Tailoring Varenicline to Individual Needs (TVIN Study) (TVIN)

Varenicline is a partial nicotinic agonist which acts on alpha4 beta2 nicotinic receptors. It is presumed to alleviate withdrawal discomfort, but also to diminish rewarding effects of cigarettes. The standard varenicline dosing has been formulated to avoid adverse reactions (primarily nausea) in sensitive clients. The downside of this cautious approach is that a substantial proportion of clients may be under-dosed. A blanket dose increase would inevitably increase the incidence of side effects, but it is likely that tailoring varenicline dosing to clients' needs would be safe and may further increase varenicline's efficacy. This study will recruit 200 smokers who report little change to their enjoyment of cigarettes and no nausea, during the first week of varenicline use. These smokers will be randomised to receive the standard dose plus placebo or plus individualised varenicline dose up to 5mg, titrated over the next week prior to their target quit day. Urges to smoke, and other withdrawal symptoms, experienced during the study period will be compared between groups to see if the tailored therapy may be useful.

Participants will increase varenicline dose by 0.5 mg twice daily every three days to a maximum of 2.5 mg twice daily. This increased dose will be continued for 3-weeks before being reduced to the standard dose of 1.0 mg twice daily.

Participants will increase placebo dose by 0.5 mg twice daily every three days to a maximum of 2.5 mg twice daily. This increased dose will be continued for 3-weeks before being reduced to the standard varenicline dose of 1.0 mg twice daily.

All participants will receive the standard dose of Varenicline (14 weeks): 0.5 mg once daily for days 1-3, 0.5 mg twice daily for days 4-7, and then a continuation dose of 1.0 mg twice daily. In addition to this participants will use an tailored varenicline/placebo dose up to maximum of 2.5 mg twice daily for 3 weeks.

Identification of the number of people with no effect of varenicline (as measured on a self reported questionnaire) prior to the target quit date

The change of withdrawal symptoms from target quit day over the first 4-weeks of abstinence assessed by the Mood and Physical Symptoms Scale

Profile of all adverse effects (as measured by a self reported questionnaire) reported up to 12-weeks post quitting

Inclusion Criteria: Smoker seeking treatment Aged 18 and over Consenting to take part Report little or no change in enjoyment of cigarettes and/or nausea Exclusion Criteria: Pregnant or breastfeeding Have severe kidney disease Have severe heart problems Have a current psychiatric illness Are unable to fill in questionnaires in English Have an allergy to varenicline Are currently involved in another clinical trial

Hajek P, McRobbie H, Myers Smith K, Phillips A, Cornwall D, Dhanji AR. Increasing varenicline dose in smokers who do not respond to the standard dosage: a randomized clinical trial. JAMA Intern Med. 2015 Feb;175(2):266-71. doi: 10.1001/jamainternmed.2014.6916. Erratum In: JAMA Intern Med. 2016 Jan;176(1):143.