The 'Simple Life' star has been sentenced to four days in prison after she pleaded guilty of the charges. In an interview to ABC's Diane Sawyer, Richie opened up about her DUI arrest.
"I had smoked marijuana that night, just marijuana. I had Vicodin in my system from that day, which I take for pain," Us Magazine quoted her, as saying.
Richie added that she did something wrong, and that she wants to apologise to everyone who has lost their loved one from drunk-driving.
"I have a responsibility and it's something that I did wrong, and if I could personally apologize to every single person that has lost a loved one from drunk driving I would. And unfortunately I can't, but this is my way of paying my dues and taking responsibility and being an adult," she added.
On the show, she also revealed that she is expecting her first child with beau Joel Madden.