1. Introduction
Varenicline is a partial nicotine receptor agonist used for smoking cessation. It works by binding to α4β2 nicotinic receptors, reducing nicotine cravings and withdrawal symptoms while also blocking the pleasurable effects of smoking.
2. Indications
- Smoking Cessation
- Off-Label Use:
- Alcohol dependence (investigational)
- Methamphetamine addiction (investigational)
3. Dosage
Adults:
- Standard Regimen:
- Days 1–3: 0.5 mg once daily
- Days 4–7: 0.5 mg twice daily
- Day 8 onward (up to 12 weeks): 1 mg twice daily
- Alternative Flexible Quit Approach:
- Start 0.5 mg daily, gradually increase to 1 mg twice daily over several weeks.
- Reduce smoking gradually before quitting completely within 12 weeks.
- Extended Treatment (for relapse prevention):
- 1 mg twice daily for another 12 weeks after initial course.
Renal Impairment:
- CrCl <30 mL/min: 0.5 mg once daily (max 0.5 mg twice daily).
- End-Stage Renal Disease (ESRD): Avoid use or use with caution.
Hepatic Impairment:
- No dose adjustment required.
Elderly (>65 years):
- Start at a lower dose in frail patients due to increased sensitivity.
4. Administration
- Take after meals with a full glass of water to reduce nausea.
- Begin treatment 1–2 weeks before the target quit date.
- Do not crush or chew tablets.
5. Forms Available
- Tablets: 0.5 mg, 1 mg
6. Side Effects
6.1 Common Side Effects:
- Nausea (most common)
- Insomnia
- Abnormal dreams
- Headache
6.2 Less Common Side Effects:
- Dry mouth
- Constipation
- Dizziness
6.3 Rare but Serious Side Effects:
- Neuropsychiatric Effects (Mood Changes, Suicidal Thoughts)
- Seizures (rare, but caution in seizure-prone patients)
- Cardiovascular Events (Possible increased risk in patients with pre-existing heart disease)
7. Warnings
- Neuropsychiatric Effects:
- Monitor for depression, agitation, suicidal ideation.
- Patients with a history of psychiatric illness should use with caution.
- Cardiovascular Risk:
- Use with caution in patients with unstable cardiovascular disease.
- Seizure Risk:
- May lower seizure threshold in susceptible individuals.
8. Precautions
- Patients with depression or anxiety: Use with caution; monitor mood changes.
- History of seizures: May increase seizure risk.
- Avoid alcohol or reduce intake: Increased risk of aggression and altered behaviour.
9. Interactions
- Nicotine Replacement Therapy (NRT): Increased risk of nausea and headaches; avoid combination unless necessary.
- Alcohol: May increase neuropsychiatric side effects.
- CYP450 Interactions: Minimal drug metabolism interactions.
10. Monitoring Parameters
- Mood and behaviour changes (depression, suicidal thoughts).
- Smoking cessation progress.
- Renal function in patients with kidney disease.
11. Use in Children
- Not recommended for individuals under 18 years (safety not established).
12. Use in Pregnancy
- Category C:
- Avoid unless absolutely necessary—risk to fetus unknown.
- Alternative smoking cessation methods (e.g., counselling, NRT) preferred.
13. Use in Elderly
- Safe, but monitor for increased dizziness or sedation.
14. Use in Kidney Disease
- CrCl <30 mL/min: Reduce dose.
- End-stage renal disease: Avoid use or use with caution.
15. Use in Liver Disease
- No dose adjustment required.
16. Patient Counselling Points
- Take after food with water to reduce nausea.
- Set a quit date 1–2 weeks after starting Varenicline.
- Be aware of mood changes—report severe depression or suicidal thoughts.
- Limit alcohol intake to avoid mood alterations.
- Continue treatment for up to 12 weeks—longer treatment reduces relapse.
17. Table of Brand Names, Manufacturer, and Prices in USD
Brand Name | Manufacturer | Strength/Dosage Form | Price (USD) |
---|---|---|---|
Chantix | Pfizer | 0.5 mg, 1 mg Tablets | $500 (30 tabs) |
Champix | Pfizer (Europe) | 0.5 mg, 1 mg Tablets | $450 (30 tabs) |
Generic Varenicline | Various | 0.5 mg, 1 mg Tablets | $200 (30 tabs) |
18. 15 FAQs (Frequently Asked Questions)
1. What is Varenicline used for?
It is used to help people quit smoking by reducing cravings and withdrawal symptoms.
2. How does Varenicline work?
It partially stimulates nicotine receptors, reducing cravings while blocking the effects of smoking.
3. How long does it take to work?
Start treatment 1–2 weeks before quitting. Full effects appear within 12 weeks.
4. Can I continue smoking while taking Varenicline?
Yes, but set a quit date within 1–2 weeks of starting.
5. Does Varenicline cause weight gain?
Smoking cessation itself may lead to weight gain, but Varenicline does not directly cause it.
6. Can I drink alcohol while taking Varenicline?
Limit alcohol intake—Varenicline may increase aggression and mood changes.
7. Can I stop taking Varenicline suddenly?
Yes, but gradual reduction may reduce withdrawal symptoms.
8. Can Varenicline cause vivid dreams?
Yes, abnormal dreams and insomnia are common side effects.
9. Does Varenicline interact with antidepressants?
No significant interactions, but monitor for mood changes.
10. Can I use nicotine patches with Varenicline?
Generally not recommended—may increase nausea and headaches.
11. Can Varenicline cause depression?
It may worsen mood in some patients; monitor for suicidal thoughts.
12. Is Varenicline better than nicotine patches?
Studies show higher quit rates with Varenicline compared to nicotine replacement therapy.
13. Can I take Varenicline long-term?
Yes, extended use (6 months) reduces relapse risk.
14. What happens if I miss a dose?
Take it as soon as remembered, but do not double the next dose.
15. How should I store Varenicline?
Store at room temperature, away from moisture.