CHAMPIX (Varenicline)

What Is CHAMPIX and What Is It Used For?

CHAMPIX (varenicline) is a prescription medication specifically developed for smoking cessation in adults. It contains the active substance varenicline, which belongs to a class of drugs known as nicotinic receptor partial agonists. CHAMPIX works by targeting the same receptors in the brain that nicotine binds to, helping to reduce both cravings and the pleasurable effects of smoking.

Smoking is the leading preventable cause of death worldwide, responsible for more than 8 million deaths annually according to the World Health Organization (WHO). Quitting smoking dramatically reduces the risk of heart disease, lung cancer, stroke, and chronic obstructive pulmonary disease (COPD). However, nicotine addiction makes quitting extremely difficult, with most unaided quit attempts resulting in relapse within days or weeks.

CHAMPIX was specifically developed to address the neurochemical basis of nicotine addiction. Varenicline binds with high affinity and selectivity to the alpha-4 beta-2 (α4β2) nicotinic acetylcholine receptors in the brain. These are the same receptors that nicotine from cigarettes activates to produce feelings of pleasure and reward. By binding to these receptors, varenicline has a dual mechanism of action:

• Partial agonist effect: Varenicline partially stimulates nicotine receptors, producing a moderate level of dopamine release. This helps alleviate the cravings and withdrawal symptoms that occur when you stop smoking, such as irritability, difficulty concentrating, restlessness, and depressed mood.
• Antagonist effect: By occupying the nicotine receptors, varenicline simultaneously blocks nicotine from binding. This means that if you do smoke while taking CHAMPIX, the nicotine from cigarettes cannot fully activate the receptors, so you experience less pleasure and reinforcement from smoking.

Clinical trials have consistently demonstrated that CHAMPIX is one of the most effective pharmacological aids for smoking cessation. The landmark EAGLES trial (Evaluating Adverse Events in a Global Smoking Cessation Study), published in The Lancet in 2016, compared varenicline to nicotine replacement therapy (NRT), bupropion, and placebo in over 8,000 smokers. The study found that varenicline had the highest continuous abstinence rates at both 12 weeks and 24 weeks of follow-up.

CHAMPIX is indicated exclusively for use in adults aged 18 years and older. It is not recommended for children or adolescents, as efficacy has not been established in these age groups. The medication is available under various brand names globally: CHAMPIX in Europe, the UK, and many other countries, and Chantix in the United States (though the Chantix brand was discontinued in the US market in 2021 due to the presence of a nitrosamine impurity, with generic formulations subsequently becoming available). Generic varenicline is also manufactured by companies including Teva and Glenmark.

What Should You Know Before Taking CHAMPIX?

Before starting CHAMPIX, inform your doctor about your complete medical history, including any psychiatric conditions, kidney problems, heart disease, or history of seizures. CHAMPIX should not be used during pregnancy or breastfeeding. Key warnings include the potential for neuropsychiatric effects such as mood changes, depression, and suicidal thoughts, as well as serious allergic reactions and cardiovascular symptoms.

Contraindications

CHAMPIX should not be taken if you are allergic (hypersensitive) to varenicline or any of the other ingredients in the tablets. The inactive ingredients include microcrystalline cellulose, anhydrous calcium hydrogen phosphate, croscarmellose sodium, colloidal anhydrous silica, and magnesium stearate. The film coating contains hypromellos, titanium dioxide (E171), macrogol 400, and triacetin, with the 1 mg tablets also containing indigo carmine aluminium lake (E132).

If you have experienced a severe allergic reaction to varenicline previously – including symptoms such as facial swelling, lip or tongue swelling, difficulty breathing, or skin rash – you must not take CHAMPIX again. Inform your healthcare provider of any previous reactions to this medication.

Warnings and Precautions

It is important to understand that quitting smoking itself, with or without medication, can trigger various psychological and physiological changes. Nicotine withdrawal is associated with increased irritability, depressed mood, anxiety, sleep disturbances, difficulty concentrating, and restlessness. Some individuals who have attempted to quit smoking, with or without treatment, have experienced worsening of pre-existing psychiatric conditions.

If you have a history of psychiatric illness, including depression, bipolar disorder, schizophrenia, or anxiety disorders, discuss this thoroughly with your doctor before starting CHAMPIX. While the EAGLES trial did not find a significant increase in neuropsychiatric adverse events with varenicline compared to placebo even in patients with psychiatric conditions, ongoing monitoring is recommended for all patients.

Cardiovascular symptoms: New or worsening cardiovascular symptoms have been reported, primarily in patients who already have cardiovascular disease. Tell your doctor if your symptoms change during treatment with CHAMPIX. Seek emergency medical help immediately if you experience symptoms of a heart attack (chest pain, pain radiating to the arm or jaw, shortness of breath, cold sweat) or stroke (sudden numbness or weakness on one side of the body, confusion, severe headache, vision problems).

Seizures: Inform your doctor if you have a history of seizures or epilepsy before starting treatment. Some patients have reported seizures during CHAMPIX treatment. If you experience a seizure, stop taking CHAMPIX and contact your healthcare provider immediately.

Hypersensitivity and skin reactions: Stop taking CHAMPIX and seek immediate medical attention if you experience signs of a severe allergic reaction, including swelling of the face, lips, tongue, palate, throat, or body, and/or difficulty breathing or wheezing (angioedema). Potentially life-threatening skin rashes, including Stevens-Johnson syndrome (SJS) and erythema multiforme, have been reported. If you develop a rash, skin peeling, or blistering, stop CHAMPIX immediately and seek emergency medical care.

Pregnancy and Breastfeeding

You should not take CHAMPIX if you are pregnant. There is insufficient clinical data on the use of varenicline in pregnant women, and the potential risks to the developing fetus are not fully established. If you are planning to become pregnant, talk to your healthcare provider about alternative approaches to smoking cessation. Non-pharmacological methods such as behavioral counseling, cognitive behavioral therapy, and motivational interviewing are preferred first-line options during pregnancy.

Although it has not been specifically studied, varenicline may pass into breast milk. You should consult your doctor before taking CHAMPIX if you are breastfeeding. The decision whether to discontinue breastfeeding or to discontinue CHAMPIX therapy should take into account the benefit of breastfeeding for the child and the benefit of therapy for the mother.

Driving and Operating Machinery

CHAMPIX may cause dizziness, drowsiness, and transient loss of consciousness. You should not drive, operate complex machinery, or engage in other potentially hazardous activities until you know how this medication affects you. If you experience any of these symptoms, avoid activities that require alertness and discuss with your healthcare provider.

How Does CHAMPIX Interact with Other Drugs?

CHAMPIX has relatively few direct drug interactions because it undergoes minimal hepatic metabolism. However, the act of quitting smoking can significantly alter the metabolism of other medications. Smoking induces certain liver enzymes (particularly CYP1A2), so when you stop smoking, the levels of medications metabolized by these enzymes may increase, potentially requiring dose adjustments.

Tell your doctor or pharmacist about all medications you are currently taking, have recently taken, or might take. This includes prescription drugs, over-the-counter medications, vitamins, and herbal supplements. Although varenicline itself has limited drug-drug interactions due to its predominantly renal excretion (more than 90% is excreted unchanged in the urine), several important interactions should be noted.

Interactions Related to Smoking Cessation

The most important “interactions” are actually physiological changes caused by quitting smoking rather than direct interactions with varenicline. Cigarette smoke contains polycyclic aromatic hydrocarbons that induce the hepatic enzyme CYP1A2. When you stop smoking, this enzyme induction reverses, potentially increasing the blood levels of medications metabolized by CYP1A2. This may require dose adjustments for the following medications:

Direct Drug Interactions

Cimetidine: If you have severe kidney disease, you should avoid taking cimetidine (a medication used for stomach problems) at the same time as CHAMPIX. Cimetidine reduces the renal clearance of varenicline, which can lead to elevated blood levels of CHAMPIX. In patients with normal kidney function, this interaction is not clinically significant.

Other smoking cessation treatments: Talk to your doctor before using CHAMPIX in combination with other smoking cessation therapies such as nicotine replacement therapy (patches, gum, lozenges) or bupropion. While some studies have investigated combination therapy, the safety and efficacy of these combinations are not fully established, and the use of CHAMPIX with nicotine replacement therapy may increase the incidence of nausea, headache, and other adverse effects.

Alcohol

There have been post-marketing reports of increased intoxicating effects of alcohol in patients taking CHAMPIX. Some individuals have experienced unusual or aggressive behavior, or memory loss when drinking alcohol during treatment. While it is not definitively known whether CHAMPIX actually increases the toxic effects of alcohol, it is advisable to limit your alcohol consumption until you understand how CHAMPIX affects you. If you notice any unusual reactions to alcohol, inform your healthcare provider.

What Is the Correct Dosage of CHAMPIX?

The standard CHAMPIX dosing regimen involves a one-week titration period starting at 0.5 mg once daily, increasing to 0.5 mg twice daily, then to the maintenance dose of 1 mg twice daily from day 8 onwards. Treatment typically lasts 12 weeks, with the option to extend for an additional 12 weeks. Always take CHAMPIX exactly as prescribed by your doctor.

Before starting CHAMPIX, you should set a target quit date during the second week of treatment (between Day 8 and Day 14). Alternatively, if you prefer a more flexible approach, you can choose your own target quit date within 5 weeks of starting treatment. Write this date down on the medication packaging as a reminder. The gradual dose titration in the first week helps minimize side effects, particularly nausea.

Adults – Standard Dosing Schedule

Take CHAMPIX tablets whole with a full glass of water. They can be taken with or without food, although taking them with food may help reduce nausea. Try to take your doses at approximately the same time each morning and evening.

If you have successfully quit smoking after 12 weeks of treatment, your doctor may recommend an additional 12-week course of CHAMPIX (1 mg twice daily) to help prevent relapse. This extended treatment has been shown in studies to reduce relapse rates significantly compared to stopping treatment at 12 weeks.

Gradual Reduction Approach

If you are unable or unwilling to set a fixed quit date, you can use a gradual reduction approach. With this method, you reduce your smoking during the first 12 weeks of treatment while working toward complete cessation by the end of this period. You should then continue taking CHAMPIX 1 mg twice daily for an additional 12 weeks, resulting in a total treatment duration of 24 weeks. Studies have shown this flexible approach can be effective for smokers who are not ready for abrupt cessation.

Patients with Kidney Problems

If you have kidney problems, discuss this with your doctor before starting CHAMPIX. For patients with mild to moderate renal impairment, no dose adjustment is typically needed. However, for patients with severe renal impairment (creatinine clearance less than 30 mL/min), the recommended dose is 1 mg once daily. Your doctor may start you at 0.5 mg once daily for the first three days before increasing to 1 mg once daily.

Children and Adolescents

CHAMPIX is not recommended for use in children and adolescents under 18 years of age. Clinical studies in this age group have not demonstrated efficacy, and the safety profile in younger patients has not been adequately established.

Elderly Patients

No dose adjustment is necessary for elderly patients. However, elderly patients are more likely to have reduced kidney function, which should be taken into account. Your doctor will consider your overall health and kidney function when prescribing CHAMPIX.

Missed Dose

If you forget to take a dose, take it as soon as you remember. However, if your next dose is due within 3–4 hours, skip the missed dose and take your next dose at the regular time. Do not take a double dose to make up for a forgotten dose. Maintaining a consistent dosing schedule at the same times each day can help prevent missed doses.

Overdose

If you accidentally take more CHAMPIX than prescribed, contact your doctor immediately or go to the nearest hospital emergency department. Bring the tablet packaging with you. In clinical trials, the most commonly reported symptoms of overdose were nausea and vomiting. There is no specific antidote for varenicline overdose, and treatment is supportive.

What Are the Side Effects of CHAMPIX?

Like all medications, CHAMPIX can cause side effects, although not everyone experiences them. The most commonly reported side effects are nausea (affecting more than 1 in 10 users), abnormal dreams, insomnia, and headache. Serious but rare side effects include neuropsychiatric events (depression, suicidal thoughts), cardiovascular events, seizures, and severe skin reactions. Report any concerning symptoms to your doctor immediately.

It is important to note that quitting smoking itself, whether or not you are using CHAMPIX, can cause various symptoms. These include mood changes (feeling depressed, irritable, frustrated, or anxious), insomnia, difficulty concentrating, decreased heart rate, and increased appetite or weight gain. These effects are related to nicotine withdrawal rather than the medication.

Unknown frequency (reported post-marketing): Transient loss of consciousness has been reported. If this occurs, do not drive or operate machinery.

How Should You Store CHAMPIX?

Store CHAMPIX out of the sight and reach of children. For blister packs, store at temperatures not exceeding 30°C (86°F). Bottles have no special storage requirements. Do not use CHAMPIX after the expiry date printed on the packaging.

Proper storage of CHAMPIX is essential to maintain the effectiveness and safety of the medication. Follow these guidelines to ensure your tablets remain in optimal condition throughout the treatment course:

• Temperature: For blister packs, store at or below 30°C (86°F). For bottles, no special temperature requirements apply, though room temperature storage is advisable.
• Location: Keep the medication out of the sight and reach of children. Store in a dry place away from direct sunlight and moisture.
• Expiry date: Do not use CHAMPIX after the expiry date (EXP) shown on the packaging. The expiry date refers to the last day of that month.
• Disposal: Do not dispose of unused or expired medications in household waste or via the sewage system. Return unused medicines to your pharmacy for proper disposal to help protect the environment.

CHAMPIX is available in several packaging configurations, including starter packs (containing both 0.5 mg white tablets and 1 mg light blue tablets for the titration phase) and continuation packs (containing only 1 mg tablets for the maintenance phase). The white 0.5 mg tablets are capsule-shaped and marked “Pfizer” and “CHX 0.5”. The light blue 1 mg tablets are capsule-shaped and marked “Pfizer” and “CHX 1.0”.

What Does CHAMPIX Contain?

Each CHAMPIX tablet contains varenicline as the active ingredient (available as 0.5 mg or 1 mg strengths, in the form of varenicline tartrate). The tablets also contain several inactive ingredients (excipients) used for manufacturing, coating, and stability purposes.

Active Ingredient

The active substance in CHAMPIX is varenicline, present as varenicline tartrate. Each 0.5 mg tablet contains 0.5 mg of varenicline (as tartrate), and each 1 mg tablet contains 1 mg of varenicline (as tartrate). Varenicline tartrate is a white to off-white crystalline powder that is soluble in water.

Inactive Ingredients (Excipients)

Tablet core (both strengths):

• Microcrystalline cellulose – a bulking agent
• Anhydrous calcium hydrogen phosphate – a diluent
• Croscarmellose sodium – a disintegrant (this is the source of the trace sodium content)
• Colloidal anhydrous silica – a glidant
• Magnesium stearate – a lubricant

Film coating (0.5 mg white tablets):

• Hypromellos, titanium dioxide (E171), macrogol 400, triacetin

Film coating (1 mg light blue tablets):

• Hypromellos, titanium dioxide (E171), macrogol 400, indigo carmine aluminium lake (E132), triacetin

The difference in color between the two strengths is due to the presence of indigo carmine aluminium lake (E132) in the 1 mg tablet coating, which gives it its characteristic light blue appearance. Both tablet strengths are capsule-shaped (modified capsule form) and are film-coated for ease of swallowing.