Your friends are gambling with their lives. Herion is a killer I know first hand my son died taking this evil drug. Herion gets a hold on your soul and doesn't want to let go untill they want to beat it and it is not a over night thing. The one important thing is your friend has to want kick it no words from you will change things. He has to make up his mind to stop. So tell him when he is ready you will support him don't put yourself through all the heart acke when the drug is the most important things in his life.
I will pray for you and your friend
Maggiemac