The drug is marketed as a component of at least two supplements sold in New Zealand - Pro Supps Mr Hyde and Platinum Labs Amino Grow.
A police statement said the Ministry of Health, national drug intelligence bureau (NDIB), police and customs monitored the prevalence of illegal substances and undertook controlled purchase operations to ensure the law was being complied with, but it was unclear what action would be taken over the sale of the supplements.
"Wherever police have evidence of criminal drug offending, we will investigate and take action as appropriate," NDIB co-ordinator John O'Keefe said.
The Herald discovered at least six supplements retailers selling Pro Supps Mr Hyde and Platinum Labs Amino Grow for around $60 for a 30-serve tub.
Marketing material on the website of Punch Supplements describes Pro Supps Mr Hyde as one of the "most potent, high stimulant, energy-based pre-workouts legally available in New Zealand" - a product that "wires your mind and thumps your heart" suitable for "stimulant junkies".
The person who answered the phone at Punch Supplements' Auckland warehouse referred the Herald to the company's Australia parent MrSupplement.co.au, which did not respond to messages.
In February, the Herald revealed New Zealand retailers were selling a product called Frenzy, which contained a banned stimulant (DMBA).
DMBA is chemical cousin of DMAA - a stimulant linked to multiple deaths following its use as an exercise supplement.
Manufactured by American company Driven Sports, Frenzy was marketed as the replacement for Craze, a Driven Sports supplement found to contain an analogue of methamphetamine. An advertisement for Pro Supps Mr Hyde compares it to Craze.
The presence of picamilon in supplements was concerning as its effects were "entirely unpredictable", said Harvard scientist Pieter Cohen.
"Why this drug would be used in a pre-workout supplement is hard to fathom, unless it's to give a pleasing sensation to the consumer that leads them to purchase more," said Dr Cohen, one of an international group of scientists that produced a research paper on picamilon published in the journal Drug Testing and Analysis.
Dr Cohen's research found doses of the drug in US products often deviated from what was stated.
"We learned that dosages of picamilon were often much higher than even the highest prescription doses, and ... the customer would have absolutely no idea how much picamilon they were consuming by reading the label. This is a scary thought even for a consumer who didn't mind experimenting with unapproved drugs."
Health products?
Sports supplements continue to be formulated using substances illegal or unapproved in New Zealand, including:
• Methamphetamine analogues: Discovered in the popular supplement Craze.
• DMAA: Widely used in pre-work supplements, now banned following links to the deaths of multiple users.
• DMBA - chemical cousin of DMAA: Banned in NZ under Psychoactive Substances legislation but found by the Herald in February to be on sale as an ingredient in the supplement Frenzy.
• Picamilon: Class B substance used in the manufacture of date rape drug GHB. On sale in NZ as ingredient in Pro Supps Mr Hyde and Platinum Labs Amino Grow.