Be Careful
Phenobarbital would probably help keep you 'chill' while doing your coke, but remember phenobarbital is pretty weak compared to other barbiturates and it may be better for using while coming down off coke. PLus maybe next time don't do as much coke, if your getting paranoid and fast heart rate that bothers you then you may be just taking too much.. If you have any xanax or valium or another benzo that would be your best bet for taking the 'edge' off while doing your coke... But if you wind up going with Xanax make sure you don't over-do it and become a babbling blacked-out coked out retard and doing something you regret.. If you can get Valium, Ativan, or k-pins that would be a better bet as you would be less likely to black out and Klonopin ,in particular, would be good cuz you could just take 1 or 2mgs and it would last all night while your doing ur coke and keep you a lil more chill... Just remember to be safe, and using benzos with coke can actually be safe as I am pretty sure they give you a benzo in the hospital if you end up ODing on coke, but i am not 100% sure..Just be careful bro.