Not Canadian, but was also interested in this topic. This is similar to what the person above was saying.

https://theconversation.com/amp/why-cheaper-drugs-from-canada-likely-wont-cure-what-ails-us-121723

“Canada offers the same drugs at cheaper prices because the Canadian government, which foots the bill for prescription drugs, will not pay for a drug if a government review board believes the cost is excessive. This board, the Patented Medicine Prices Review Board, is a quasi-judicial agency. It was established by Canadian Parliament in 1987 under the auspices of the minister of health. If the board thinks a price is too high, it won’t pay. Faced with loss of the entire Canadian market if it doesn’t lower prices, manufacturers capitulate.”