Practical Tips for the Busy GP
From the Royal College of General Practitioners, May 2008
Varenicline is more effective than NRT or bupropion to aid in quitting smoking cigarettes. The main side effect is nausea.
Other methods to help patients quit are:
- NRT: the most widely used method. None of the formulations (patch, gum, lozenge, microtab, inhalator or spray) as been shown to be superior. Patients may need reassurance that the nicotine itself has been shown to have no harmful effects.
- Bupropion: is at least as effective as NRT. Side-effects include insomnia, headache, dry mouth and gastrointestinal symptoms. There is a one in 1000 chance of the patient having a fit, which should be taken into account for patients who drive or operate machinery as part of their occupation.
- You should advise patients that they will benefit far more from stopping smoking than merely reducing the number of cigarettes smoked. However, cutting down can be an effective part of a strategy to stop smoking, especially if combined with NRT with a cut down to stop approach (see Stead et al. in Further Reading).
- Patients who are considering quitting smoking need advice and support - smoking cessation clinics can be very effective.
Be aware of the risk of using varenicline in patients who have an underlying mental illness. Advise patients who are trying to stop smoking that they can develop symptoms of depression. Patients who develop suicidal thoughts while taking varenicline should stop their treatment and contact their doctor immediately.
How Varenicline works
Varenicline binds to a particular nicotinic acetylcholine receptor, where it acts as a partial agonist. By binding with this receptor, the drug limits craving and withdrawal symptoms; it also stops nicotine from binding and so reduces the rewarding and reinforcing effects of smoking.
Clinical evidence
Nicotine replacement is an effective additional component of smoking cessation strategies but evidence is limited as to any particular method of nicotine delivery having superior efficacy, when NICE considered the efficacy of varenicline, bupropion and nicotine replacement therapy (NRT) results showed that varenicline was better than placebo at helping patients to abstain from smoking.
How to use varenicline in practice
- Varenicline is contra-indicated in pregnancy; be cautious about using it in breast-feeding mothers and in patients with renal impairment.
- Smokers should set a date to stop smoking; treatment with varenicline should start one to two weeks beforehand.
- Start with 500 micrograms varenicline once daily for three days, then increase to 500 micrograms twice daily for four days, then 1 mg twice daily for 11 weeks (reduce to 500 micrograms twice daily if not tolerated).
- You can repeat the treatment in patients successfully quitting smoking cigarettes to reduce their risk of relapse.
- Avoid sudden withdrawal of the drug (this may cause a relapse, irritability, depression or insomnia) - taper the dose down instead.
- Smoking cessation therapies are more likely to work for patients who are also given additional advice and support. NICE recommends that varenicline should normally be provided with counselling and support, but if the support is refused or not available, you can still prescribe varenicline.
Side effects of Varenicline
The most common side effects of varenicline are:
- nausea (in up to 30%
- sleep disturbance (trouble sleeping, changes in dreaming)
- constipation
- flatus
- vomiting
The patient information leaflet warns that patients should be aware of the possible side effects of varenicline on driving - and not drive until they know whether varenicline affects their driving ability.
