The topic of “me too” drugs has come up quite a bit around here over the years. For the most part, I’m a defender, although there are some places I draw the line (Clarinex for Claritin comes to mind as a particularly useless advance). A reader pointed out the amount of advertising he’s seeing for Aciphex (rabeprazole), another proton pump inhibitor for gastrointestinal reflux and general stomach acid problems, and wonders what side of the line this one is on.

I’m already on record as wondering just how much of an advance Nexium (esomeprazole) was over its racemic form, Prilosec (omeprazole), so the bar is set pretty high in this area already. Looking through PubMed, I find numerous comparisons between the drugs, which suggest some small differences in PK. Some earlier studies suggested that rabeprazole works more quickly over a course of therapy, but this is in dispute. There do seem to be differences in drug interactions between the various drugs in this category, which could be important in older patients who are already taking other medications. (Protonix (pantoprazole) may also be in this category). Perhaps reflecting this, this study found that rabeprazole was "significantly more effective" in elderly patients.

So, overall, there do seem to be some differences between the various drugs in this category (summarized here, among other places). In most cases, though, they're pretty much the same. This looks like a fight among near-equals, with the occasional tiebreaker going to one compound or another. This would explain why the ads for the various compounds are pretty interchangeable as well, featuring people holding their stomachs when confronted with a plate of barbecue. (Living in the Boston area, I can understand that reaction to some of the local stuff, but that's another topic).

As I say, I generally defend the idea of several drugs entering the same therapeutic space. In theory, and for the most part in practice, each new entrant provides something that the previous ones didn’t, and can thus carve out a space for itself. In this case, though, the differences between these drugs, though real, are comparatively small and subtle. There are patients who benefit from the number of choices in this category, but not as many as the advertising dollars would suggest. The whole proton-pump inhibitor market seems to be a fight among near-equals to carve up a large and lucrative market. The parallels that occur to me are the markets for SUVs and laundry detergent.

That means that it's a fight made for the big companies, for one thing. A smaller outfit would have been crazy to get into the PPI arena without a big partner. Given the current state of the art, it would seem crazy for anyone else to be contemplating an entry at all, unless they have some huge advance that they can demonstrate clinically. The existence of so many PPIs is not a scandal - yet - but it's not a glorious chapter in the history of drug research, either.