Cocaine is far more water soluble than baking soda. Extremely, extremely water soluble -- about 2 grams of cocaine can dissolve in 1 ml of water (compare to baking soda: About .1 grams per ml of water)
But you also have to get rid of the packaging. I was imagining dumping a package of cocaine, but that's stupid: at least opening the packaging would help with the clogging by letting the cocaine dissolve. Not sure what the packaging would do with the pipes and whether this only packaging holds up as evidence.
You can't clog a toilet by flushing cocaine.