The Food and Drug Administration may be in one of its bipolar moods, but fortunately for Johnson & Johnson (NYSE:JNJ), it looks to be a manic phase.

After giving the company a complete response letter in February, the agency approved Risperdal Consta for the treatment of bipolar disorder. Apparently whatever was holding up the approval wasn't a major obstacle.

The drug, a long-lasting version of Risperdal designed with technology from Alkermes (NASDAQ:ALKS), is already approved for the treatment of schizophrenia. With Eli Lilly's (NYSE:LLY) long-acting injectable version of Zyprexa stuck in limbo, Johnson & Johnson needs to take advantage and get moving on the marketing of the drug to the expanded patient base.

Bipolar disorder isn't as severe as schizophrenia, so the main selling point of Risperdal Consta -- biweekly administration -- won't be as big a selling point over Risperdal, which recently went generic. But there are a certain subset of patients having trouble staying on daily meds like Risperdal, AstraZeneca's (NYSE:AZN) Seroquel, or Pfizer's (NYSE:PFE) Geodon, and Johnson & Johnson should be able to capture that market.

After Vanda Pharmaceuticals' (NASDAQ:VNDA) surprise approval earlier this month and the relatively quick reversal that Johnson & Johnson received, it's tempting to suggest that the FDA may be lightening up on approval requirements, but I'd like to see a few more approvals before we break out the champagne. Investors should continue to factor in a delay for any potential approval when valuing companies and make sure development-stage companies have enough cash to get through a delay. A conservative approach might result in missing a few big ones, but it'll reduce the risk considerably.

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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.