It all depends on the amount of alcohol ingested.
If your friend has been drunk, you will need to take all the necessary steps to get him safely home.
You can call a taxi, which is very convenient as it only involves you and your friend. You'll quickly get home and you'll help him in what he needs to improve.
Another alternative is to ask for help from someone you know at the party, someone who has not had a drink. Maybe that person can provide the help you need. However, it is important that this person is trusted and has not drunk.
Lastly, a third alternative is to call your parents or your friend's parents. So some of them will get you.
