XmasTM (brand substitution not permitted)

All independent sources of drug information use generic names, and prescribing by brand name has been a cause of a potentially fatal adverse drug event.1 Brand name prescribing is common at our hospital, despite a hospital policy mandating generic prescribing. There has been little published research on when and why brand names are preferred in prescribing. Although pharmaceutical companies give a range of reasons for devising certain types of brand names (eg, a short name, a name beginning in x or z),2 these appear to be based on unpublished market research. We explored the reasons behind the pharmaceutical industry’s choice of brand names by looking for factors that appear to contribute to use of brand names in prescribing.

We performed a retrospective study of prescriptions at the Canberra Hospital (December 2002 and February 2003). We reviewed the records of 600 admitted patients and recorded 1392 episodes of prescribing, using only data on the top 30 drugs prescribed in Australia, by volume.3

Faced with a choice of writing either “irbesartan/hydrochlorothiazide” (29 letters) or “Avapro HCT” (nine letters), most doctors opted for the latter. Only a Queenslander or someone excessively influenced by advertising would request “XXXX”, when they could be drinking “beer”. However, if people had to ask for (and the waiter had to write) “Humulus lupulus – Saccharomyces cerevisiae – ethanol – sucrose – water”, it is clear what would happen after a few orders. In the same way, more doctors might be encouraged to prescribe generically if generic names were devised with the same principles used by marketers for devising brand names.2

A common argument for prescribing by brand name is that it avoids patient confusion, as patients are most likely to use brand names for identifying drugs and usually have a poor knowledge of corresponding generic names.4 However, this is irrelevant in the hospital setting, as a cheaper generic drug is often substituted anyway, and nurses administer the drugs.

Other issues such as the quality and bioequivalence of generic substitutes are often mentioned.5 An understanding (as opposed to a concern) about bioequivalence was clearly not the issue in our study. Warfarin is the only drug on the list we reviewed for which bioequivalence between brands is a rational concern. However, of the 37 warfarin scripts reviewed, all were prescribed by generic name!

The x-factor is puzzling (perhaps a reflection that gender is usually unremarkable, but sex sells), as many drugs ending in x have had a stormy history — Bex (withdrawn due to analgesic nephropathy), Debendox (withdrawn due to birth defect litigation), Luvox (linked to youth suicide), Paradex and Capadex (removed from market in the United Kingdom due to possible cardiotoxicity), and Vioxx (withdrawn due to thrombotic adverse effects). In a recent review, six of 18 brand names with major United States Food and Drug Administration safety warnings ended in x.6

Perhaps an x should be regarded as a warning. It could be a graphical representation of how sales plummet as adverse reaction reports accumulate. Or it could simply be the final “kiss of death”.