Pharmacotherapy, particularly when supported by behavioural counselling, improves long-term quit rates compared with no treatment or placebo.  Although access to pharmacotherapies varies in different countries where it is available it can be an important adjunct to smoking cessation advice and counselling for nicotine-dependent smokers. Smokers of 10 or more cigarettes a day who are ready to stop should be encouraged to use pharmacologial support as a cessation aid.
Three types of pharmacotherapy have been approved to aid smokers attempting to quit: nicotine replacement therapy, bupropion and varenicline.
Nicotine replacement therapy
Nicotine replacement therapy (NRT) works by reducing the severity of tobacco withdrawal symptoms by replacing nicotine in the blood. This reduces withdrawal symptoms associated with smoking cessation, helping users resist the urge to smoke cigarettes. NRT is available in a number of different forms, including chewing gum, skin patches (different doses), nose spray, inhalers and lozenges/tablets though not all forms have been approved in all countries. NRT increase the odds of quitting about 1.5 to 2 fold.
General principles of using NRT
There is little evidence that any one formulation is consistently better than any other - the choice may be determined by the patient's preferenceNicotine Gum
Around 17% of smokers who use nicotine gum remain abstinent 12 months later.
- Side effects associated with nicotine gum include gastrointestinal disturbances and jaw pain. Patients with dentures may be unable to use nicotine gum
- Instruct your patient to 'chew and park'. (Chew gum until taste is strong, then rest gum between gum and cheek, chew again when taste has faded) 
- Absorption of nicotine from the gum may be impaired when taken concurrently with coffee and some acidic drinks
Nicotine patches are available in various shapes and sizes, can be worn for 16-hours or 24-hours and deliver between 7 mg and 22 mg of nicotine, depending on the patch worn. High-dose nicotine patches (44 mg) are more effective in heavier smokers
- Patches are designed to provide a slow, consistent release of nicotine throughout the day. Link The blood nicotine concentrations of NRT
- Common side effects with patches include skin sensitivity and irritation.
Nicotine nasal sprays
Nicotine nasal spray and a nicotine inhaler nearly double a smoker's odds of quitting.
Nicotine sublingual tablets and lozenges
Cessation rates of around 17% after 12 months are associated with nicotine tablets.
- Nicotine tablets deliver 2-mg or 4-mg dosages of nicotine over a 30-minute period.
- Side effects include: burning sensations in the mouth, sore throat, coughing, dry lips, and mouth ulcers.
Bupropion is an atypical antidepressant that reduces the urge to smoke and the severity of tobacco withdrawal symptoms. The quit attempt is generally initiated one week after starting pharmacotherapy. Bupropion doubles the odds of smoking cessation (average quit rate of 19% versus 10% in the control groups). Bupropion has been shown to be effective in a range of populations including smokers with chronic diseases such as cardiovascular disease and chronic obstructive pulmonary disease. While there is insufficient evidence that adding bupropion to NRT provides an additional long-term benefit it is reasonable to combine them if maximal therapy with either has not been effective.Bupropion is typically prescribed as bupropion SR 150 mg twice daily (using a reduced dose of 150mg daily in the elderly or those with liver or renal disease daily). Bupropion almost doubles the quit rate compared to placebo at 6- or 12-month follow-up visits.
- Between 7% and 12% of smokers do not tolerate the side effects and discontinue the medication.
- The most common side effects are insomnia (up to 30%), dry mouth (10-15%), headache (10%), nausea (10%), constipation (10%), and agitation (5-10%)
- About 1 in 1,000 patients will have a seizure on bupropion, which is therefore contraindicated in people with, with a past history of, or at risk of seizures.
- Bupriopion is also contraindicated in people with anorexia nervosa, bulimia, bipolar disorder or severe liver disease.
- Bupriopion interacts with a number of common drugs including some antidepressants, antipsychoitics and anti-arrhythmics.
Nortriptyline is a tricyclic antidepressant which has been used to treat depression since 1963. It is not licensed for use in smoking cessation. However, in dosages of 75mg daily (less in elderly or adolescents) it has been shown to increase cessation rates from 7% to 17% compared to placebo (NNT=10). and may be an option in countries where the cost of licensed smoking cessation drugs is prohibitive. Recognised side-effects include sedation, dry mouth, lightheadedness and risks of cardiac arrhythmia, and recent myocardial infarction is a contra-indication. A stopping date should be agreed during the second week of treatment: usually seven to twelve weeks, with no need to step down the dose.
Varenicline, a selective alpha4beta2 nicotinic acetylcholine receptor partial agonist, is believed to work by reducing the severity of the smoker's urge to smoke and alleviating many withdrawal symptoms from nicotine. If a person smokes a cigarette while receiving treatment, the medicine may have the potential to diminish the sense of satisfaction associated with smoking. Varenicline has been shown to be significantly more efficacious than placebo for long-term abstinence, with an average quit rate of 21.4% compared to 8% for controls.One-year cessation rates are the same for bupropion and NRT. But varenicline is associated with higher quit rates than bupropion in comparative studies.
- The most common side effects with varenicline include: nausea (up to 30%), insomnia, (14%), abnormal dreams (13%), headache (13%), constipation (9%), gas (6%) and vomiting (5%). There is no danger of seizures.
- Varenicline should not be used in pregnancy:
- Dosage: A week before the quit date take 0.5 mg daily for 3 days, 0.5 mg twice a day for 4 days, then from the quit date take 1 mg twice a day for 12 weeks.
- Varenicline is a new drug, and it is too early fully to assess side effects. Patients on this medication should be monitored carefully.