Among cigarette smokers, combining the smoking cessation medications varenicline and bupropion, compared with varenicline alone, resulted in higher smoking abstinence rates for one outcome but not the other at three and six months; rates were similar at one year, according to a Mayo Clinic study published this month in JAMA.
"We were interested in seeing if combining different medications together can improve the ability of patients to quit over and above single drug therapy," says lead author Jon Ebbert, M.D., Mayo Clinic Nicotine Dependence Center. "What we found was an increase in quit rates, and the increase in quit rates was particularly strong in heavier and more dependent smokers."
The study authors looked at the efficacy of combining the medications varenicline and bupropion SR (sustained-release) for smoking cessation, compared with varenicline alone (monotherapy). In addition, the research team analyzed data based on participants' smoking rate and level of nicotine dependence.
Cigarette smokers were randomized to 12 weeks of varenicline and bupropion SR or varenicline and placebo with follow-up through 52 weeks. The primary outcome was smoking abstinence rates at week 12, defined as prolonged abstinence (no smoking from two weeks after the target quit date) and seven-day point-prevalence abstinence (no smoking past seven days). Outcomes were confirmed with an exhaled breath test for carbon monoxide.
Combination therapy was associated with significantly higher prolonged smoking abstinence rates at 12 (53 percent vs. 43.2 percent) and 26 weeks (36.6 percent vs. 27.6 percent) compared with varenicline alone. No significant differences were observed between the two groups at any time point for seven-day point-prevalence smoking abstinence. Anxiety was reported more commonly with combination therapy than with varenicline monotherapy (7.2 percent vs. 3.1 percent), as were depressive symptoms (3.6 percent vs. 0.8 percent).
Additional analyses revealed that the beneficial effects of combination therapy were stronger in heavier and more dependent smokers.
"For lighter smokers, using varenicline alone is just as effective as using both medications together," says Dr. Ebbert. "But, if you're a heavy smoker, you really should consider using combination therapy to increase your success of quitting."