This is a popular drug in the UK which has caused a number of deaths due to its toxicity.  PMMA or Superman was created as a alternative for ecstasy.  Although it is currently predominantly in the UK, it can be found in the US and is likely to increase in usage here as well.

“The main effect of MDMA is to boost serotonin and dopamine levels, the feel-good chemicals in the brain. In contrast, PMMA blocks an enzyme that normally breaks down serotonin. The difference matters. The brain on PMMA cannot get rid of serotonin as fast as it should. Take enough and the drug induces serotonin syndrome, an overdose of serotonin that can lead to overheating, brain and vascular damage, and death.

Because PMMA can take two hours to have an effect, people take more. “They think they’ve had a dud pill so they take another one. And that puts them into a massive overdose,” Nutt said.”