One of the two in the oncoming vehicle had a broken leg, a broken nose and a serious lip laceration, and the second had soft-tissue chest injuries.
The summary said a sample of blood from Hudson revealed use of meth, morphine, cannabis and ketamine.
The crash happened when the northbound vehicle he was driving veered across the centre-line on the Mountain Rd section of State Highway 3 between Stratford and Inglewood and collided with an oncoming vehicle, just outside the township of Cardiff.
Conditions were said by police to have been "dry and well-lit by sunshine".
Reports at the time said four ambulances and a rescue helicopter were used to take the injured to hospital
In court Hudson pleaded guilty to five charges of drugged driving causing injury, which carry a maximum term of five years' jail. Also admitting other charges, including failing to answer District Court bail, he was remanded in custody for sentencing in the Napier court on December 3.