A retrospective poison center review of varenicline-exposed patients

Varenicline was approved by the Food and Drug Administration (FDA) as a prescription smoking cessation aid in May 2006. Varenicline is both a partial nicotine agonist and an antagonist. Recent reports by the Institute of Safe Medication Practices identified safety problems associated with varenicline use, and the FDA recently issued a boxed warning. These safety concerns regarding varenicline use prompted this study.

To characterize varenicline-exposed patients as reported to a poison control system.

We performed a retrospective search of the California Poison Control System electronic database from August 2006 through August 2008, using the term varenicline or Chantix. Cases matching these results were reviewed. All ages were included. Excluded were patients with coingestants and unknown outcomes. Clinical parameters and medical outcomes were extracted from the database.

Thirty-six cases met inclusion criteria and 17 cases were excluded, Ten cases involved nonpediatric patients; 9 cases involved patients less than 6 years old, which were defined as pediatric patients. The median duration of poison center follow-up for pediatric patients was 253 minutes; median duration of follow-up for nonpediatric patients with unintentional exposures was 28.5 minutes. The majority of exposures were unintentional and included all the pediatric patients and 6 nonpediatric patients who had unintentional medication errors. Gastrointestinal and neuropsychiatric adverse events were most frequently reported. The majority of these patients were managed at home. Among those evaluated at a healthcare facility, only 1 pediatric patient was admitted. Of the remaining patients, 1 nonpediatric patient reported a deliberate exposure and 3 nonpediatric patients experienced adverse effects at therapeutic doses. Median duration of follow-up for these patients was 308 minutes.

Patients exposed to varenicline in our study had favorable outcomes. Gastrointestinal and neuropsychiatric effects were the most commonly reported adverse events. A dose-response relationship could not be determined and triage criteria to a healthcare facility remain undetermined.