The $1-per-day price is 22% of the branded-drug price, but it's possible that the price could be even lower. In an FDA study, drugs that had 14 or more manufacturers selling generic versions had a relative price of 16% or lower. Considering that Plavix is the second-best-selling drug behind Pfizer's (NYSE:PFE) Lipitor, I imagine there will be a lot of generic competition looking for a piece of the action.

We've reached an era where it's no longer good enough to just throw another drug in the same class out there and hope it sticks -- a la Wyeth's Pristiq and Johnson & Johnson's (NYSE:JNJ) Invega. Companies actually have to justify their drug's existence in order to get meaningful sales. While Eli Lilly may have trouble justifying Effient as a cost saver in a few years, it's still a better drug resulting in less hospitalizations, which patients may be willing to pay extra for.

Speaking of worth paying for, Shannon Zimmerman says this stock is up 100%, but still a bargain.

Johnson & Johnson is an Income Investor recommendation. To see how dividend-paying stocks can offer both secure income and the opportunity for growth, take a free look at this newsletter with a 30-day free trial. Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Pfizer is a recommendation of the Inside Value newsletter. The Fool has a disclosure policy.