This study is the first, randomized,
placebo-controlled trial to evaluate the efficacy VC
compared with placebo in healthy smokers. VC
group tended to produce higher CAR and PAR
than placebo group at all follow-up periods. The
smokers’ odds at quitting smoking for VC were
about 2.0-3.0 times that for placebo from week
8 to week 24. This is consistent with results
of most current pharmacotherapies for smoking
cessation5)
. However, our findings did not reach
statistical significance due probably to the
relatively small number of participants to detect
the effect of at least 9.4 – 22.0% difference in CAR
or PAR between the VC and placebo groups. Large
scales trials with longer duration of treatment and
follow-up are needed to verify the efficacy of VC
versus placebo. One limitation of our study is that
the inclusion criterion was limited to the relatively
motivated healthy smokers, excluding smokers
with concurrent medical illnesses. This may
probably limit the generalizability of the results to
the majority of smokers in a typical primary care
population.
Few female smokers were enrolled in the study
and there is a significant difference in gender
between VC and placebo group. One might argue
that gender may affect the abstinence rate, but
several smoking cessation trials have indicated
that the abstinence rates were not significantly
different between male and female15,16)
. We
observed no serious adverse events and abnormal
laboratory data across two groups. The dropout
rate was higher in the placebo than VC. This
provides reassurance the tolerability of VC.
Craving reduction and dislike the taste and smell
of cigarette smoke were higher in VC compared
with placebo. From this result, we hypothesize VC
may decrease the reinforcing effect of cigarette
smoking. A translational opportunity for research
to discover the active compounds of VC as
potential use for smoking cessation, evaluate its
mechanism of action and potential as therapeutic
agents, develop alternative dosage formulations of
VC to enhance the convenience and adherence,
and replicate clinical trials with larger sample
size, optimal duration of treatment and longer
follow-up period are warranted. Lack of afford-
ability or health insurance to cover for smoking
cessation pharmacotherapy can reduce smoker
adherence, which may result in failure to quit
smoking. VC produces a saving in the cost
spent compared with other currently approved
pharmacotherapy for smoking cessation. This
could greatly lower the substantial costs of health
care for smokers who desire to quit smoking.