OTC meds, http://www.coldwaterworld.com will probably be the best for that- has a ton of OTC meds listed and how/why they work.
As far as Klonopin, that's only going to make the sedation stronger, but not by that much if you take your usual prescribed dosage. Me personally, Valium is the post benzo potentiator because it has muscle relaxant qualities, kicks in quickly, and the sedation lasts.
Look into tagament and the various OTC antihistamines, keep an eye out for those when you check out coldwaterworld (which doesn't have extraction info on it anymore, btw, for anyone concerned about that- now it only has info on potentiators.