Gerry Angus said he knew his son Glen (38), who was an intravenous drug user and a member of the methadone programme, and died in November 2007, "would not live to be an old man".
After the publication of the coroner's report, Mr Angus contacted the Otago Daily Times earlier this month to express his concerns about drugs and the people who sell them.
"I personally would like to see all class A drug dealers hung, drawn and quartered," he said.
He was concerned about the large supply of prescription drugs entering the black market.
It created a "lolly jar" for drug users.
Under the Medicines Act (1981), prescriptions can be written for up to three months, and dispensed monthly.
Mr Angus would like to see prescriptions written for one month in an effort to cut the supply of drugs entering the black market.
Older people selling prescribed drugs, and people feeding their children sugary treats before taking them to "soft-touch" doctors in order to obtain Ritalin, for the treatment of attention deficit hyperactivity disorder, were some anecdotal reports he had heard about the misuse of prescriptions.
A New Zealand Police spokesman declined to comment, referring all comments to the Ministry of Health.
A ministry spokeswoman said the ministry monitored the misuse of prescription and controlled drugs, including morphine, methadone and methylphenidate.
In October 2003, Pharmac, the drug-buying agency, changed the rules for dispensing medicines by allowing doctors to prescribe a 90-day supply of certain medicines to be dispensed at once, rather than over three visits to a pharmacist.
Certain medicines, such as some antidepressants, were usually dispensed monthly with two repeats, because of the risk of overdose, the spokeswoman said.
Pharmacy Guild of New Zealand chief executive Annabel Young said when dealing with "human behaviour", no system was foolproof.
"No situation is perfect when you are dealing with addicts. They are well known as being incredibly cunning," she said.
Mr Angus said he would like to see mandatory sentences imposed for drug dealers.
Minister of Justice Simon Power said Parliament had "indicated the seriousness of class A drug offending by setting life imprisonment, New Zealand's most severe sentence, as the maximum penalty for offences such as importing/exporting, manufacture, and supply".
