It seems the Food and Drug Administration may have misread Eli Lilly's (NYSE:LLY) New Drug Application. The drugmaker wanted an approval of its extended-release version of antipsychotic Zyprexa, but got an extended review instead.

In February of 2008, the agency sent Eli Lilly back to the drawing board because of "excessive sedation events" in people taking the drug. And then in January of this year, the FDA requested a risk evaluation and mitigation strategy (REMS). Finally today, Eli Lilly announced that the FDA had approved the drug, which will be called Zyprexa Relprevv.

That's with two Vs. A subtle hint that the drug is long-acting, perhaps?

Zyprexa Relprevv is injected once every four weeks, which should help schizophrenics adhere to their medication better than the daily oral version. Back in 2008, having a once-monthly regimen would have been a great advantage because the only competition would have been Risperdal Consta, which was developed by Johnson & Johnson (NYSE:JNJ) and Alkermes (NASDAQ:ALKS). Risperdal Consta, the long-acting version of Risperdal, has to be taken once every two weeks.

Unfortunately, the delay before the FDA signed off on the drug allowed Johnson & Johnson to pass Zyprexa Relprevv. The health-care giant developed a follow-on to Risperdal called Invega and followed up with a long-acting version called Invega Sustenna. That version uses Elan's (NYSE:ELN) NanoCrystal technology, which allows for once-every-four-weeks dosing.

Zyprexa Relprevv will still get some sales. Doctors with patients who are having trouble staying on Zyprexa may be inclined to switch to Zyprexa Relprevv to keep the active ingredient the same. But with the competition from Invega Sustenna, Eli Lilly won't have as easy a time getting patients to switch from other oral medications like Pfizer's (NYSE:PFE) Geodon and Bristol-Myers Squibb's (NYSE:BMY) and Otsuka's Ablify as it would have two years ago. Investors can thank the FDA for that.

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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.