Both drugs are cardiotoxic and nuerotoxic by the same mechanisms, they both put more seratonin and dopamine into a synapse so they're inherantly nuerotoxic. In case you didn't know when your seratonin is no longer releasing and is reabsorbed dopamine is oxidized and harms seratonin receptors (how MDMA and mephedrone harm your brain). Doing mephedrone on top of doing MDMA would pump a lot more dopamine and release a smaller ammount of seratonin, so more dopamine to oxidize. <-that's true for all dopamine releasors combined with MDMA though. What really worries me about mephedrone is the tachycardia it causes and for so long after. It honestly doesn't take long for even weekend use of mephedrone to catch up with you. I can't give you scientific facts on why because well were the lab rats and the results aren't in yet, but I can tell you that after doing it maybe seven times in a month me and two friends are feeling negative side effects, I know two other people who went to the hospital because it fucked with their hearts and I went to the hospital because it fucked with my heart. Don't take this shit lightly, combining it with another stimulant is just asking for problems. I know it's not gonna stop you, and hey you might have a great time that nightz. BUT keep in mind this shits
not safe. It's been known to turn peoples joints blue.... What drugs have you done that turn your knees blue and you think they're chill?
And FYI, out of around 15 people I know who have done drone more than once, 3 have been to the hospital for it.