Getting a drug candidate approved is only half the battle, as Swiss pharma Novartis (NYSE:NVS) is showing with its diabetes treatment Galvus.

The European Union equivalent of the FDA, the European Medicines Agency (EMEA), approved Novartis' new type 2 diabetes drug, Galvus, in September. Along with Merck's (NYSE:MRK) already approved JANUVIA and a Bristol-Myers Squibb (NYSE:BMY) drug candidate, Galvus represents the first in a new class of type 2 diabetes treatments -- commonly known as DPP-4 inhibitors -- that help the pancreas produce more insulin.

Unfortunately for Novartis, after the EMEA approval, new data came out showing that the drug's use at higher dosage levels led to an increased risk of higher liver enzyme levels in some patients. Many a drug has failed to get approved or been pulled from the market when it was found to cause liver enzyme levels to go up, because if liver enzyme levels remain elevated, it can cause liver damage and sometimes death.

To give itself and regulators time to parse the new data (and perhaps in an attempt to avoid a repeat of GlaxoSmithKline's (NYSE:GSK) troubles with Avandia), Novartis delayed its European marketing launch of Galvus. On Monday, the company announced that the EMEA had again recommended allowing Galvus on the market, but with a requirement for liver enzyme monitoring and elimination of the more potent once-a-day dosage level. Galvus will still have a lower-dose once-a-day treatment available.

The EMEA process for drug approval (or reapproval, in this case) is a little different than in the U.S., so Novartis will still have to wait two to three months for procedural reasons before the EMEA will allow Galvus to be marketed to its member states. Based on this timeline, Novartis expects to launch the drug in the "first half of 2008."

The Galvus stumbling blocks in the U.S. have been a little more daunting. After delaying its review of the drug for several months last year, the FDA issued Novartis an approvable letter in February and asked for more safety and efficacy data on the drug in diabetics with kidney impairment. This necessitated another clinical trial and likely a long delay until the drug will be available in the U.S.

Now that Galvus will be available in the EU, we can finally see how well the drug competes in the marketplace against Merck's once-a-day JANUVIA. Galvus will be at a disadvantage without its higher-dose treatment, as the higher dose may have been more efficacious than JANUVIA, whereas the lower doses fare more equally in efficacy.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. Glaxo is a selection of the Income Investor newsletter. The Fool has an A+ disclosure policy.