If you are un happy with the doctor and feel your friend is suicidal , get in touch with the practice and ask for help , also you could contact the local mental health team who are on call 24 hours, they can asses them and they can make things happen . especially if they are saying they will self harm
failing that call an ambulance and hospitalize them that way , perhaps he has a history ?? that only the doctor knows about ?? hope this helps .... better to get help than not to and regret not actioning your thoughts .......