The Effect of Varenicline on D2/D3 Receptor Binding in Smokers
This study will evaluate effects of treatment with varenicline, a smoking cessation drug, on the dopaminergic system by using Positron Emission Tomography (PET) imaging with new radioligand, [11C]-(+)-PHNO. The investigators primary hypothesis is that chronic varenicline administration will increase dopamine (DA) receptors levels ([11C](+)PHNO) within the human brain.
|Study Design:||Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
|Official Title:||Investigating the Effects of Varenicline on D2/3 Receptor Binding in Brain of Tobacco-smokers: a PET/[11C](+)PHNO Study|
- [11C]-(+)-PHNO DRD2/3 binding potential (BPND) [ Time Frame: 10 days ] [ Designated as safety issue: No ]The effects of chronic administration of varenicline (standard dose run up protocol to 2 mg per day for 10 days) vs. baseline on [11C]-(+)-PHNO binding in human brain of tobacco smokers (12 hours abstinent).
- Relationship between ability to quit smoking and changes in DRD2/3 [ Time Frame: 6 months ] [ Designated as safety issue: No ]Relationship between clinical ratings of abstinence and cravings and DRD2/3 normalization after 10-day course of varenicline administration.
|Study Start Date:||September 2012|
|Study Completion Date:||January 2014|
|Primary Completion Date:||January 2014 (Final data collection date for primary outcome measure)|
Varenicline will be used at the same dosage regimen as used for smoking cessation, i.e. 0.5mg once daily for days 1-3, 0.5mg twice daily for days 4-7 followed by 1mg twice daily. The total duration of Varenicline treatment will be three months.
Varenicline will be administered as prescribed: 0.5 mg for the first 3 days then 1 mg for the next 7 days and 2 mg after that. A quit date will be chosen at 11 days after starting Varenicline. Varenicline will be given for 3 months.
Other Name: Champix
Subjects will undergo a pre-treatment PET and MRI scans for baseline [11C](+)PHNO measures on Day 1. Subjects will subsequently be provided an initial 2-week supply of study medications (varenicline) and directions for use. Any adverse events, compliance to medication and smoking patterns will be noted during these two weeks. Varenicline will be used at the same dosage regimen as used for smoking cessation. After subjects go through a post-treatment PET and MRI scans on Day 10, they will be instructed to set up a quit date. There will then be follow-up visits every 2 weeks for the duration of the medication phase (3 months total) and a visit at 6 months follow-up.
|Centre for Addiction and Mental Health|
|Toronto, Ontario, Canada|
|Principal Investigator:||Bernard Le Foll, MD, PhD||Centre for Addiction and Mental Health|