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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions Can cause serious neuropsychiatric events including depression and suicidal thoughts.
| FDA category | Animal |
| Breastfeeding | Excreted into animal milk (rat studies: 0.3-fold maternal plasma concentrations). No human M/P ratio available. Limited human data; potential for adverse effects on infant neurodevelopment due to nicotinic receptor modulation. Consider alternative therapy; if used, monitor infant for irritability, feeding difficulties. |
| Teratogenic Risk |
■ 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 |
["History of hypersensitivity to varenicline","Use in patients with end-stage renal disease not on dialysis (severe impairment)"]
| 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"] |
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| 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. |