Some of the concerns here are justified. Mexico's pharmaceutical industry is badly in need of better regulation and enforcement. First off, given the amount of senior citizens coming to border towns from the US, the pharmacies in the border towns would be more likely to try to rip-off foreigners.

Also, many of the no-name generics made in countries like Mexico could be of suspect quality. The patent protection given to new drugs aren't in place there in a lot of cases, so you'll find generics for Norvasc and Lipitor even though the patent protection in the US is still there.

The best advice would be to spend a little extra on brand-name products in Mexico if they sell them. They usually come in the same name as the US versions but not always, but the manufacturers should be the same: Pfizer, J&J, Wyeth, GlaxoSmithKline, AstraZeneca, Bristol Myers-Squibb and so on. Many of these large pharmaceutical companies have factories in Mexico and Europe making high-quality versions of the drugs that they have patented. And those will be cheaper in Mexico than in the US.