UPDATE 1-US decides against additional Norvasc generics

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NEW YORK, April 18 (Reuters) - U.S. regulators have decided against approving generic versions of Pfizer Inc.'s (PFE.N: Quote, Profile, Research, Stock Buzz) Norvasc blood-pressure drug other than an already launched generic version made by Mylan Laboratories Inc. (MYL.N: Quote, Profile, Research, Stock Buzz)

The decision by the Food and Drug Administration came to light in a filing on Wednesday with the U.S. District Court for the District of Columbia.

Mylan launched its generic version of Norvasc last month. The generic drugmaker says it is entitled to 180 days as the lone generic Norvasc seller and has been seeking a temporary restraining order to bar other generic Norvasc approvals during that time.

Generic drugmakers can enjoy a cash infusion during such exclusivity periods, which federal lawmakers created as an incentive for companies to challenge weak patents. Norvasc had U.S. sales of about $2.7 billion last year and has been Pfizer's second-biggest seller.

Mylan launched generic versions of Norvasc after another court invalidated a Pfizer patent.

Canadian drugmaker Apotex had projected that no company would have the exclusivity period.

The FDA sought views on the issue before making its decision.

"FDA has decided not to approve (applications) other than Mylan's at this time," the court filing said.

Apotex and Teva Pharmaceutical Industries Ltd. (TEVA.O: Quote, Profile, Research, Stock Buzz) are among the companies with tentative U.S. approval for amlodipine besylate, the generic name for Norvasc.