Cytisine for Smoking Cessation

February 25, 2026 updated by: Bernard Le Foll, Centre for Addiction and Mental Health

Cytisine: Testing Its Potential as a Therapeutic Strategy for Smoking Cessation Among People With Concurrent Alcohol Use Disorder

The goal of this clinical trial is to evaluate the safety and effectiveness of cytisine as a smoking cessation treatment in individuals with concurrent alcohol use disorder.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Ontario
      • Toronto, Ontario, Canada, M5S 2S1
        • Center for Addiction and Mental Health

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Aged 18-65 years;
  • Have TUD assessed by structured clinical interview for DSM-5;
  • Have past year AUD (active) assessed by structured clinical interview for DSM-5;
  • Report daily cigarette consumption in past month and expired carbon monoxide (CO) measurement ≥10ppm at screening;
  • Have Fagerstrom Test of Nicotine Dependence (FTND55) score ≥4;
  • Have motivation to quit within 30 days i.e. Contemplation Ladder56 score ≥7;
  • Be willing and able to comply with all study procedural and assessment demands;
  • Be able to provide voluntary written informed consent.

Exclusion Criteria:

  • Report prolonged smoking abstinence in the past month preceding screening;
  • Be using other smoking cessation aids
  • Enrolled in another smoking cessation program
  • Be pregnant, breastfeeding, or intending to become pregnant or breastfeed;
  • Exhibit suicidal thoughts or behavior in the past month;
  • Enrolled in another study which would interfere with study procedures or represent a potential risk to the participant
  • Have a serious unstable psychiatric or medical condition preventing participation in the trial. This includes some forms of schizophrenia, ischemic heart disease, heart failure, arterial hypertension (systolic BP above 150; diastolic BP above 100), cerebrovascular diseases, occlusion of blood vessels, kidney and/or liver disease, hyperthyroidism, ulcer, diabetes, Chromaffin tumours of the adrenal medulla, and gastroesophageal reflux disease (GERD)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Cytisine

Cytisine will be given as 1.5 mg tablet formulations for 25 days.

The following treatment schedule will be followed:

  • Days 1 to 3: 1.5 mg taken every 2 hours (6 pills (9 mg)/day)
  • Days 4 to 12: 1.5 mg taken every 2.5 hours (5 pills (7.5 mg)/day)
  • Days 13 to 16: 1.5 mg taken every 3 hours (4 pills (6 mg)/day)
  • Days 17 to 20: Taper down to 1 tablet every 5 hours (3 pills (4.5 mg)/day)
  • Days 21 to 25: Taper down to 1-2 tablets daily (1.5-3 mg/day)
Drug: Cytisine
Cytisine is a nicotinic acetylcholine receptor partial agonist and is a natural health product approved by Health Canada. Cytisine has been used for a long time in Europe for smoking cessation.
Placebo Comparator: Placebo
Placebo will be given following the same schedule as the Cytisine Arm.
Other: Placebo
A placebo identical in appearance to cytisine will be used

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Frequency and type of adverse events
Time Frame: Total duration of trial (24 weeks)
To assess the tolerability of cytisine
Total duration of trial (24 weeks)
Rate of retention in the trial: number of sessions completed for each participant and number ofparticipants who withdraw
Time Frame: Total duration of trial (24 weeks)
To assess the tolerability of cytisine
Total duration of trial (24 weeks)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Point-prevalence abstinence
Time Frame: Week 2 and week 4
Complete abstinence ("not even a puff") during a designated time period (7 days) prior to assessment. This will be measured at each assessment point (e.g., 2 and 4wk).
Week 2 and week 4
Repeated point-prevalence abstinence
Time Frame: Throughout study completion, up to 24 weeks.
Point-prevalence abstinence at each consecutive assessment point.
Throughout study completion, up to 24 weeks.
Prolonged abstinence
Time Frame: This period will end at the end of treatment (day 25) or at final follow-up.
Complete abstinence ("not even a puff") after an initial grace period; also known as sustained abstinence.
This period will end at the end of treatment (day 25) or at final follow-up.
Prolonged abstinence with lapses
Time Frame: This period will end at the end of treatment (day 25) or at final follow-up.
Prolonged abstinence after a grace period, but some smoking is allowed (e.g., no more than 5 cigarettes; fewer than seven consecutive days of smoking).
This period will end at the end of treatment (day 25) or at final follow-up.
Continuous Abstinence
Time Frame: Throughout study completion, up to 24 weeks.
Complete abstinence ("not even a puff") beginning on the TQD (i.e., with no grace period) and lasting until the assessment from target quit date (week 2) to end of treatment (day 25) and at final follow up.
Throughout study completion, up to 24 weeks.
Physical dependence to Nicotine in Participants
Time Frame: Throughout study duration (24 weeks)
The Fagerstrom Test for Nicotine Dependence (FTND) will be used to assess physical dependence in participants.
Throughout study duration (24 weeks)
Nicotine Withdrawal Symptoms in Participants
Time Frame: Throughout study duration (24 weeks)
The Minnesota Nicotine Withdrawal Scale (MNWS) will be used to assess nicotine withdrawal symptoms.
Throughout study duration (24 weeks)
Nicotine Craving in Participants
Time Frame: Throughout study duration (24 weeks)
Tiffany Questionnaire of Smoking Urges (QSU) will be used to assess nicotine craving.
Throughout study duration (24 weeks)

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Tertiary Endpoints to evaluate the impact of cytisine vs. placebo on anxiety.
Time Frame: Throughout study duration (24 weeks)
Anxiety will be measured through the General Anxiety Disorder-7 (GAD-7) questionnaire.
Throughout study duration (24 weeks)
Tertiary Endpoints to evaluate the impact of cytisine vs. placebo on mood.
Time Frame: Throughout study duration (24 weeks)
Mood will be measured by the Patient Health Questionnaire-9 (PHQ-9).
Throughout study duration (24 weeks)
Tertiary Endpoints to evaluate the impact of cytisine vs. placebo on Quality of Life.
Time Frame: Throughout study duration (24 weeks)
Quality of Life will be measured through the WHO Disability Assessment Schedule (WHODAS).
Throughout study duration (24 weeks)
Tertiary Endpoints to evaluate the impact of cytisine vs. placebo on drinking by collecting the number of drinking days in participants.
Time Frame: Throughout study duration (24 weeks)
Number of drinking days and drinks per day/drinking day will be collected.
Throughout study duration (24 weeks)
Tertiary Endpoints to evaluate the impact of cytisine vs. placebo on drinking by measuring the proportion of heavy drinking days in participants.
Time Frame: Throughout study duration (24 weeks)
Percent of heavy drinking days (5+/4+ males/females)/very heavy drinking days (10+/8+ males/females) per week and per month will be collected.
Throughout study duration (24 weeks)
Tertiary Endpoints to evaluate the impact of cytisine vs. placebo on drinking by measuring the proportion of participants without heavy drinking days.
Time Frame: Throughout study duration (24 weeks)
Percent of subjects who are abstinent, percent of subjects with no heavy drinking days and percent of days abstinent will be collected.
Throughout study duration (24 weeks)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Centre for Addiction and Mental Health

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Bernard Le Foll, The Centre for Addiction and Mental Health

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 8, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 12, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 12, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 24, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 6, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 15, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 27, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 25, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 054-2022

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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