Ideally, the name of your New Drug should start with X, because hardly anything starts with X, and therefore you’re less likely to run into trademark difficulties. Unfortunately, hardly anyone knows how to pronounce an initial X, so the next best thing is something that sounds like an initial X but doesn’t look like one: in other words, a Z.
Of 1436 products added to the [British National Formulary] between 1986 and 2005, more than a fifth had names that began with z or x or contained a prominent x or z within them. In 1986, only 19 branded drugs began with one of these letters. Over the next two decades, the number of brands beginning with a z increased by more than 400% (to 63) and those beginning with an x increased by 130% (to 16). In the same period, the overall content of the BNF grew by only 80%.
Stepney explains this in terms of Scrabble:
[U]se of these letters relates to the imperative to make a brand name highly visible in a crowd. Reflecting their infrequent occurrence in English words, x and z count for 8 and 10 points in Scrabble, the highest values (along with j and q) in the game. So names that contain them are likely to seem special and be memorable. “If you meet them in running text, they stand out,” is the way one industry insider explained.
Of course, if everybody stands out, then no one stands out. Says the Neurocritic:
In my view, however, the rush to uniqueness resulted in an overcrowded field. The market became saturated with X and Z brand names, which can cause confusion.
As anyone who’s taken a Zantac instead of a Xanax can no doubt corroborate.
(Via this Nancy Friedman tweet. Cite: BMJ 2010; 341:c6895.)