The best way to approach your friend in this situation is to be compassionate, non-confrontational, and supportive. Approach them in a private setting, away from the crowd, and calmly express your concern for their safety. You can say something like, "I noticed you've had a lot to drink, and I'm worried about you. Let's get you home safely, okay?" Offer to call a taxi, rideshare service, or drive them home yourself if you are sober.
An approach that would likely not work is confronting them publicly, being aggressive, or trying to shame them for their behavior. This could make your friend defensive and less likely to accept your help.
If the situation were reversed, you would likely want a friend to approach you with the same level of care and understanding. You'd appreciate it if they didn't judge you or make you feel embarrassed, but rather, focused on ensuring your well-being and getting you home safely.