Yes there is an interaction with Welbutrin (also known as Bupropion and Zyban). It is processed by the P450 cytochrome, mind you its not a big interaction apparently. I myself used on PI's. Just be very carefull if he boosts it. If you get good relief from the 75 then stick to that, you should feel the benefit of antidepressant therapy within 3 to 4 weeks. So I would give it at least 4 weeks on the 75. If you have to go on the 150 be carefull, as of about two years ago we had at least 11 deaths attributed to Welbutrin in Canada alone. There are a lot of antideppressants on the market and Welbutrin would not be my first choice because of the interaction with HIV meds. I don't know if there are interactions with Ambien but there is one with Viread, it lowers Reyataz levels, but by boosting it with Norvir takes care of that problem.
José Sousa