How does it work?

Champix tablets contain the active ingredient varenicline, which is a medicine used to help people who are addicted to nicotine to give up smoking. It acts in the brain, but is not the same as nicotine replacement therapy.

Varenicline is a type of medicine called a nicotinic acetylcholine receptor partial agonist. This means that it acts on the same receptors in the brain as nicotine.

Varenicline works by stimulating the nicotinic receptors in the brain. This produces an effect that relieves the craving and withdrawal symptoms you can get when you stop smoking.

At the same time, varenicline blocks nicotine from acting on the nicotinic receptors. This prevents any nicotine inhaled in tobacco smoke from having a rewarding and enjoyable effect.

What is it used for?

• Aid for giving up smoking in adults.

How do I take it?

You should set a date on which you will stop smoking and start taking this medicine one to two weeks beforehand. This is because the medicine needs time to start working.

The dose is increased gradually in the first week of treatment (follow the instructions given by your doctor or pharmacist) and the medicine should then be taken twice a day for 12 weeks (once a day if you have kidney problems). If you have successfully managed to stop smoking at the end of 12 weeks, your doctor may offer you a further 12 week course of treatment.

The tablets should be swallowed whole with a drink of water. They can be taken with or without food.

You should seek help and support as much as possible while giving up smoking, even while taking this medicine, as this will increase your chance of success. Your doctor, practice nurse or local pharmacist can all provide this support.

Warning!

• This medicine might make you feel dizzy or sleepy and so could impair your ability to perform potentially hazardous tasks such as driving or operating machinery. You should avoid driving or operating machinery until you know how this medicine affects you and are sure that it won’t affect your ability to perform such activities safely.
• There have been reports of suicidal thoughts or behaviour in people taking this medicine to help them give up smoking. It is very difficult to know if this is due to the medicine, as giving up smoking itself can make people depressed, especially if they already have a mental health problem, and depression is associated with suicidal thoughts. However, not all people experiencing depression and suicidal thoughts while taking this medicine had a previous history of psychiatric illness, or had stopped smoking. For this reason, if you begin to feel agitated or depressed, experience any changes in your behaviour or have thoughts about suicide or harming yourself during treatment with this medicine, you should stop taking it and consult your doctor immediately.
• Some people may find that when they stop taking this medicine their urge to smoke returns. They may also feel irritable, depressed or have difficulty sleeping. To avoid this, your doctor may consider reducing your dose slowly when you finish treatment with this medicine, rather than stopping it abruptly. Discuss this with your doctor.

Use with caution in

• People with decreased kidney function.
• People with disease involving the heart and blood vessels (cardiovascular disease).
• People with a history of psychiatric illness, eg depression, schizophrenia, bipolar disorder.
• Epilepsy (this medicine has not been studied in people with epilepsy).

Not to be used in

• Pregnancy.
• This medicine is not recommended for children and adolescents under 18 years of age, as there is no information regarding its safety and efficacy in this age group.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

• The safety of this medicine for use during pregnancy has not been established. It should not be used by pregnant women. Seek further medical advice from your doctor.
• It is not known if this medicine passes into breast milk, but it is possible that it may. As a result, it is not recommended for mothers who are breastfeeding. If you have been unable to give up smoking using any other method, you should discuss with your doctor whether it may be appropriate to stop breastfeeding in order to try this medicine. This will depend on factors such as the importance of breastfeeding to the child, how much smoke the child is being exposed to and how likely this medicine is to help you stop smoking. Seek medical advice from your doctor.

Side effects

Giving up smoking with or without treatment can cause various symptoms. These include changes in mood (such as feeling depressed, irritable, frustrated or anxious), difficulty sleeping or concentrating, decreased heart rate and increased appetite or weight gain.

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with using this medicine to help give up smoking. It is not known if these side effects are a result of using the medicine, or a result of giving up smoking. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

The safety and benefits of taking this medicine in combination with other medicines for stopping smoking (for example bupropion (Zyban) or nicotine replacement therapy) have not been studied. Other smoking cessation medicines are therefore not recommended while you are taking this one. Using nicotine replacement therapy (NRT) in combination with this medicine has been shown to increase nausea, headache, vomiting, dizziness, indigestion, fatigue and drops in blood pressure compared to NRT alone.

If you have severe kidney problems you should not take cimetidine in combination with this medicine, as it may increase the amount of varenicline in the blood.

The components of tobacco smoke can cause certain medicines, for example those listed below, to be removed from the body faster than normal. When you stop smoking, they are removed slower, so their blood levels may increase. This means that if you are taking any of these medicines, your doses may need adjusting after you stop smoking:

• clozapine
• dextropropoxyphene
• flecainide
• fluvoxamine
• olanzapine
• pentazocine
• phenylbutazone
• some benzodiazepines, eg oxazepam
• some beta-blockers, eg propranolol
• tacrine
• theophylline
• tricyclic antidepressants, such as imipramine