According to Eli Lilly (NYSE: LLY), combining multiple drugs to treat a patient is for wimps. The company announced today a multimillion-dollar investment to design single biotech drugs that go after multiple targets.

Attacking multiple pathways has become the norm for many treatment areas. HIV drug cocktails attack multiple proteins the virus needs to replicate. Both Merck's (NYSE: MRK) Januvia and Onglyza from Bristol-Myers Squibb (NYSE: BMY) and AstraZeneca (NYSE: AZN) are used with other diabetes drugs such as metformin. Ditto for cancer; Bristol-Myers and Roche recently announced a partnership to combine their melanoma drugs.

But why combine the drugs into a single molecule when two individual drugs can be taken in combination? Lilly claims you can get better efficacy and reduced side effects.

I'll believe it when I see it. The company already has "several" multi-specific therapeutics, but they're all in preclinical development, so I get to remain skeptical for a little while longer.

My guess is that this push toward hitting multiple targets with one drug -- Abbott Labs (NYSE: ABT) and others are also trying similar strategies -- has more to do with competition than anything else. If you develop two drugs that go after two targets, it leaves you open to competition for one or the other; to gain a majority of the market, you have to be best in class for both targets. If you combine them into one molecule, the onus is on the competition to find a combination that can beat you.

The chance for higher sales is enough of a reason to give it a try; one plus one might actually be worth more than two. But the same math works on the drug design side as well. Designing drugs to attack one target is difficult enough, so combining multiple targets is likely to prove more troublesome than just attacking each individually. Only time will tell which equation will win.

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Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool owns shares of Abbott Laboratories. Motley Fool newsletter services have recommended buying shares of Abbott Laboratories. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.