> the drug manufacturer mislabeled the MDMA bottle as Methamphetamine, a much more damaging drug
It's not even so much that (comparing two drugs like that doesn't really make sense). It's that the dosage administered was far more than what would be comparable for methamphetamine. 6 mg/kg of one drug is not necessarily comparable to 6 mg/kg of another drug... 300 mg of methamphetamine for a ~110 lb. person over 9 hours is absurd - the maximum prescribed dose of Adderall (d-amphetamine) is generally 40-60mg per day, and that's only for individuals with high tolerance (or very severe problems such as narcolepsy). These are oral dosages, mind you, whereas the study used subcutaneous injection, which amplifies the effect of the drug further. Then account for the fact that methamphetamine crosses the blood-brain barrier more easily than its cousin that lacks the methyl group, and you start to wonder why only one of the five monkeys died.
Even before they realized the drug mixup, the Ricaurte, et. al. study is so flawed that it's almost laughable that it was published in the first place. Your study is intended to simulate the environment of a club/rave? 20% of your subjects died after what you considered to be a moderate dose, and you didn't think that was cause to question your methods? Raves may not be the healthiest places in the world, but if real life were anything close to what those data suggest, the morning after a concert or rave you would find the floor literally covered in dead bodies.
I won't even get into the absurd conclusions that they draw from their measurements themselves, since this is HN, not a neuroscience forum, but suffice to say that any college freshman in an introductory neuroscience class should have known better. It's as if they copied and pasted the analysis from another study and inserted their own data into it - that's how nonsensical it is.
The retraction for Ricaurte, et. al.: http://www.pages.drexel.edu/~ls39/peer_review/Ricaurte_retra...
(The original study is linked from the retraction page; I'd emphasize again that the study itself had enough other flaws in it that it should never have been published in the first place, even if the drug mixup had never been discovered).