Za Pharmacy
Drugs, Supplies and Delivery
Varenicline (Champix)
Varenicline, marketed under the brand name Champix, is a prescription medication specifically designed to aid smoking cessation. It works by targeting nicotine receptors in the brain, reducing cravings and withdrawal symptoms while diminishing the pleasurable effects of smoking. This article provides a detailed overview of varenicline, referencing authoritative sources such as the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology. We will explore its mechanism of action, uses, dosage, side effects, precautions, drug interactions, and generic names in pharmacy.
Varenicline’s unique mechanism involves dual action on nicotine receptors:
- Partial Agonism at α4β2 Nicotinic Receptors:
- Binds to the α4β2 subtype of nAChRs, the same receptors activated by nicotine (Lippincott).
- Provides mild stimulation to reduce cravings and withdrawal symptoms, mimicking nicotine’s effects at a lower intensity (BNF).
- Nicotine Receptor Blockade:
- Prevents nicotine from fully binding to these receptors, reducing the reinforcing effects of smoking (Lange).
- Dopamine Modulation:
- Partially activates dopamine release in the brain’s reward pathways, alleviating withdrawal without the peak effects caused by nicotine (Lippincott).
Varenicline is indicated for:
- Smoking Cessation:
- Helps adults quit smoking by reducing cravings and withdrawal symptoms.
- Recommended for use alongside counseling and behavioral interventions (BNF).
- Long-Term Abstinence:
- Shown to improve long-term success rates compared to placebo and other therapies like nicotine replacement (Lange).
Varenicline requires a titration schedule to minimize side effects. Always follow the prescribing physician’s instructions.
Standard Dosage:
- Days 1–3: 0.5 mg once daily.
- Days 4–7: 0.5 mg twice daily.
- Day 8 onward: 1 mg twice daily (BNF).
Administration Tips:
- Take tablets with food and a full glass of water to reduce nausea.
- Begin treatment 1–2 weeks before the target quit date.
- Total treatment duration is typically 12–24 weeks.
Varenicline is generally well-tolerated but may cause:
Common:
- Nausea (30% of users, often mild and transient).
- Insomnia or abnormal dreams.
- Headache, constipation, or flatulence.
Serious but Rare:
- Neuropsychiatric Effects: Mood changes, depression, suicidal ideation (requires immediate medical attention) (BNF).
- Cardiovascular Events: Increased risk in patients with pre-existing heart disease (Lippincott).
- Seizures: Rare but reported in patients with seizure history (Lange).
Before using varenicline, inform your healthcare provider if you have:
- A history of psychiatric disorders (e.g., depression, schizophrenia).
- Cardiovascular disease or kidney impairment.
- Seizure disorders or epilepsy.
- Allergies to varenicline or formulation components.
Special Populations:
- Pregnancy: Avoid unless benefits outweigh risks (limited data; BNF Category: Not formally classified).
- Breastfeeding: Safety not established; avoid.
- Renal Impairment: Dose adjustments required for severe impairment (e.g., 1 mg once daily).
Varenicline interacts with few medications but caution is advised with:
- CNS-Acting Drugs:
- May enhance effects of alcohol or sedatives, causing dizziness or impaired judgment (BNF).
- Nicotine Replacement Therapy (NRT):
- Concurrent use is not recommended due to increased nausea and headache risk (Lippincott).
- Renally Excreted Drugs:
- Drugs like cimetidine may reduce varenicline clearance, requiring dose adjustments (Lange).
Generic Names in Pharmacy
- Varenicline tartrate (active ingredient)
- Common brand name: Champix®
