Nurofen Plus - I used this for two reasons. The first, it has the highest concentration of codeine per pill than any other OTC codeine product on the New Zealand market. Secondly, ibuprofen is - I believe, please correct me if I'm wrong, but that's what I've read up on this - considerably less toxic than APAP.
That means that, yes, although ibuprofen can't be completely filtered out, so you'll never had a clear solution like you should always aim for with APAP, it's not too serious a deal. Just get it as clear as you can.
I would filter first through a clean while cotton tshirt, then through three coffee filters layered together. I assure you, this works just fine. However, I also left the dissolved solution in the fridge for at /least/ two hours, but sometimes as long as overnight. This lets all the gunk settle to the bottom and separates everything else into a clear fluid floating on top, and probably makes a difference.
I'd always smoke a bowl with it as well, helped bring it on. I moved on to bigger things, so I don't use anymore, though it's also worth noting that my most horrific constipation episode (two hours - I checked the clock - in the bathroom in bite-down-on-my-sleeve agony most of the time, honestly thinking at a few points I really might rupture something or have a heart attack and die, and being left with a bleeding ass) was due to codeine. If you're going to use it regularly - and I was really only doing it most weekends - make sure that you're taking fibre supplements with it and have laxatives on hand for when you notice you haven't been in a little while... I've had an episode nearly as bad on smack, but nothing has ever beaten that that.