It's explicitly stated to have ultra-regenerative effects; pretty sure it is indeed meant to magically heal him, basically because it's obvious Oda simply created an ad hoc tool so he could follow both the rooftop and the King-Queen vs. Zoro-Sanji routes.
What was stated was that the drug will allow Zoro to move again but the side effects would double the pain, with Zoro saying he needs to fight and decided to take the drug, the drug is not a senzu, there drug just made Zoro’s body ignore its damaged state but the damage is still there and when the effects run out Zoro will feel all that pain all at once.
Again the drug did not heal Zoro, it’s just making his body forget the pain for a period of time but the effects will eventually run out.