The first head-to-head comparison of a number of stop-smoking aids available on the market has found that nicotine patches combined with the occasional nicotine lozenge works best of all.

The study, published in the Archives of Psychiatry, was the first large, randomized controlled trial to compare the success rates of the stop-smoking aids. Until now, most studies on "smoking cessation" tools simply compared them to a placebo, not against one another.

Researchers from the University of Wisconsin Center for Tobacco Research and Intervention wanted to know which worked better: the antidepressant medication often prescribed for smokers wanting to quit, called bupropion (sold as Zyban or Wellbutrin), or less expensive nicotine patches, lozenges, or a combination.

They had more than 1,500 smokers, who were ready to quit, compare five real treatments and one fake one:

• nicotine lozenge alone,
• nicotine patch alone,
• bupropion alone,
• patch plus nicotine lozenge,
• bupropion plus nicotine lozenge
• placebo

Because bupropion takes a while to become effective, that treatment began one week before a designated quit date and continued for eight weeks. All the other treatments were taken for eight to 12 weeks after the quit date.

There were no serious side effects reported from any of the treatment options. The participants were also offered six individual counselling sessions.

Six months after the treatments were begun, only those smokers who combined the nicotine patch and lozenges were more successful in quitting than those taking placebo. Of them, 40 per cent reported they were no longer smoking six months out.

Smokers using the patch-lozenge combo were also more likely to have quit at seven days and tended to have other more positive outcomes, such as a longer period of time before relapsing.

In addition, the combination, along with the patch alone, were most effective at helping people achieve at least one day of abstinence from smoking, an important stepping stone to successful quitting.

It's thought that the patch-lozenge combo worked because it supplied a steady supply of nicotine while the lozenges gave users a "boost" of nicotine when they had an extra craving.

While nicotine lozenges were chosen for the study, the researchers say similar results would likely be found with other "adjuvant" nicotine replacements such as nicotine gum, nasal spray or an inhaler.

"The key seems to be that an ad libitum, or as needed, agent must be paired with the patch; simply using higher patch doses does not seem to augment outcomes to the same degree," the authors write.

This research was funded by the U.S. National Institutes of Health. Medication was provided free by drug maker GlaxoSmithKline. Several of the study authors reported financial ties to different pharmaceutical companies.