VARENICLINE
Clinical safety rating: safe
Animal studies have demonstrated safety
Partial agonist at α4β2 nicotinic acetylcholine receptors; full agonist at α7 nicotinic receptors. Reduces nicotine craving and withdrawal symptoms by binding to receptors and blocking nicotine binding.
| Metabolism | Metabolized primarily by glucuronidation via UGT2B7 and oxidation via CYP2A6 (minor). Minimal metabolism; 92% excreted unchanged in urine. |
| Excretion | Renal: 92% unchanged in urine; fecal: <2%; hepatic metabolism: minimal. |
| Half-life | Terminal elimination half-life: 24 hours; steady-state reached within 4 days. |
| Protein binding | Low: <20%; primarily to albumin. |
| Volume of Distribution | Vd: 6.6 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: >90% absorbed. |
| Onset of Action | Oral: 2-3 days for initial reduction in craving; full effect by 4 weeks. |
| Duration of Action | Oral: 12 weeks for smoking cessation; may extend to 24 weeks for prevention. |
1 mg orally twice daily after 1-week titration: 0.5 mg once daily for days 1-3, 0.5 mg twice daily for days 4-7, then 1 mg twice daily. Reduce to 0.5 mg twice daily if intolerance.
| Dosage form | TABLET |
| Renal impairment | CrCl < 30 mL/min: maximum 0.5 mg twice daily; CrCl < 15 mL/min or hemodialysis: not recommended. |
| Liver impairment | No dose adjustment required for mild-to-moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C); use with caution. |
| Pediatric use | Safety and efficacy not established in patients <18 years. Not approved for pediatric use. |
| Geriatric use | No routine dose adjustment based on age alone; consider renal function. Elderly patients may be more sensitive to adverse effects (e.g., nausea, insomnia). |
| 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.
| Breastfeeding | Unknown if excreted in human milk. M/P ratio not determined. Breastfeeding not recommended due to potential adverse effects on infant neurodevelopment and gastrointestinal tract. |
| Teratogenic Risk | Pregnancy Category C. First trimester: Limited human data; animal studies show reduced fetal weight and skeletal variations at supratherapeutic doses. Second/third trimester: No controlled studies; potential risk of nicotinic acetylcholine receptor modulation affecting fetal neurodevelopment. |
■ FDA Black Box Warning
Serious neuropsychiatric events including suicidal thoughts/behavior, hostility, agitation, depressed mood, and unusual changes in behavior have been reported. Risk is increased in patients with psychiatric disorders at baseline.
| Common Effects | Nausea |
| Serious Effects |
["Hypersensitivity to varenicline or any component","End-stage renal disease (CrCl < 30 mL/min) (relative contraindication due to accumulation)"]
| Precautions | ["Neuropsychiatric symptoms: monitor for changes in mood/behavior","Cardiovascular events: increased risk of myocardial infarction and stroke in patients with cardiovascular disease","Angioedema and hypersensitivity reactions","Seizures: increased risk in patients with history of seizures","Interaction with alcohol: may increase alcohol effects"] |
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| Fetal Monitoring |
| Monitor maternal blood pressure and heart rate due to potential cardiovascular effects. Assess for nausea, vomiting, and neuropsychiatric symptoms. No specific fetal monitoring required but consider growth ultrasound if exposure during pregnancy. |
| Fertility Effects | No human data. Animal studies show no impairment of fertility at clinically relevant doses. Potential for reduced spermatogenesis at high doses in male rats; relevance unknown. |