Which of the following is a contraindication for using varenicline?

Varenicline is a smoking cessation medication that acts as a partial agonist at nicotinic receptors in the brain. One significant contraindication for its use is a history of seizures. This is because varenicline has been associated with an increased risk of seizures, especially in individuals with pre-existing conditions that might lower the seizure threshold.

Patients with a history of seizures may be at an elevated risk when using varenicline, making it unsuitable for this population. The prescriber should weigh the potential benefits of smoking cessation against the risks of seizures in these patients.

In contrast, while uncontrolled hypertension, liver disease, and non-smoker status may warrant caution or consideration when prescribing varenicline, they are not absolute contraindications. Uncontrolled hypertension could potentially lead to complications, but it is not a definitive barrier. Similarly, individuals with liver disease may require dose adjustments, but this condition alone does not preclude the use of the medication. Non-smokers would not typically be prescribed varenicline, but being a non-smoker does not make its use contraindicated if the person were to decide to quit smoking in the future.