There's nothing in the cut thats makes you paranoid, its the coke itself. Its called cocaine physchosis. Comes after several years of doing it. Most people get it and once youve got it it doesnt go away. The only way of making it partially disappear is by taking diazepam, or alcohol, and not doing too much of the stuff.
I used to get terrible paranoia, usually end up locking myself in the bathroom for hours on end.
What stopped the paranoia was stopping mixing alcohol with gear and only obtaining gear with no cuts and clean, very clean i mean. The difference is remarkable. Tiny bumps every few hours, relaxing and tingly buzz and no paranoia and no urge to redose. I tried the clean stuff with alcohol and the paranoia returned. Now i dont crave either and it's an occasional and enjoyable thing for me, just like it was in the beginning. Basically cut gear is a big factor and alcohol plays it's part too.