I have not used the search engine to check, but since I'm prescribed the pills and the suppositories I'm thinking it might not work well. But even swallowing them makes them work pretty fast.
I personally don't feel like my suppositories work a lot faster, but I take them during migraines when I can't keep any medicine down. I let a klonopin dissolve under my tongue and use a suppository and I usually throw up 4 or 5 times before it starts to work.
There have been many comments about promethazine so I'd check the search engine or WebMD.