Is it ever established how recently the u4ia drug was developed? If it is relatively recent, it could have been an antidote to the poison that MC had ingested and his father funded the R&D, only for it to have additional effects.
A year in hospital being pumped full of experimental drugs, only for Jack to break him out and have MC being driven to get as far away as possible, only to end up back at the door of the woman who poisoned him.