The drug, which in its powdered form is sold as a plant fertiliser in Britain and used as a substitute for ecstasy, has been linked to several deaths in the UK and one in Sweden.
British police said mephedrone contributed to the deaths of Louis Wainwright (18) and Nicholas Smith (19), who died on Monday, The Times in London reported.
In New Zealand, mephedrone is classified as a Class C drug, and carries a maximum sentence of eight years for persons convicted of supply; and three months' jail or a $500 fine if found in a person's possession.
Mephedrone is also banned in Norway, Finland, Denmark, Israel and Sweden.
Figures released to the Otago Daily Times show 15 packets of the drug were intercepted at the border by the New Zealand Customs Service since November 13, with six packets destined for Dunedin, and one for Wanaka.
All packets destined for Otago addresses and intercepted at the Auckland Mail Centre came from the United Kingdom via mail, with both registered mail services and Express Mail Service used.
The Dunedin-addressed packages were intercepted between January 10 and 21, with each containing 10g, and were believed to have a street value of more than $200.
Auckland accounted for five interceptions, with the largest consignment, 450g, sent to Nelson from China on November 18.
Customs drug investigations manager Mark Day said the service was reviewing its approach to mephedrone after increasing imports, and websites advertising the product.
"Customs is aware of reports on the internet about New Zealanders using mephedrone as a substitute for ecstasy. However, the levels this is occurring [at] is very difficult to quantify."
All the seized drugs were destroyed, and investigations involving several agencies were under way.
Southern District Intelligence manager Inspector Steve Kelly said police were aware of the interceptions, but he was unaware of any cases involving the use of the drug being reported locally.
"But we are looking at it now, because it has come up pretty quickly."
National Poisons Centre medical toxicologist Dr John Fountain, of Dunedin, said although the centre was aware of the presence of the drug, it was too early to determine its impact.
"It looks like it is one of those that might be on the increase."
Mephedrone, which was a hallucinogenic amphetamine, was potentially dangerous if taken in large doses, he said.
MEPHEDRONE
• Designer drug also known as "m-cat" , "meph", and "meow".
• Classified in New Zealand as a Class C drug.
• Sale or supply illegal in New Zealand.
• Sold in United Kingdom as plant food.
• Can be fatal: one confirmed mephedrone-related death in Sweden and others suspected in the UK.
• Side-effects include anxiety, paranoia, vomiting, nose bleeds, hallucinations, nausea, rashes and seizures.
SOURCE: SUPPLIED
