April 5 (UPI) -- Metformin, a drug commonly used to treat people with type 2 diabetes, might help curb nicotine withdrawal without side effects, according to a study of mice.
Researchers at Johns Hopkins University and the University of Pennsylvania found the inexpensive drug was effective in treating mice induced with a nicotine addiction. Their findings were published Thursday in the Proceedings of the National Academy of Sciences of the United States of America.
Metformin, marketed as Glucophage and other trade names, was discovered in 1918 After it was discontinued due to toxicity and the increased availability of insulin, the drug was found to be less potent than other glucose-lowering biguanides and was subsequently reintroduced in France in 1957 and the United States in 1995.
Common therapies -- such as nicotine replacement, an antidepressant and a medication used to mediate the pleasurable feelings smokers associate with cigarettes -- already exist to help people kick their nicotine habits.
But none directly treats nicotine withdrawal symptoms, according to Dr. Sangwon Kim, of the Johns Hopkins University School of Medicine's Division of Endocrinology, Diabetes and Metabolism.
"In cigarette smokers, nicotine has been shown to reduce anxiety," the researchers wrote. "Given the lack of studies on the effects of nicotine in nonsmokers, it is unclear whether nicotine reduces anxiety in the absence of withdrawal; however, numerous studies in rodent models have demonstrated dose-dependent anxiolytic effects of nicotine in drug-naive subjects.
"There is considerable evidence that withdrawal-associated anxiety contributes to poor adherence to smoking cessation treatments as well as relapse rates, with many smokers experiencing anxiety symptoms during acute abstinence periods."
The researchers wanted to determine whether metformin can stimulate an enzyme, known as AMP-activated protein kinase, or AMPK, to fight symptoms of nicotine withdrawal. The AMPK pathway is active during regular nicotine use, but not during withdrawal stages
"This is the first-ever study to examine AMPK's relation to nicotine dependence," Kim said in a press release.
When nicotine-treated mice were given metformin for one week, they displayed no anxiety or other negative effects of withdrawal. The drug use did not affect weight, food consumption or glucose levels in the mice.
If clinical trials in humans confirm the findings in mice, metfomin has "real potential" as a smoking cessation aid, Kim said