Not only could your shipment be confiscated,
you could face criminal charges for the illegal distribution of controlled drugs across international borders. These are dangerous substances, and their use for athletic performance-enhancement is banned in all of organized sports at all levels in the U.S. The medically-sanctioned uses for them are rather limited and if this was the case then you could get them in the U.S. by prescription from a licensed physician. My recommendation: don't do it unless you really wish to put yourself and others at unnecessary legal and medical risk.
- Tordok