In this case, the literary function of the word "like", is used as a conjuction, or
"...like [as in] heroin, cocaine and marihuana?" Perhaps you're thinking of the word "liken", meaning, to compare. Something you should have learned in third grade. Plain and simple, this is about lumping three drugs together, as dangerous substances. This has absolutely nothing to do with pharmacological properties and shared relationships.
More foolish talk from another pro-doper!