Experiences with the use of varenicline in daily practice in the Netherlands: a prospective, observational cohort study.

Background: Although a concise overview of adverse drug reactions (ADRs) to varenicline is available, little is known about the use of varenicline in daily practice and time-related information about ADRs.

Objective: The aim of this study was to gain insight in the safety and use of varenicline in daily practice.

Methods: A prospective, observational, non-interventional cohort study was performed. The study population was defined as first-time users recruited through participating pharmacies between 1 December 2008 and 31 March 2012. Patients could sign up for the study on a dedicated website. Web-based questionnaires were sent after 1, 2 and 6 weeks, 3 months and 4 months after patients started to use varenicline. Questions were asked about drug use and ADRs. Information about the ADR, its seriousness and the action taken when experiencing an ADR was gathered.

Results: A total of 1,418 patients signed up for the study. The response rates for the various questionnaires varied from 31.3 to 62.5 %. At least one ADR was reported by 58.8 % of the patients. The most frequently reported ADRs were nausea (30.8 %), abdominal pain (11.2 %) and abnormal dreaming (10.4 %). Most patients did not stop taking varenicline when they experienced these ADRs. The median latency times for ADRs reported more than 50 times were 3-7 days, with an exception for depressed mood, which had a latency time of 10 days.

Conclusion: This prospective cohort study has given insight into latency time and action taken with varenicline when ADRs occur during treatment with varenicline in daily practice. It confirms the ADR pattern detected prior to marketing of the drug.