This law is misguided.
If drug manufacturers are losing money due to re-importation, they can raise their prices abroad or lower them here. If price controls in other countries prevent higher prices, the manufacturers can refuse to sell there.
U.S. patent laws protect U.S. manufacturers from infringement of their patents. And U.S. laws against fraud protect manufacturers and consumers from fake medicines. The ban on re-importation, however, applies even to drugs that are legally sold abroad, and even when U.S. customers have valid prescriptions.
The justification for banning re-importation is therefore weak. The law is difficult to enforce, so evasion is successful much of the time. The people who suffer most are low-income U.S. citizens who obey the law.