Champix has come under scrutiny over reports it causes suicidal feelings.
The Medicines and Healthcare Products Regulatory Agency says it is "closely" monitoring the drug after almost 3,000 reports of adverse reactions.
This shows that the investments that we are making in helping smokers to quit are having a positive impact
So far there have been more than 200 reports of suicidal thoughts in patients taking Champix.
And more than 350 reports of depression, although these have mainly involved patients who had an underlying psychiatric illness.
The drug is unusual as it both stimulates and blocks specific nicotinic receptors in the brain.
By stimulating the receptor it is thought to mimic the effects of nicotine to reduce cravings.
At the same time, it partially blocks the receptor preventing nicotine from binding to it, resulting in a weaker response in people who give in to temptation and have a cigarette.
Trials suggested around 44percent of smokers give up after taking the drug twice a day for 12 weeks, compared with 18percent of those given a placebo and 30 percent of those taking another major anti-smoking drug, bupropion.
Health minister Ann Keen said she was delighted with the increase in people successfully quitting smoking.
"I'd like to take this opportunity to say congratulations to all those who have made such positive efforts to kick the habit - very well done," BBC quoted her, as saying.
"This shows that the investments that we are making in helping smokers to quit are having a positive impact," she added.