Dunno if it's already been said - got a bit frightened by some of the earlier answers and wanted to get in quick.
Whether you do this as a transfer of funds or withdraw cash to pay it, it WILL count as a cash transaction, and a cash transaction on a credit card - especially a big amount - is a very very very bad idea. You will be paying interest from day one, on a daily basis, possibly at a higher rate than for purchases, until the amount and any accrued interest is cleared. It will take forever.
Best bet if you really need to to something is see if you can get another loan at a lower rate than you are currently paying or as I think said, overpay if you can.