Just call it the Energizer Bunny. Despite drawing fire from consumer groups, legislators and other concerned critics wanting to curb it, direct-to-consumer pharmaceutical advertising keeps on going. Yet promotion to professionals still draws the lion's share of promotional spending, according to a study in The New England Journal of Medicine.

Total spending on DTC advertising in the US increased from about $1 million in 1996 to $4 billion in 2005. Yet only 14% of total industry expenditures on pharmaceutical promotion were devoted to DTC advertising in 2005, the study found. As a percentage of sales, it was only 2.6%.

While investments in detailing and journals ads have dwindled in recent years, personal selling and free samples still command the biggest chunk of the promotional budget, accounting for some $25 billion. (For samples the figure is calculated by retail value.) When journal adverts are factored in, that's about 86% of spending.

Some drugs in top-selling classes, such as antidepressants and antipsychotics, are promoted mostly via reps. As for which drug categories relied heaviest on DTC, they found that DTC consumed about a third of the budget for proton-pump inhibitors,statins and erythropoietin drugs.

They also noted a dramatic dip in the number of FDA regulatory actions regarding DTC advertising in recent years, from 142 in 1997 to only 21 in 2006, reflecting either better industry compliance—due perhaps to the voluntary PhRMA code—or worsening FDA oversight. The level of FDA staffing dedicated to review of DTC advertising has not kept pace with the recent increase in DTC advertising, authors stated. From 2002 to 2006, DTC advertising was the target of one third to one half of drug promotion violation letters sent by the FDA. Most violations involved DTC advertising that minimized risks or exaggerated effectiveness.

As most companies begin ad campaigns within a year of drug launch, any mandatory restrictions on consumer advertising, such as a DTC moratorium, would be a major shift for most marketers, the researchers added.