Hello,
Welcome to PC. I am sorry your brother and you and your family are going through this challenge. If your brother is not in therapy it would be beneficial for him and your parents to get therapy. It will help teach your brother how to deal with the ADHD and teach your parents how to help him manage his behavior and set appropriate limits and deal with his explosions. There are multiple types of medication for ADHD and some people will respond to some while some will respond to others. If you would not feel comfortable recommending therapy for your brother to your parents, maybe recommend that they talk to the school social worker or counselor about ways they can get him help, which will hopefully lead to a recommendation from them for him to get therapy if he is not already. With an ADHD diagnosis he may qualify for special education supports at school if he needs them. Having a sibling with behavioral and mental health issues (really any issues) can be very challenging. It sounds like you are a very caring older sibling and he is lucky to have you.