This two paragraph exert doesn’t make sense.
Why would a U.S. law affect pseudephedrine availability in Mexico?
Is the article suggesting parents are buying Adderall on the black market or from otherwise unlicensed distributors?
I don’t think that is what he meant. He meant that the misguided government effort to ban pseudoephedrine here only led to drug dealers and users finding alternatives in China and Mexico. Every time the government tries to fix something it leads to unintended consequences.