Acetyl-L-carnitine (ALC) is not currently approved in the US for treating nerve pain, "but it is used widely for painful neuropathy in patients with diabetes and AIDS (news - web sites) in Europe," Dr. Anders A. F. Sima from Wayne State University School of Medicine in Detroit, noted in a telephone interview with Reuters Health.

The original two trials -- one conducted in Europe and the other in the US and Canada -- involved over 1000 patients with diabetic neuropathy who were given ALC (500 or 1000 milligrams taken three times a day) or an inactive placebo for 52 weeks.

Those tests showed ALC had no significant effect on nerve conduction velocity, an indicator of improvement in nerve damage, but when Sima's group looked into the data they found certain patients did benefit.

Apparently, ALC at the higher dose significantly alleviated pain in the 27 percent of patients who reported pain as "the most bothersome symptom" at the beginning of the studies, the team notes in the medical journal Diabetes Care.

"Pain is very common in patients with diabetic peripheral nerve diseases, occurring in 30 percent to 35 percent of patients," Sima said. "It is usually extremely bothersome for the patients and in extreme cases drives them to suicide. We found that ALC has a significant effect on pain."

The greatest reductions in pain were seen in patients who had had diabetic neuropathy for a short time. "This is an axiom that goes for any of these treatments in chronic disorders like this -- the earlier you can start treatment the better," Sima advised.

He added, ALC is "very tolerable."

Sima said his team is currently working with the US Food and Drug Administration (news - web sites) to get ALC formally approved for painful diabetic neuropathy.