New research shows that the best method to quit smoking may depend on how fast they metabolize the nicotine in their body.

“Normal” metabolizers of nicotine were significantly more likely to stay quit with the help of the drug varenicline (Chantix, manufactured by Pfizer) compared to the nicotine patch at the end of treatment and 6-months later, the new study published online this week in Lancet Respiratory Medicine found. “Slow” metabolizers, on the other hand, would most likely benefit from the nicotine patch, the authors suggest. Varenicline was just as effective as a nicotine patch at helping those people quit, but there were more overall side effects reported with the drug.