A one-month-old baby, who was accidentally given methadone, remains in a stable condition at Hawke's Bay Hospital.
The infant was admitted to the intensive care unit (ICU) last Tuesday, after reportedly being given methadone by mistake at a Hawke's Bay community pharmacy.
National Poisons Centre director Doctor Adam Pomerleau said methadone poisonings were extremely rare in New Zealand.
"We get around 25,000 calls per year about poisonings, but when it comes to methadone, I wouldn't expect the number to be zero, but it might not be much more than that.
"Methadone is a opioid medication and like all other opioid medications, they all produce very similar effects on the body.