What to check before prescribing Chantix (varenicline)?

What to Check Before Prescribing Chantix (Varenicline)

Before prescribing varenicline, you must screen for history of psychiatric illness (especially depression, suicidal ideation, or psychosis), assess renal function to determine if dose adjustment is needed, rule out brain metastases or seizure history, and confirm the patient is not pregnant or breastfeeding. 1, 2, 3

Psychiatric History Assessment

• Screen all patients for current or past psychiatric disorders, including depression, anxiety, psychosis, bipolar disorder, and any history of suicidal thoughts or attempts 2, 3
• Ask specifically about symptoms during previous quit attempts, with or without medication, as this predicts risk 3
• While the EAGLES trial showed no significant increase in neuropsychiatric events compared to nicotine patches or placebo, monitoring remains essential as some patients have experienced new or worsening mental health problems, aggression, hostility, agitation, and suicidal thoughts 2
• Patients with active severe psychiatric illness require careful risk-benefit discussion, though varenicline is not absolutely contraindicated in stable psychiatric disease 2

Renal Function Evaluation

• Check serum creatinine and calculate creatinine clearance or eGFR before initiating therapy 4
• Renal function is the most clinically important factor affecting varenicline exposure, as the drug is almost exclusively excreted unchanged in urine 4
• Dose adjustment is required for severe renal impairment (CrCl <30 mL/min): reduce to 0.5 mg twice daily or 1 mg once daily 3, 4
• No dose adjustment needed for mild to moderate renal impairment 4

Neurological Contraindications

• Explicitly ask about and rule out brain metastases, particularly in cancer patients, as this is a contraindication due to seizure risk 2
• Document any history of seizures or seizure disorders, as seizures are a rare but significant risk with varenicline 2
• Patients with brain metastases or elevated seizure risk should not receive varenicline 2

Pregnancy and Breastfeeding Status

• Confirm pregnancy status in women of childbearing potential before prescribing 3
• Discuss risks of smoking versus potential risks of varenicline use during pregnancy 3
• If breastfeeding, counsel that the infant must be monitored for seizures and excessive vomiting/spitting up, as it is unknown if varenicline passes into breast milk 3

Allergy History

• Ask about any prior allergic reactions to varenicline, including serious skin reactions like Stevens-Johnson syndrome or erythema multiforme 3
• Previous serious allergic or skin reaction to varenicline is an absolute contraindication 3

Cardiovascular Assessment

• While earlier concerns existed, recent systematic reviews have not identified significant increases in serious cardiovascular adverse events with varenicline 2
• Document cardiovascular history but this is not a contraindication; the National Comprehensive Cancer Network considers varenicline to have a favorable risk/benefit ratio even in patients with cardiovascular disease 2

Current Medications and Other Cessation Aids

• Document all current medications, though varenicline has minimal drug interactions as it does not undergo significant CYP450 metabolism 4
• Ask specifically about concurrent use of other smoking cessation treatments (nicotine patches, bupropion), as combining varenicline with nicotine patches may increase nausea, vomiting, headache, and dizziness 3
• No dose adjustment needed for coadministration with warfarin, digoxin, cimetidine, or metformin 4

Common Pitfalls to Avoid

• Do not skip renal function testing—this is the single most important pharmacokinetic factor and directly determines dosing 4
• Do not dismiss psychiatric screening as optional—while serious events are rare, they can be severe, and baseline assessment allows for proper monitoring 2, 3
• Do not prescribe to patients with brain metastases—this is an explicit contraindication that is sometimes overlooked in cancer patients who would otherwise benefit from smoking cessation 2