October 10, 2012

Classification problems

I was interested in how the new psychoactive substances laws were going to handle the problem of, on one hand, the unsafe legal highs that they don’t want to ban, and on the other hand, the potentially psychoactive substances that they don’t want to have to regulate.  Safety testing for new medications is a complicated scientific and statistical problem and hard to get right even when you aren’t trying to gerrymander it.

The regulatory impact statement says they are just going to do all this by fiat. Alcohol, tobacco, caffeine (and presumably kava) will be exempted so they can be handled by existing law; currently-banned drugs will still be banned;  and things like nutmeg and a range of ornamental plants will be classified by fiat as not psychoactive if anyone raises the issue.  In the case of any ambiguity, the regulator will get to just decide. I suppose that’s the only practical way to do it, given the goals.

The headlines so far have been about the cost of approval, which is about twice what MEDSAFE charges for new medications. That’s  not unreasonable considering that legal highs are likely to be less chemically and biologically familiar than most medications.  However, the costs are basically irrelevant unless the safety criteria are written loosely enough that some psychoactive compound could conceivably pass them.  Since the criteria don’t have to be consistent with any of the rest of drug and food laws, and it’s unlikely that anyone will come up with the testing budget, there’s no upside to making them realistic.

It will still be interesting to see how the criteria end up being written, and whether caffeine, nutmeg, (or, in the other direction, some cannabis preparation) would be able to pass them. Obviously alcohol and tobacco wouldn’t.

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »