Coke would effect creatine big time if they were taken together.
Creatine is a buffer, that is it will somewhat neutralize acids or bases wherever it is.
It works for us by neutralizing lactic acid in the muscles.
But if you take it with coke, a strong acid, or any soda.... it will start to neutralize that acid in your stomach, and lose its efficacy.
This is actually why creatine is needed in such large doses, so much is destroyed by stomach acid alone. Coke or Pepsi would only add to this.
Hope this helps. I know its nasty but washing it down with water is best.
But then again, I dont even think that shit works