Wayne Marshall had been trying for years to give up smoking and became the first patient at his GP practice in Doncaster to be prescribed newly-licensed drug Champix.

But the 36-year-old welder hanged himself in November shortly after completing a 13-week course of the medication.

His suicide is the second in the UK to be linked to the drug after the death of a 39-year-old man from Lancashire in October.

European regulators last month ordered improved warnings to patients over the twice-daily prescription medicine amid reports it could lead to depression.

Latest figures from the Medicines and Healthcare products Regulatory Agency (MHRA) show one patient has taken his life while on the drug, two others have attempted suicide and there have been 60 other suicidal-type suspected adverse reactions reported.

Last night Mr Marshall's wife Emma, 28, said he was prescribed the drug in August but quickly went downhill, cutting himself off from his family and friends. He was signed off work a week before he died, but had given no signs he was contemplating ending his life.

She had moved out of the couple's home in Rossington a month earlier and he had once before attempted suicide as a teenager. Last month an inquest verdict recorded that he had killed himself.

But Mrs Marshall had since discovered Champix has been linked to depression and was concerned the drug had played a part in causing his illness.

Now she has reported his case to the MHRA under its early-warning yellow card scheme.

"I don't want anybody to have to go through what myself, his children and his family and friends are facing. It's horrendous," she said.

"I think people need to think about going on this drug, particularly if they have a history of depression."

Mrs Marshall, a distribution co-ordinator at a car firm, said her husband had tried everything to quit his 20-a-day habit including patches, inhalers and a course of another drug but nothing had worked.

He had not smoked while on Champix but became quiet and withdrawn and one day she found him sobbing uncontrollably.

"I don't understand how he went downhill so quickly. He stopped going out – there were all sorts of things he stopped doing," she said.

"He loved socialising, going out with the lads, watching Doncaster Rovers and he had a big circle of friends. He was not the type of person who needed picking up but his whole personality changed. He closed himself off completely from everybody.

"He had been trying to give up for a long while. These tablets did seem to be working – it was just his moods."

Her husband, who had two children from his first marriage, had previously worked as a prison officer and received two commendations for saving the lives of inmates who had attempted suicide.

She had been the last to see him alive. He had finished the drug course a week earlier but had immediately taken up smoking again.

"He was more positive than when I saw him previously. We were talking about Christmas and he seemed better than he had been," she said.

"Never ever could I have dreamt he would have done something like that. It never crossed anybody's mind."

A MHRA spokesman said Champix was being carefully monitored.

Latest figures this week show it had been sent more than 1,600 reports of suspected adverse reactions relating to the drug which has been taken by 200,000 people in the UK. There had been 63 cases of suicidal-type reactions including one suicide.

He added: "Giving up smoking can be very stressful. The side effects are suspected. It doesn't necessarily mean the drugs caused the reaction."

The European Medicines Agency (EMEA) decided last month to update warnings following reports of suicidal thoughts and suicide attempts in patients using Champix which first emerged in July.

It said doctors were already aware of the risks of prescribing the drug to patients with an underlying mental illness and needed to be aware of the possibility patients giving up smoking could become depressed.

It advised patients taking the drug who experienced suicidal thoughts to stop their treatment and contact their doctor immediately.

In a statement, it said: "It is very difficult to know if this is due to Champix, as the act of stopping smoking itself can make people depressed, especially if they already have a mental health problem."

Drug giant Pfizer, which makes Champix, also known as varenicline, said it was working with the EMEA to review reports of depression and suicidal thoughts.