The seizure of up to $60,000 of pentedrone from southern addresses was only the second case in 18 months in which the illegal drug, often referred to as ''bath salts'', had been detected being brought into the country.
On Thursday, police charged a Dunedin man and a Balclutha woman with importing a class C drug following the execution of search warrants.
That swoop revealed the pair had half a kilogram of pentedrone, which had an estimated street value of $40,000 to $60,000, Detective Senior Sergeant Malcolm Inglis, of Dunedin, said.
Figures released to the Otago Daily Times from the New Zealand Customs Service revealed it was only the second time in 18 months the drug had been intercepted.
''While we haven't seen a lot of pentedrone, the importation methods and risks are the same as with any psychoactive substance,'' a Customs spokeswoman said.
Psychoactive substances were continually evolving in chemical composition and posed ''a real health danger to consumers who are taking untested and potentially deadly products''.
Customs had been cracking down on importers of such substances, intercepting up to 15 suspected psychoactive substances each week, mostly through mail and air freight.
In the Dunedin and Balclutha case, the contraband was detected at the International Mail Centre in Auckland, which uses X-ray screening, detector dogs and intelligence to screen for illicit drugs.
''Customs continues to develop its intelligence picture of psychoactive substances and shares information with other law enforcement partners and overseas administrations, to support collaboration and to disrupt the supply chain,'' the spokeswoman said.
Toxicologist Dr Leo Schep, of the Dunedin-based National Poisons Centre, said pentedrone was often referred to by a street name given to other, similar, synthetic analogues - ''bath salts''.
These types of drugs were often passed off as MDMA (ecstasy) and could be swallowed or crushed up and injected.
While there were few reported cases in New Zealand of abuse of the drug, it had been raised as a cause of concern across the Tasman.
Last year, Glenn Punch (44) injected the drug with his girlfriend and the truck driver died two days later in an Australian hospital following a deep psychosis.
