A systematic review investigating the impact of modified varenicline regimens on smoking cessation

Introduction: The efficacy of varenicline as a smoking cessation aid is affected by commonly-occurring issues such as intolerable adverse events, cravings and withdrawal symptoms, and poor medication adherence. Improvement in quit rates may be achieved through tailoring doses relative to individual smokers’ behaviours, and previous experiences with smoking cessation medications. Aims: The aim of this review is to evaluate smoking cessation outcomes from published randomised controlled trials that have attempted to improve the efficacy and tolerability of varenicline through modifying its dosage regimen compared to placebo. Methods: A systematic search of the literature up to June 2016 was conducted to identify randomised controlled trials where varenicline was administered in a regimen not consistent with the current clinical guidelines. Outcome measures evaluated included continuous abstinence rates, changes in cravings, withdrawal symptoms, smoking behaviours, adverse event rates, and premature therapy discontinuations. Results: Ten randomised controlled trials, encompassing four different modifications to standard varenicline therapy, matched the eligibility criteria. Modifications such as the extended duration of therapy and the use of a flexible quit date were effective compared to placebo and have been implemented into some clinical guidelines, whereas other modifications do not appear to produce any benefit for smokers, or require further research to ascertain their suitability for clinical practice. Conclusions: Some varenicline therapy modifications may lead to improvements in efficacy and tolerability. Further research on the effect of modifications such as daily doses higher than 2mg, tapering doses, and the use of extended pre-quit varenicline may advance varenicline therapy outcomes