OTC, probably not, the way they generally work is by putting an excess amount of "salt" in your large intestine which causes yor body to pump in water to wash it away, but it takes a lot of rinses to get rid of it.
As to the why not antibacterial soap question, your gut is home to loads of bacteria that function to digest food and create nutrients you cant (vit. d for example), so killing them is bad. They also kill off most harmful bacteria, so the wholesale slaughter of the native flora and fauna is not advised, especially since you dont know who will move in after them.
As for enemas, a lot of people will do coffee as an enema, honeslty i dont know why, they just do. Here's a safe bet, if you wouldnt swallow it, dont stick it up your bum (I know a lot of the other things we've said you wouldn't swallow, but im talking about things around the house you were considering), and if it burns going down when swallowed, its probably going to burn in your bum, so dont do it.