Drug-driving detections have more than doubled compared with last year.
New garda statistics also show that despite a huge reduction in the volume of traffic during the Covid-19 lockdowns, the death rate on the country's roads has increased.
The figures were released as An Garda Síochána launched its Christmas and New Year road safety appeal and urged drivers not to drive after taking alcohol or drugs, lower their speed and be mindful of cyclists and pedestrians.
Assistant Garda Commissioner Paula Hilman, of the National Roads Policing and Community Engagement Bureau, said 136 people have died on Irish roads this year.
"That is eight more than last year in a time when traffic volumes were actually down as much as 70pc during lockdown restrictions," she said.
"Last weekend alone there were 85 alcohol detections and 26 drug detections on our roads.
"Even with reduced traffic volumes, there were 2,573 people found driving under the influence of drugs this year compared to the same period last year. That's an increase of 113pc.
In the same period, detections for drink-driving fell 24pc from 7,675 to 5,849.
Ms Hilman also said a new pattern has emerged where detections for drink or drug-driving are more evenly spread across the week rather than in a spike at the weekend.
It was unclear if Covid-19 was responsible for this shift in patterns of public behaviour.
Ms Hilman said speeding offences are up by 26pc this year to 151,000 cases so far.
Road Safety Authority chair Liz O'Donnell said increases in drug-driving and speeding have had a direct effect on road deaths.
She said the increase in detections of people driving while under the influence of drugs was of particular concern, and while there had been a drop in drink-driving detections, gardaí are "playing catch-up" with those driving after taking drugs.
"Passenger deaths are also up, and the non-wearing of seatbelts may be contributing to this," she said.
Ms O'Donnell said the latest figures show that where toxicology tests were carried out on road death victims, more than one-third had alcohol in their bodies, nearly 10pc had taken cocaine and more than 7pc had taken cannabis.
"The pubs may be closed because of Covid, but people are still getting alcohol and still getting into cars," Ms O'Donnell said.
"If you are drinking at home you have to be careful of the measures you pour. We pour twice the normal level at home without realising."
Hildegarde Naughton, the Minister of State for Inter- national and Road Transport and Logistics, urged tired drivers travelling long distances to stop for a caffeinated drink and take a 15-minute sleep before resuming their journey.
"Share the driving if possible, but don't try to fight off sleep behind the wheel," she said.
An Garda Síochána's Christmas and New Year safety campaign will run until January 5, and there will be high-visibility checkpoints and mandatory roadside intoxicant testing.
Professor Denis Cusack of the Medical Bureau of Road Safety said extra roadside testing units have been issued to gardaí to help in the detection of drink and drug use among drivers.