What drug has the same effect as codeine?

Yes, but:

1) Amount of codeine in syrups is usually a lot lower then in pills.

2) When using a syrup, you're looking at a 99% chance of projectile barfing.

Besides, you can't perform CWE on syrups, which makes them pretty much useless for the purpose of getting high, if you're planning on staying alive (Acetaminophen)