A synthetic drug known as "coma in a bottle" has become more common in the Western Bay of Plenty.
The disclosure comes after Waikato police this week uncovered a laboratory in Huntly producing the drug gamma-butyrolactone (GBL) - possibly the country's first such manufacturing operation.
Four Waikato men have appeared in court on charges relating to the manufacture of the drug, considered a potential date-rape drug.
The liquid chemical was originally produced as a paint stripper and rust remover before being introduced to the party scene, where its effects in small quantities have been likened to the high from ecstasy.
In higher doses, however, GBL has been used as a date-rape drug, causing those who drink the chemical to experience blackouts or become sleepy and disorientated.