I don’t know about Canada, but it’s very hard to get in the US right now, though it can be ordered from the manufacturer. I called a bunch of pharmacies, covering all three major wholesalers, and came up dry. I finally may have found it at Sam’s Club - I’ll see tomorrow if the order comes in.
The web site has a small-print message saying it’s intended for U.S. residents only. What message do you get suggesting that it’s shut down to Canadians?