As if to teach the rest of us a lesson in true Scottish thrift, Irvine Welsh has wrung a wide variety of uses from the material in Trainspotting, his celebrated 1993 novel about Edinburgh heroin addicts. There’s the stage adaptation by Harry Gibson. And the movie, famously directed by Danny Boyle. Welsh released his own literary sequel, Porno, in 2002. And his 500-odd-page prequel, Skagboys, came out just last month.

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The “American landscape” turns out to be Kansas City, MO. Welsh’s little clan of dopers, dropouts, and sociopaths speak with midwestern twangs, work (when they work) at the local big-box outlet, and play basketball as opposed to soccer. Their brush with big-time drug lords takes place down Mexico way rather than in London. But beyond these trappings, things fall out pretty much as they do in the original tale. The narrator and main character, Mark, is a paradoxically wholesome junkie whose struggles to get and stay clean structure the action. He’s surrounded by picturesque lowlifes like cunning Simon, simple Spud, empty Alison, and homicidal Begby.

Still, iconic as they are to any fan, none of these vignettes carries any real weight in Mullen’s version. The Hippocratic command to do no harm should apply to adapters every bit as much as it does to physicians; Mullen violates it over and over again, in ways big and small (though apparently not without the author’s permission, since Welsh is credited with having provided “new material”).

Through 12/2: Thu-Fri 8 PM, Sat 7 and 9 PM, Sun 5 PM, Theater Wit, 1229 W. Belmont, 773-975-8150, theaterwit.org, $32.50.