Chemjobber drew my attention to this a few days ago, rightly noting that someone was indeed falling for a big ol’ pile of hype. There’s an awful lot of breathless stuff out there about “3-D printed drugs”, and this will serve as a fine example. Many of these pieces suffer from one or more of these errors
Confusing a drug with a formulated dose of a drug. That was the case with the press reports back in August. It’s certainly reasonable to imagine spraying down layers of a known drug along with excipients and other formulating agents until you get up to a useful dosage, but too many of these reports seem to think that the “printer” is somehow synthesizing the drug.
Not understanding what organic synthesis is. If you were to design some sort of 3-D printer thingie to make a new compound, how exactly would that work? This confusion was greatly added to by the publicity around the Burke synthesis machine, which (although very interesting) was nothing of the kind. Most reactions need reagents, and most of them need solvents, and many of them need controlled temperatures and other conditions. How is spraying things out of a tiny nozzle going to accomplish all these? The closest thing I can imagine is some kind of flow chemistry reactor whose output (or the output of an associated LC system) is then sort of spray-dried onto a surface. But that process will have to be carefully optimized each time if you’re going to use it, and you’ll have to have a good reason for going to the trouble. The article I’m linking to today slides from formulations to de novo synthesis without even so much as a missed step, but they’re very different things:
The technology could, in theory, allow users to print drugs of any size, shape, and dosage with ease. All they’d need is a downloadable recipe, basically a set of instructions that the printer reads and follows. As long as their home printer is stocked with the necessary base compounds, they could synthesize any and every formulation they’d need. It’d be just like using recipes from a cookbook, only it’d take only half as much work. . .
“The necessary base compounds” – that’s the tricky part. Are those the active drugs themselves? You’re going to keep a whole variety of those around in your Drug-o-matic Printer in case you’re prescribed one of them? How big is this thing supposed to be, anyway?
Overestimating what we know about drug delivery, and how hard it is to know it. This article (as above) blithely talks about whole lists of formulations, tailored to every patient. But the number of formulations for any given drug is often rather shorter than that, and that’s because every time you change one you have to take it into a bunch of patients and carefully make sure that it’s doing what it’s supposed to do. You can, in fact, totally screw up a useful drug’s effects by formulating it wrongly. The time and effort it takes to come up with good formulations means that there’s not going to be some sort of screen with three or four sliders on it, all of which can be varied to make something useful. And I haven’t even gotten into stability, polymorphs, and all the other wonderful things that makes that field such a joy.