Low incidence of adverse events following varenicline initiation among opioid dependent smokers with comorbid psychiatric illness

Background: Most drug treatment patients smoke cigarettes, yet few data exist on the prevalence and outcomes of varenicline treatment among smokers with comorbid substance use and psychiatric disorders. Methods: We reviewed all patient charts of opioid-dependent smokers prescribed varenicline between May 2006 and December 2009 in two urban methadone clinics that also provide on-site medical and psychiatric care. We assessed prevalence, adverse events, and effectiveness of varenicline treatment in this cohort. Results: We identified 575 smokers among 690 patients (83.3%), and assessed 82 courses of varenicline treatment prescribed to 70 smokers. Both cardiovascular risk factors and psychiatric illness were highly prevalent among those prescribed varenicline: hypertension, 51%; hyperlipidemia, 23%; diabetes, 20%; depression, 53%; anxiety, 30%; psychotic disorders, 10%; bipolar disorder, 8.6%. Of 82 varenicline courses, nine (11%) were discontinued due to adverse events and two due to depressive symptoms. One patient initiated new psychiatric medications within six months of initiating varenicline, but did not discontinue varenicline. There were no reports of suicidal ideation, agitation prompting clinical intervention, or psychiatric hospitalization. There were no incident cardiac or vascular events within six months of varenicline prescription. Some (8.6%) varenicline-treated smokers quit smoking, and cessation was significantly associated with varenicline treatment duration. Conclusions: Despite substantial comorbidity, opioid-dependent smokers receiving integrated substance abuse, medical and psychiatric care had few documented adverse events with varenicline treatment. Methadone patients will likely experience little harm and a great deal of benefit from treatment with varenicline for smoking cessation.