For a drug that Pfizer ( PFE) says will be an important addition to its arsenal, Lyrica is getting a slow release in the U.S.

The drug was approved by the Food and Drug Administration on Monday as an add-on treatment for epilepsy, but Pfizer says the product won't be available until this fall. Lyrica also was approved by the FDA in December as a treatment for pain associated with shingles and for nerve pain associated with diabetes. At the time, Pfizer said the drug would reach the market "in the near future."

The drug isn't on the market for any of the FDA-approved uses because it has been declared a controlled substance and must be reviewed and classified by the Drug Enforcement Administration. Rebecca Hamm, a Pfizer spokeswoman, said Monday the company hopes to get the lowest of five DEA classifications, meaning the drug has the least chance for abuse or misuse.

But the DEA hasn't made a decision, and it can take many months to classify a controlled substance. For example, it took nearly four months for the DEA to sign off on the sleep drug Lunesta from Sepracor ( SEPR) before the drug became available in the U.S. in early April.

Lyrica has been viewed by Pfizer as a successor to Neurontin, which had $2.73 billion in sales last year and which is under ferocious attack by generic competitors. Neurontin is approved for seizures and for pain associated with shingles.

During the first quarter of 2005, Neurontin recorded $182 million in worldwide sales, down 74% from the same quarter last year. The U.S. component fared worse: first-quarter 2005 sales dropped 90% to $56 million.

Meanwhile, Lyrica produced only $20 million in revenue during the first quarter of 2005, thanks to foreign market sales. Analysts say Lyrica has several advantages over Neurontin -- it can treat more diseases, it's more potent, it has fewer interactions with other drugs, and it's easier to take.

Pfizer had hoped to secure FDA approval last fall, but the agency gave conditional approval in September for Lyrica as an epilepsy treatment. At the same time, it also gave conditional clearance of the drug for treating pain associated with shingles and nerve pain associated with diabetes.

The agency also rejected Pfizer's petition that Lyrica be used as a treatment for generalized anxiety disorder. Hamm said Pfizer intends to continue pursuing FDA approval of the drug for this indication.

In December, the FDA approved the drug for the two pain indications. Monday's ruling by the FDA enables Pfizer to conduct marketing campaigns identifying the drug as approved for seizure. Doctors are permitted by law to prescribe a drug for any disease as long as the FDA approves the drug for a single disease or condition, but companies can't market the drug for unapproved uses.

Pfizer's stock was up 20 cents to $27.88 Monday afternoon.