And thus it begins: Xyzal

The money being wasted on pointless research, that is. Xyzal (levocetirizine), is beginning to have some money spent on research proving that it's a good drug. I have no doubt it's a good drug. They've isolated the active isomer and decided to market it since the patent on Zyrtec (cetirizine) is running out.

Let's review, SAT-style:

Zyrtec:Xyzal::Claritin:Clarinex

Expect Zyrtec to go OTC as a means of ensuring continued profitability through marketing. (More people buy brand name Tylenol than the generic — same story for Claritin.)

Here's the bottom line: everything that Zyrtec works for, Xyzal will work for, and vice versa. Same side effects, too. And because this is so, you will never see a head-to-head study comparing Xyzal with Zyrtec, because the results will prove that it's just a waste of money. Like Clarinex. Oh sure, there will be a few isolated cases where Xyzal is 0.5% better for 0.1% of the study population, and these studies will be trumpeted, but remember that they're actually meaningless. You'll also see studies that show Xyzal is effective for some obscure condition that Zyrtec was never studied for. Just remember that this is done to make Xyzal seem like something more than a me-too drug, and that if someone bothered to spend the money, Zyrtec would work just as well.

So if you like to waste your time doing PAs or you feel an insane need to throw your patients' money away, prescribe Xyzal. Otherwise keep on using Zyrtec.