Pfizer Inc.’s (PFE) Lyrica, approved for use in fibromyalgia, didn’t work to control painful nerve damage from diabetes in one study, and the company halted a second trial in nerve-damaged HIV patients.

Lyrica, with sales (PFE) of $3.7 billion last year, didn’t significantly lessen the pain of diabetes patients with nerve damage who were switched to the drug after another treatment failed, New York-based Pfizer said. The company also halted a trial for HIV patients, after an interim analysis showed no difference between Lyrica and a placebo.

Even before today’s results investors and analysts had assumed Lyrica sales were near their peak, said Les Funtleyder, a portfolio manager at Miller Tabak & Co. whose fund owns Pfizer shares. The drug also is approved for use in pain after shingles, partial-onset seizures in adults with epilepsy, and diabetic nerve pain.

“The sense is Lyrica has gone about as far as it can go,” Funtleyder said. “Maybe it is a slight loss of upside, but we are not talking about a major hit.”

Pfizer, the world’s biggest drugmaker, declined less than 1 percent to $22.38 at the close of New York trading.

About 16 percent of people with diabetes develop pain and numbness from nerve damage caused by high blood-sugar levels, according to an April 2011 report from the American Academy of Neurology. About a third of HIV patients have nerve damage, and some of these people experience pain, according to the University of Chicago.

Pfizer said the trial in HIV patients wasn’t ended for safety reasons. In the diabetes study, the most common adverse events were fluid retention, dizziness, sleepiness and upper respiratory tract infection, which are known side effects of the drug, according to the company’s statement.

To contact the reporter on this story: Elizabeth Lopatto in New York at elopatto@bloomberg.net; Robert Langreth in New York at rlangreth@bloomberg.net

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