I think that unless you're privy to all the information that the admissions staff are using to judge acceptance, including the quality of the competition and a myriad of other factors that you or I may not have considered, it's a bit of a stretch to assume your friends were racially discriminated against. I don't know how many people you're talking about, but assuming it's a relatively small number, the rejection of most/all of your Asian friends to study medicine could just be down to chance.