Think about it this way.
Legal matters aside, if the United States imports or reimports pharmaceuticals from Canada, eventually, Canada will run out of supply and the price will go up for Canadians and finally reach equilibrium with the United States. Canadians won't get the drugs they need and eventually most won't be able to afford the price increase. In the long run, we don't benefit and the Canadians lose.
If drug manufacturers priced drugs equally all over the world, most countries (for example, many countries in Africa), would not have access to new and life saving drugs. From my understanding, drug companies base price on some kind of system-like the GNP for setting price. If we continue to import from outside countries, eventually, price will come to an equilibrium. The United States would benefit from cheaper drugs but at the same time take drugs away from other countries.
The United States is a rich nation and if we want to continue to have access to the latest drugs, our scientists have to do the research and development. Only 5% of drugs make it to the market-and even then, it's a risky business (take Vioxx for example). If we want to continue to be leaders in pharmaceutical development, we've got to pay the costs to encourage R&D.
At the same time, I know it sounds like I'm saying that we should just bear the burden for the world but that's not my meaning. I think that in order to solve the high cost of prescription medication and health care for that matter, we need to come up with an internal solution.
Why not have the government buy out patents so generics can be available sooner? (The money the govt can save on generics can be used to pay for patents)
Have you noticed the increase in drug ads? Many manufacturers spend as much money on ads and marketing as R&D (all those free pens and stickies you get in the pharmacy aren't "free").
The point is, there are a lot of contributing factors. The solution isn't simple. You can't just expect that importing will solve the problem. It's just a temporary solution.