http://nypost.com/2016/07/29/drug-dealers-are-mixing-heroin-with-elephant-sedatives/
Perhaps you should educate yourself.
I'm highly educated. Drug dealers might be trying all sorts of new opiates in their mixes, but the notion that they "spike" a few samples of their product in order to deliberately cause overdoses is just silly.
No drug dealer wants the heat associated with overdose deaths, and they have plenty of customers for their product without having to resort to such tactics.
Believing every piece of "Reefer Madness" hysteria fomented by those conducting the Constitution-destroying and nanny-state-expanding Drug War doesn't necessarily constitute "educating" oneself...