There's no doubt in my mind the Food and Drug Administration should approve Clinical Data's (Nasdaq: CLDA) depression drug vilazodone. The drug passed two phase 3 trials with flying colors and minimal side effects. Vilazodone is clearly better than nothing.

Whether the agency will approve vilazodone is an entirely different question. It's that "better than nothing" that could trip up the drug as both phase 3 trials tested the drug against placebo. That's perfectly acceptable for a drug that treats an unmet need, but there are plenty of drugs available to treat depression: Forest Labs' (NYSE: FRX) Lexapro, Eli Lilly's (NYSE: LLY) Cymbalta, as well as plenty of cheap generics.

I for one don't think the FDA should base its decision on whether the drug works better than other drugs. If Clinical Data wants to launch a drug without ever comparing it to currently available drugs in a head-to-head trial, let the company. As long as it's safe and effective enough, let the marketplace decide whether the drug should be prescribed. Unfortunately for Clinical Data bulls, I don't work at the FDA.

If the FDA does decide to punt back to Clinical Data for more data, it'll do so under the auspice of not knowing the risk-benefit analysis. Pfizer's (NYSE: PFE) Pristiq was approved in 2008 based on trials comparing it to placebo, but it had four trials instead of just two. And Pristiq is just a modified form of Effexor, so the agency had considerable familiarity with the drug's mechanism. Keep in mind that the FDA has gotten considerably more conservative over the past few years, so what flew two years ago might not work today.

The FDA didn't hold an advisory panel to review the drug, which makes you think the reviewers might be comfortable with the available data. If the agency was really worried about the data, wouldn't it have polled its outside experts? Of course, maybe the FDA reviewers had made up their minds already and didn't need the experts to help make a decision.

Figuring out which way the FDA will side has become increasingly difficult. Personally, I'm guessing -- and it really is just a guess -- that the FDA will approve the drug. I'm less confident about Clinical Data's ability to sell the drug once it's approved, which has me sitting on the sidelines for this one.

We'll know soon enough. The PDUFA date is on Saturday, so we should get an announcement late on Friday assuming a decision isn't delayed. In the mean time, take our Foolish poll and let us know your reasoning in the comment box below.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.