Smoking cessation can be achieved with or without assistance from healthcare professionals, or the use of medications. Some of these medications include the following.
Bupropion is FDA-approved and is marketed under the brand name Zyban. Bupropion is contraindicated in epilepsy, seizure disorder; anorexia/bulimia (eating disorders), patients’ use of antidepressant drugs (MAO inhibitors) within 14 days, patients undergoing abrupt discontinuation of ethanol or sedatives (including benzodiazepines such as Valium). Evidence from a systematic review suggests that antidepressants such as Bupropion and Nortriptyline help in long-term smoking cessation and that adverse events with both drugs are rarely serious enough to cause stopping of the medication. The evidence also points out that Bupropion is less effective than Varenicline however this needs to be further validated.
Nicotinic receptor partial agonists
A nicotinic agonist is a drug that mimics the action of acetylcholine (ACh) at nicotinic acetylcholine receptors (nAChRs).
Cytisine (Tabex) is a plant extract that has been in use since the 1960s in former Soviet-bloc countries. It was the first medication approved as an aid to smoking cessation, and has very few side effects in small doses.
Varenicline tartrate is a prescription drug marketed by Pfizer as Chantix in the U.S. (under FDA approval) and as Champix outside the U.S. Synthesized as an improvement upon cytisine, varenicline decreases the urge to smoke and reduces withdrawal symptoms. Two systematic reviews and meta-analyses supported by unrestricted funding from Pfizer, one in 2006 and one in 2009, found varenicline more effective than NRT or bupropion.
A table in the 2008 Guideline indicates that 2 mg/day of varenicline leads to the highest abstinence rate (33.2%) of any single therapy, while 1 mg/day leads to an abstinence rate of 25.4%. A 2011 Cochrane review of 15 studies (13 of which had been sponsored by Pfizer) found that varenicline was significantly superior to bupropion at one year but that varenicline and nicotine patches produced the same level of abstinence at 24 weeks.
A 2011 review of double-blind studies found that varenicline has increased risk of serious adverse cardiovascular events compared with placebo. Varenicline may cause neuropsychiatric side effects; for example, in 2008 the UK. Medicines and Healthcare products Regulatory Agency issued a warning about possible suicidal thoughts and suicidal behavior associated with varenicline.
Mimicking the MAO-A inhibiting effects of tobacco smoke
Moclobemide has been tested in heavy dependent smokers against placebo based on the theory that tobacco smoking could be a form of self medicating of major depression, and moclobemide could therefore help increase abstinence rates due to moclobemide mimicking the MAO-A inhibiting effects of tobacco smoke. Moclobemide was administered for 3 months and then stopped; at 6 months follow-up it was found those who had taken moclobemide for 3 months had a much higher successful quit rate than those in the placebo group. However, at 12 month follow-up the difference between the placebo group and the moclobemide group was no longer significant.
Medications in trials
Two other medications have been used in trials for smoking cessation, although they are not approved by the FDA for this purpose. They may be used under careful physician supervision if the first line medications are contraindicated for the patient.
Clonidine may reduce withdrawal symptoms and “approximately doubles abstinence rates when compared to a placebo,” but its side effects include dry mouth and sedation, and abruptly stopping the drug can cause high blood pressure and other side effects.
Nortriptyline, another antidepressant, has similar success rates to bupropion but has side effects including dry mouth and sedation.