Firstly I can't tell if you're a troll or not.
If you're serious then no you can't get your brother struck off. In the long run it would be your word against his, do you have any proof he gave you drugs? It would be an incredibly difficult thing to prove.
And the fact you've had mental health issues would unfortunately make it even more difficult.
I hate to say it but it sounds as though you have a bit of a chip on your shoulder where your brother is concerned. Whether he graduated 'low' or not, he became a dentist, that's quite an achievement.
If he's such an awful guy just cut him out of your life and move on - don't visit internet forums asking whether you can 'ruin your brother's life' that's just unhealthy and a bit sick to be honest.
Which unis have sent theirs?