Police have issued a warning about 'blue Superman' pills (pictured) in the Australian state of New South Wales after 11 people were hospitalised in the city of Newcastle, about two hours north of Sydney, last weekend.
The blue triangle-shaped pills featuring the distinctive logo are being sold as ecstasy, but experts are concerned about what the batch really contains, with results of tests carried out not yet known.
The Sydney Morning Herald reports Dr Craig Sadler, director of the drug and alcohol unit at Calvary Mater Newcastle and Hunter New England Health, said it was unclear what was in the drug at this stage.
"Clinical signs could indicate it contains a particularly potent dose of MDMA," he told the paper.
"But there are some signs not consistent with a stimulant, indicating it might not be MDMA but rather a central nervous system depressant.
"At this stage we don't know what's in them."
The paper reports the patients are understood to have declined rapidly with varying levels of consciousness and at least one suffered seizures.
They have since all recovered and been discharged from hospital.
Scott Carbines is Mixmag's Australian Digital Content Editor, follow him on Twitter