How does the pharmaceutical companies of US and canada keep the cost of drugs down. Why don't Canadians market drugs to consumers?

How does the pharmaceutical companies of US and canada keep the cost of drugs down.  Why don't Canadians market drugs to consumers?  What are the major differences in pharmaceutical sales in the US vs. Canada?  How do these differences keep costs down? it should explain that the cost of parmaceutical in US than compare to canada.

It should be a 8-9 pages docment in APA format with references and no plagiarism. Please no copy paste.