A popular treatment for nicotine addiction can also cut cravings among crystal meth addicts, a US study suggests.

Crystal meth – the commonly used term for methamphetamine – is a cheap and addictive drug that has become a massive problem in the US in recent years. It increases alertness and creates sensations of euphoria in users by stimulating the generation of dopamine and norepinephrine – neurotransmitters within the regions of the brain responsible for feelings of pleasure.

Bupropion – the active chemical ingredient found in the nicotine addiction drug, Zyban, as well as the anti-depressant Wellbutrin – was found to reduce the drug-induced high experienced by methamphetamine users and also to lessen their urge to take the drug in response to visual cues, in a study by researchers at the University of California in Los Angeles (UCLA).

Twenty methamphetamine users were given either 150 milligrams of bupropion twice a day for a week, or a placebo.

Subjects were then injected with 30 milligrams of methamphetamine and asked to rate the high they experienced on a scale of 1 to 10, with 10 being the most intense imaginable. The users given doses of bupropion reported experiencing a significantly reduced high of, on average, 3 out of 10, compared to 5 out of 10 prior to the treatment.

"What we found, which was unexpected, was that it significantly reduced the euphoric effect," Thomas Newton at UCLA, who led the study, told New Scientist.

Video footage

Bupropion is thought to reduce cravings for nicotine by preventing it from getting into receptive parts of the brain. However, the researchers behind the UCLA study believe it may cut cravings for crystal meth in a different way. The drug inhibits the uptake of dopamine and norepinephrine by brain cells so they stay around longer. This may lessen cravings for crystal meth by decreasing the withdrawal effects normally experienced by users, when the neurotransmitters are taken up by neurons.

Crystal meth users given bupropion also reported far less of a craving in response to video footage of actors simulating drug use. Such visual cues would normally be expected to trigger a strong impulse to take the drug.

Newton admits there may be confounding factors involved. For example, he says several of the subjects of the trial smoked, and that smoking may act as a cue for methamphetamine use. So bupropion might have had an indirect impact by reducing the subjects craving for nicotine.

The group has begun second stage trials and hopes to work out precisely how bupropion may decrease craving among crystal meth users. "These findings may point the way towards medications with even greater potential to be helpful," Newton says.

Journal reference: Neuropsychopharmacology (advance online publication)