Glenn Hay yesterday publicised his findings into the suicide death of a Hobart man in November, 2009 - seven weeks after he started taking Varenicline tartrate medication Champix in an effort to quit smoking.

The coroner found sufficient evidence of a connection between the man's sudden death and the drug to alert the community to its risks.

He emphasised the importance of patients disclosing any relevant medical history to doctors.

"It is also important for patients to stop taking Champix and contact their healthcare professional immediately if changes in behaviour or thinking, agitation or depressed mood that are not typical for the patient are observed, or if the patient develops suicidal ideation or suicidal behaviour," Mr Hay found.

The victim - who is not identified - had a successful painting and decorating business with his brother, was married, and had three children and a stepson.

But after being prescribed the drug, the man's wife reported that he became "more irritable, aggressive, and difficult to get along with".

He had told his mother the drugs made him feel "queer" and had asked his sister to look up the side effects on the computer four days before his death.

But he refused to stop taking the medication.

On the night of November 6, 2009, he fought with his wife and she decided to take their children and stay at her mother's house.

She returned the next morning and saw the open gun safe and her husband's legs prone on the floor.

Another family member arrived shortly before emergency services and they discovered him dead with shotgun- inflicted wounds.

Toxicology analysis revealed he had a blood alcohol level of .204.

The anti-smoking drug, however, is not targeted in drug screening, with Mr Hay finding that no laboratory in Australia tests for it.

But Mr Hay also found an "enigmatic and somewhat puzzling factor" in the circumstances of the man's death.

Investigating police found the shotgun's safety catch on - which would not occur automatically after firing.

The victim could not have done it himself - and further investigations failed to explain the anomaly.

But both police and the coroner ruled out foul play, with possible explanations including a family member or emergency services personnel member securing the gun automatically upon arrival without remembering they had done so.

•Mental health- related support and advice can be accessed via Lifeline on 131114, MensLine Australia on 1300789978, or beyondblue on 1300224636.