A tearful Premier Jacinta Allan has revealed her husband, Yorick Piper, was stripped of his driver’s licence for drink-driving during a morning trip to the supermarket moments after a minor collision.

Allan said she was deeply embarrassed that her husband had recorded a blood alcohol reading of 0.05 when he was intercepted in Bendigo shortly before 9am on Thursday.

“My husband, Yorick, was driving to the supermarket in Bendigo to pick up some groceries when he was pulled over for a random breath test,” Allan said.

“As a result of this test, he blew 0.05. He has, as a result, received an on-the-spot fine and lost his licence for three months.”

Allan said her husband currently takes medication, and experts say some drugs can lengthen the time alcohol spends in the body.

When asked if her husband suspected he might be over the limit, she replied that he was “incredibly shocked” as he had been going about his routine household duties, unaware he was over the legal alcohol limit.

“We’re shocked, deeply embarrassed as well,” she said.

“Physically, he’s OK … But yes, we’re embarrassed and shocked and most truly sorry for what has occurred here because drink-driving and road trauma are incredibly, incredibly serious.”

Allan said she and her family were celebrating her son’s birthday at their local pub on Wednesday evening and headed home about 8pm.

“My husband is also currently taking medication for a health issue, and as a result of the medication mixing with the alcohol from the night before, he simply shouldn’t have been driving the following morning,” she said.

Allan said there was no excuse. “He understands that. I understand that, and for this, we are both truly sorry.”

Piper was involved in a bingle shortly before his random breath test, having “bumped into” the car in front of him when it came to a stop at an intersection about 8.45am on Thursday.

“Both he and the other driver were not injured, and given it was a minor collision, they – both drivers – shared details, shared information, exchanged details after stopping, and both continued on their way,” the premier said.

Piper, a board member of the Fisheries Research and Development Corporation, continued on to the supermarket and was then stopped by police for the random breath test just before 9am.

‘Physically, he’s OK as a result of yesterday. But yes, we’re embarrassed and shocked and most truly sorry for what has occurred here.’

Premier Jacinta Allan

Police said in a statement that Piper, 56, was stopped in Mitchell Street, Bendigo as part of a statewide road policing operation.

“The driver received a penalty notice carrying a $611 fine and his licence was cancelled for three months,” police said.

“He made his own arrangements to leave his vehicle and left the site on foot. There have been no reports to Victoria Police in relation to a collision just prior to the preliminary breath test.”

Allan said her family would cover the cost of repairs to the other car, which has a minor dent, and that they had made a $1000 donation to road safety charity Amber Community.

Piper’s licence suspension will come into effect from January 16.

Under new laws introduced by Allan’s government last year, Piper will also face a mandatory three-year period where he must have a blood alcohol content of zero while driving.

“I hope this can be a powerful lesson,” Allan said. “If there’s a lesson to be learned here, the lesson is don’t get behind the wheel. At this time of year when there’s a lot of activities, a lot of festive cheer going on, please do not get behind the wheel.”

Amber Community, which provides free counselling to those affected by road trauma, confirmed the premier had made a donation.

“Road trauma can happen in an instant. This festive season, we encourage everyone to plan ahead, make safe choices, and never underestimate the impact of alcohol, fatigue, distraction or medication on driving,” the charity said in a statement to The Age.

Nial Wheate, a professor of pharmaceutical chemistry at Macquarie University, said some medication affected the metabolism of alcohol.

He said enzymes in the liver that break down alcohol also break down medicine but can’t work on everything at once, leaving alcohol in the body for longer.

This also means people can be legally impaired at lower levels of drinking.

“Let’s say for a person, it takes them three beers to get over the blood alcohol limit. If you’re taking a medication, it could mean that you could be over the limit with only two or one beer,” Wheate said.

Wheate said antibiotics were one category of drug that affected the liver, and blood pressure medication such as antihypertensives were shown to make alcohol stay in the body for longer and increase blood-alcohol readings.

He said anyone taking medication should talk to their pharmacist for clear advice and, if their drug affects alcohol metabolism, they should either not drink or ask someone else to drive.

“I wouldn’t support advice saying wait longer or anything like that because people are terrible judges,” Wheate said.

“One person might have very clear signs of being intoxicated and have their blood alcohol limit below 0.05 and other people might have very little effects if they’re seasoned drinkers, and they can have a blood alcohol limit well above that.

“You cannot judge blood alcohol concentration either by yourself or even have other people looking at you and knowing it.”

Dr Erin Lalor, chief executive of the Alcohol and Drug Foundation, said mixing alcohol and other drugs could also have a toxic effect, increase side effects and make some medications less effective.

She said multiple factors could influence blood-alcohol readings, including weight, body composition, food consumption, age, sex and other health conditions.

Opposition Leader Jess Wilson said drink-driving was unacceptable and serious.

“But I’m not going to comment on the premier’s family. It’s not who I am to comment on someone else’s family, and she’s addressed those issues this morning,” Wilson said.

Get alerts on breaking news as it happens. Sign up for our Breaking News Alert.