Prevent a Customer from ordering a specific product

Currently, we ship selected items to Canada but there has been a recent change with Canada FDA that we are now not allowed to ship selected products. Is there a way in Customer Maintenance module to not allow the selected items to be entered in the Sales Order module for this particular customer only?

If not, what are some other options other use to make it known that the selected item cannot be shipped? We already use the memo notes which would not be useful for this situation.