There are 3 first-line medications for smoking cessation i.e. nicotine 
replacement therapy (NRT), varenicline (a partial nicotine receptor agonist) and 
slow-release (SR) bupropion. All 3 agents approximately double 1-year quit rates 
when used for 3 months, although varenicline seems to be a little more 
efficacious than bupropion SR. An un-blinded study comparing varenicline with 
nicotine patches are analysed in details and it is concluded that the validity 
of that study is low regarding the relative efficacy of varenicline versus NRT. 
Depression and suicidal attempts have been reported with varenicline use but it 
is probably not induced by varenicline but by the quitting process per se. It is 
recommended that the first agent to be used in smoking cessation should be NRT 
as it is the best documented product with mild side effects. It might be optimal 
to combine the patch with either gum, inhaler, sublingual tablets or nasal 
spray. In subjects that have failed with NRT, varinicline should be the choice. 
Bupropion SR is preferred to subjects with depression or smokers who have failed 
with the previous two agents, due to the many contra-indications and side 
effects of bupropion SR. With one of the 3 agents combined with follow-up visits 
with counselling, one can expect a 1-year quit rate around 20-25%.