It's a tough marketing world out there. To get drugs prescribed, companies have to show their products are different enough from their rivals. I'm not sure if Endo Pharmaceuticals (Nasdaq: ENDP) has hit the mark with its treatment for low testosterone, which the Food and Drug Administration approved yesterday.

This isn't the first testosterone treatment. Abbott Labs (NYSE: ABT) has one called AndroGel and Auxilium Pharmaceuticals (Nasdaq: AUXL) sells one under the brand name Testim. The selling point here seems to be that Endo's gel is applied to the inner thigh. Because there's evidence that it's bad to have testosterone rub off on children, Endo figures the thigh is more likely to be covered than the abdomen, where AndroGel is applied, or the shoulder, where Testim is applied.

What's the market size of men with low testosterone who run around with their shirt off? I have no idea, but I would have guessed those were two fairly mutually exclusive groups.

Maybe the name, Fortesta, will help sell the product by conjuring images of building a fort in the backyard. I'm not really sure where Endo was going with the name.

Endo also has the challenge of having a competitor, Eli Lilly (NYSE: LLY), with a one-month head start launching a new product into the same space. If Eli Lilly's sales reps get to doctors first, they might be able to convince them that patients are more likely to prefer its testosterone replacement, Axiron, which is applied with an underarm applicator like deodorant.

Having Eli Lilly launching at the same time might not be all that bad, though. Low testosterone is an underdiagnosed syndrome, and the larger pharmaceutical company may end up throwing marketing money at the problem to get patients diagnosed. Even if Endo only gets a portion of the market, if the market expands enough, Fortesta could end up bringing in a fortress full of cash for Endo.

Interested in any of these stocks? Add them to My Watchlist.

Motley Fool Rule Breakers is always on the hunt for hot drug stocks and other cutting-edge picks. See all of our latest discoveries with a free 30-day trial subscription.

Fool contributor Brian Orelli, Ph.D., has never been tested for low testosterone, but he does tend to keep his shirt on. He doesn't own shares of any company mentioned in this article. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Motley Fool Alpha owns shares of Abbott Laboratories. The Fool has a disclosure policy.