CHANTIX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CHANTIX (CHANTIX).
Partial agonist at α4β2 nicotinic acetylcholine receptors; also full agonist at α7 nicotinic receptors. Reduces nicotine craving and withdrawal symptoms while blocking nicotine's reinforcing effects.
| Metabolism | Minimal hepatic metabolism; primarily renally excreted unchanged (glomerular filtration and active tubular secretion). Renal clearance accounts for >90% of elimination. Not metabolized by CYP enzymes. |
| Excretion | Renal: 81% unchanged, 8% as metabolites; Fecal: <10% (as metabolites); Biliary: minimal. |
| Half-life | Terminal elimination half-life is approximately 24 hours. Clinical context: Steady-state is achieved within 4 days; significant accumulation occurs in renal impairment (creatinine clearance <30 mL/min), requiring dose adjustment. |
| Protein binding | <20% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 7 L/kg. Clinical meaning: Extensive tissue distribution, with concentration in brain and other tissues exceeding plasma. |
| Bioavailability | Oral bioavailability is >90% after oral administration (capsule). |
| Onset of Action | Oral: Reduction in smoking urge and withdrawal symptoms typically begins within 1 week; maximal effect by week 5-6. |
| Duration of Action | Duration of action after stopping therapy: Receptor occupancy declines slowly due to long half-life; clinical effect persists for several days. Full therapeutic course is 12 weeks with possible additional 12-week maintenance. |
1 mg orally twice daily after starting a 1-week titration: days 1-3: 0.5 mg once daily; days 4-7: 0.5 mg twice daily; day 8 onward: 1 mg twice daily.
| Dosage form | TABLET |
| Renal impairment | For GFR <30 mL/min: maximum dose 0.5 mg twice daily. For ESRD on hemodialysis: maximum dose 0.5 mg once daily. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe impairment (Child-Pugh C); use with caution. |
| Pediatric use | Not approved for use in pediatric patients (safety and efficacy not established). |
| Geriatric use | No specific dose adjustment required, but consider renal function; use 0.5 mg twice daily initially for patients >65 years due to potential renal impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CHANTIX (CHANTIX).
| Breastfeeding | Excreted in animal milk; unknown in human milk. M/P ratio not established in humans. Caution advised due to potential for adverse effects in nursing infant (e.g., nausea, dizziness). Decide to discontinue breastfeeding or drug based on importance of drug to mother. |
| Teratogenic Risk | Pregnancy Category C. No adequate studies in pregnant women. In animal studies, fetal developmental toxicity (reduced fetal weight, increased incidence of skeletal variations) observed at exposures 50 times the human AUC. First trimester use may be associated with small risk of congenital malformations based on limited data; second and third trimester risks unknown. Use only if benefit outweighs potential fetal risk. |
■ FDA Black Box Warning
WARNING: SERIOUS NEUROPSYCHIATRIC EVENTS - Varenicline has been associated with serious neuropsychiatric adverse events including suicidal ideation, suicide attempt, completed suicide, hostility, agitation, depressed mood, and abnormal behavior. Patients should be monitored and advised to stop treatment if changes in mood or behavior occur.
| Serious Effects |
["Hypersensitivity to varenicline or any component of the formulation","End-stage renal disease (ESRD) on dialysis (not recommended due to lack of safety data)"]
| Precautions | ["Neuropsychiatric adverse events (including suicidal behavior and ideation, depression, hostility, agitation)","Seizures: Risk especially in patients with history of seizures or other factors lowering seizure threshold","Cardiovascular events: Increased risk of adverse cardiovascular events in patients with established cardiovascular disease","Angle-closure glaucoma: May precipitate acute angle-closure glaucoma in susceptible patients","Weight gain: Discontinuation may result in increased appetite and weight gain","Renal impairment: Dose adjustment required for patients with severe renal impairment (CrCl <30 mL/min)"] |
| Food/Dietary |
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| Fetal Monitoring | Monitor maternal blood pressure and heart rate; monitor for psychiatric symptoms (depression, suicidal ideation) common in pregnancy. Fetal assessment via ultrasound if exposure in first trimester; standard prenatal care otherwise. |
| Fertility Effects | No human data on fertility. In animal studies, no adverse effects on fertility or reproductive performance at exposures up to 50 times human AUC. |
| No specific food restrictions. Take with food to reduce gastrointestinal side effects such as nausea. Grapefruit juice has no known interaction. Avoid excessive alcohol consumption. |
| Clinical Pearls | Initiate CHANTIX (varenicline) 1 week before target quit date. Titrate dose over first week: 0.5 mg daily days 1-3, 0.5 mg twice daily days 4-7, then 1 mg twice daily. Monitor for neuropsychiatric symptoms, especially in patients with history of psychiatric disorders. Reduce dose in severe renal impairment (CrCl <30 mL/min) to 1 mg daily. Avoid use with alcohol due to increased risk of abnormal behavior or intoxication. May impair ability to drive or operate machinery. |
| Patient Advice | Take varenicline exactly as prescribed, starting one week before your planned quit date. · Take with food and a full glass of water to reduce nausea. · Do not skip doses; if you miss a dose, take it as soon as you remember unless it is close to the next dose. · Stop smoking completely on your quit date; continue taking varenicline for 12 weeks, then may continue for another 12 weeks if needed. · Report any unusual changes in mood, behavior, or thoughts of suicide immediately. · Avoid alcohol while taking this medication as it may increase effects. · Do not drive or operate heavy machinery until you know how varenicline affects you. · If you are pregnant, plan to become pregnant, or are breastfeeding, discuss risks with your doctor. |