unfortunately it's very difficult to successfully OD on medications bother over the counter and prescriptions. all meds are designed to be as safe as possible for humans, so it generally takes an extremely high dose for anything to work, and even then it isn't guaranteed that you would die. I'm not well versed on which medications are most likely to work but just be careful on what you decide to go with, because it could leave you with organ damage or other permanent health issues.