Cytisine increases the chances of quitting, although absolute quit rates were modest in two recent trials. Varenicline at standard dose increased the chances of successful long-term smoking cessation between two- and threefold compared with pharmacologically unassisted quit attempts. Lower dose regimens also conferred benefits for cessation, while reducing the incidence of adverse events. More participants quit successfully with varenicline than with bupropion. Two open-label trials of varenicline versus NRT suggested a modest benefit of varenicline but confidence intervals did not rule out equivalence. Limited evidence suggests that varenicline may have a role to play in relapse prevention. The main adverse effect of varenicline is nausea, but mostly at mild to moderate levels and tending to subside over time. Possible links with serious adverse events, including serious psychiatric or cardiovascular events, cannot be ruled out.

Future trials of cytisine may test extended regimens and more intensive behavioural support. There is a need for further trials of the efficacy of varenicline treatment extended beyond 12 weeks.
Dianicline, a novel α4β2 nicotinic acetylcholine receptor partial agonist, for smoking cessation: a randomized placebo-controlled clinical trial.
Dianicline is a α4β2 nicotinic acetylcholine receptor partial agonist, a class of drugs that includes varenicline and cytisine. Varenicline is efficacious for smoking cessation, while cytisine has not been studied systematically. The efficacy of dianicline has not been previously tested in an adequately powered study.
                In a randomized, double-blind, parallel group placebo-controlled trial, 602 generally healthy cigarette smokers were assigned to dianicline (n = 300) or placebo (n = 302) for 7 weeks followed by a 19-week off drug follow-up period.
                Exhaled carbon monoxide and cotinine-confirmed continuous abstinence rates for Weeks 4-7 were 24.0% for dianicline versus 20.5% for placebo (odds ratio 1.22; 95% CI, 0.83-1.80; p = .307). For Weeks 4-26, the abstinence rates were 16.7% for dianicline versus 13.9% for placebo (odds ratio 1.24; 95% CI, 0.79-1.93; p = .366). Craving for a cigarettes was reduced by dianicline compared with placebo after 7 weeks (p = .0175). Nicotine withdrawal symptoms measured by the Hughes and Hatsukami Minnesota Withdrawal Scale were lower for dianicline compared with placebo in the first 3 weeks of treatment during which time quit rates were also higher in the dianicline-treated group.
                Dianicline did not increase cigarette smoking abstinence rates beyond the initial phase of treatment. However, self-reported craving and nicotine withdrawal symptoms were reduced.