VARENICLINE TARTRATE
Clinical safety rating: safe
No significant drug interactions Can cause serious neuropsychiatric events including depression and suicidal thoughts.
Partial agonist at α4β2 nicotinic acetylcholine receptors, reducing nicotine craving and withdrawal symptoms by stimulating moderate dopamine release and blocking nicotine binding.
| Metabolism | Minimal metabolism (<10%): primarily excreted unchanged in urine with minor contributions from CYP2A6, glucuronidation, and N-formylation. |
| Excretion | Renal excretion of unchanged drug accounts for approximately 92% of elimination, with renal clearance exceeding glomerular filtration rate, indicating active tubular secretion; fecal excretion accounts for ~7% (1% as unchanged drug, rest as metabolites), and biliary excretion is negligible. |
| Half-life | Terminal elimination half-life is approximately 24 hours (range 20–29 hours) in healthy adults; steady-state is reached within 4 days; half-life is prolonged in severe renal impairment (CrCl <30 mL/min) to ~40 hours. |
| Protein binding | Approximately 20% bound to plasma proteins (primarily albumin); binding is concentration-independent. |
| Volume of Distribution | Volume of distribution (Vd) is approximately 3–4 L/kg, suggesting extensive extravascular distribution and tissue binding; clinical meaning: drug distributes widely into tissues, consistent with its CNS activity. |
| Bioavailability | Oral bioavailability is approximately 100% (nearly complete absorption) with no significant first-pass metabolism; food does not affect absorption. |
| Onset of Action | Oral administration: Onset of clinical effect (reduction in nicotine withdrawal symptoms and smoking urge) occurs within 1–2 hours after first dose, with peak effect after several days of dosing. |
| Duration of Action | Duration of action: 24 hours with once-daily dosing after a 1-week titration; clinical efficacy in maintaining abstinence persists throughout treatment (12–24 weeks) and may extend beyond cessation; rebound effect unlikely. |
| Molecular Weight | 361.35 |
Initial: 0.5 mg orally once daily on days 1-3, then 0.5 mg twice daily on days 4-7, then 1 mg twice daily starting day 8; target dose: 1 mg twice daily; route: oral; frequency: twice daily after initial titration.
| Dosage form | TABLET |
| Renal impairment | CrCl 30-50 mL/min: No dosage adjustment required. CrCl <30 mL/min (or on hemodialysis): Initial dose 0.5 mg once daily; may increase to 0.5 mg twice daily if tolerated and needed; maximum 0.5 mg twice daily. |
| Liver impairment | Child-Pugh Class A or B: No dose adjustment necessary. Child-Pugh Class C: Use with caution; no specific dose adjustment recommended, but exposure may be increased. |
| Pediatric use | Not approved for use in pediatric patients; safety and efficacy not established. No weight-based dosing guidelines available. |
| Geriatric use | No specific dose adjustment required solely for age; consider renal function in dose selection as elderly patients may have reduced creatinine clearance; follow renal adjustment guidelines. |
| 1st trimester | Insufficient human data; animal studies show fetal harm. Avoid use during first trimester unless benefit outweighs risk. |
| 2nd trimester | No adequate studies; potential fetal risk. Use only if clearly needed. |
| 3rd trimester | No adequate studies; potential fetal risk. Use only if clearly needed. |
Clinical note
No significant drug interactions Can cause serious neuropsychiatric events including depression and suicidal thoughts.
| FDA category | Animal |
| Placental transfer | Likely crosses placenta based on molecular weight and lipid solubility; no human data. |
| Breastfeeding | Excreted in animal milk; unknown human excretion. Risk of adverse effects in infant. Use caution; consider alternative therapies or discontinue breastfeeding. |
■ FDA Black Box Warning
Serious neuropsychiatric events including suicidality, depression, and hostility have been reported, particularly in patients with pre-existing psychiatric disorders.
| Common Effects | Nausea |
| Serious Effects |
Hypersensitivity to varenicline or any component
| Precautions | Neuropsychiatric symptoms requiring monitoring, Cardiovascular events in patients with cardiovascular disease, Seizures in those with seizure history, Angioedema and hypersensitivity reactions, Accidental injury potential due to dizziness/somnolence, Concomitant alcohol use may increase intoxication effects |
| Food/Dietary | No significant food interactions. Taking with food may reduce nausea. Avoid excessive alcohol consumption as it may increase the risk of neuropsychiatric events. |
Loading safety data…
| Lactation Rating | L3 |
| Teratogenic Risk | Pregnancy Category C. Animal studies (rats, rabbits) at exposures up to 0.5 and 23 times the MRHD showed decreased fetal weight, increased incidence of external and visceral malformations (e.g., umbilical hernia, undescended testis) and skeletal variations (e.g., incomplete ossification, wavy ribs) at doses causing maternal toxicity. First trimester: unknown risk, insufficient human data. Second/third trimester: limited human data; theoretical risk of reduced fetal nicotinic receptor development. Avoid unless benefit outweighs risk. |
| Fetal Monitoring | Monitor fetal growth (serial ultrasound) due to animal data showing decreased fetal weight. Assess for congenital anomalies with detailed anatomy scan. Maternal monitoring: hepatic function (rare ALT elevations), psychiatric symptoms (depression, suicidal ideation), nausea/vomiting (common, may require antiemetics). Monitor blood pressure and heart rate. |
| Fertility Effects | In animal studies (rats), no effects on male or female fertility at exposures up to 50 times MRHD. In humans, no well-controlled studies; potential for reduced fertility due to improved smoking cessation (smoking is known to reduce fertility). No direct adverse effect expected. |
| Clinical Pearls | Start varenicline 1 week before target quit date; titrate dose over first week to reduce nausea. Dose adjustment required in severe renal impairment (CrCl <30 mL/min). Avoid use in patients with history of suicidality or severe psychiatric instability. Monitor for neuropsychiatric symptoms. Contraindicated with bupropion due to increased seizure risk. |
| Patient Advice | Take varenicline after eating with a full glass of water to reduce nausea. · Choose a quit date about 1 week after starting the medication. · Do not skip doses; if you smoke after the quit date, continue taking varenicline. · Report any mood changes, agitation, or suicidal thoughts to your doctor immediately. · Varenicline may cause drowsiness; avoid driving until you know how it affects you. · Do not use this medication if you are pregnant or breastfeeding. · Store at room temperature away from moisture and heat. |