(Corrects Pfizer plans in sixth paragraph in story published Oct. 5.)

Oct. 5 (Bloomberg) -- Pfizer Inc., the world’s biggest drugmaker, said it stopped a clinical trial of its epilepsy medicine Lyrica after results showed it was as effective as a stand-alone therapy for certain-types of seizures.

Lyrica generated more than $3 billion in sales last year for New York-based Pfizer, according to data collected by Bloomberg. The study aimed to show whether Lyrica worked without other drugs against partial seizures, the most common type experienced by people with the disorder.

Partial seizures are those limited to one side of the brain, according to the Epilepsy Foundation, based in Landover, Maryland. A monitoring committee recommended the tests end after interim results proved its efficacy, MacKay Jimeson, a company spokesman, said in an e-mail.

“Pfizer has accepted the recommendation and has stopped the study,” Jimeson said in an e-mail.

Lyrica is approved for use in combinations with other treatments in epilepsy, and for fibromyalgia, a condition involving pain in joints and muscles.

Updated results will be posted on clinicaltrials.gov by April of 2012, Jimeson said. In the meantime, Pfizer will continue to analyze the study.

--Editors: Andrew Pollack, Reg Gale.

To contact the reporter on this story: Pat Wechsler in New York at pwechsler@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net