Sorry to rain on your parade but if your name isn't on the prescription, and you can't demonstrate that it is a reasonable amount of the drug for your own medication during your visit, save your money and leave the drugs at home.
Same goes with freight. It's a controlled substance or it wouldn't be perscription. You have to have a license to ship those and the recipient has to have one as well as I understand it.
Either act could land you in jail as like it or not, you are technically smuggling drugs.
US Customs
http://www.cbp.gov/xp/cgov/travel/cl...tion_drugs.xml
HM Revenue and Customs
http://customs.hmrc.gov.uk/channelsP...yType=document
Most if not all countries have such rules. Some with rather drastic penalties.