In April, Claudine Michelle Herewini, was charged with manslaughter of a 9-year-old by administering methadone. Herewini, of Raetihi, will reappear in court next month.
Two weeks earlier, Wanganui man Matthew Shane Johns, 36, whose girlfriend died after he helped her shoot up methadone, was sentenced to two years and seven months' jail for manslaughter. Both Johns and girlfriend Sanchia Wilson were long-time methadone users.
Clive Kenneth Beach, 58, a registered methadone user, was also sentenced to 10 months' home detention in relation to Sanchia Wilson's death after admitting three counts of supplying the drug.
Dr O'Connor said methadone treatment was carefully monitored.
"When starting on methadone there is close supervision of the medication, most of which is taken under observation at the pharmacy.
"Once the person reaches a dosage level which takes away the desire to seek other drugs and, as their lifestyle becomes more stable, the person takes more of the medication at home."
Suboxone, which could be prescribed as an alternative to methadone, had become available in the past year, he said.
The Health Ministry warns that ceasing use of opioid drugs is not the general goal of the treatment.
"For some clients, it will be appropriate to attempt a supervised reduction and withdrawal of opioid drugs," Director of Mental Health chief adviser Dr John Crawshaw said.
"Other clients may receive OST for the rest of their lives, with medical supervision and advice ... at a level which allows them to function normally."
A Christchurch study estimated nearly $131,000 was saved each year in "societal costs" when an opioid addict was treated through a methadone programme.
Making OST more accessible and stabilising addicts earlier led to substantial reductions in expenditure on drugs, crime and imprisonment.
In New Zealand, the most common opioids were legitimately prescribed, usually for pain or addiction treatment, Dr Crawshaw said. These included methadone, morphine and oyxcodone. APNZ