Marc-André Gagnon and Joel Lexchin from York University in Toronto, Canada, have ploughed through data from two market research companies (IMS and CAM) and found that US drug companies spent $57.5bn (€39bn) on promotional activities in 2004, the latest year for which figures were available.
In addition, Gagnon and Lexchin think the marketing figure is likely to be an underestimate.
"There are other avenues for promotion that would not be captured by either IMS or CAM," they said.
These include the ghost-writing of articles in medical journals by drug company employees, or the off-label promotion of drugs.
Even if not, the value dwarves the $31.5bn that the National Science Foundation reported was spend on industrial pharma research and development in the same year.
That also includes public funds for R&D within the industry.
The pharma industry likes to remind the public how much they spend on R&D at every available opportunity and the authors contend that it promotes itself as "research-driven, innovative, and life-saving" .
Meanwhile, critics say the drug industry is based on "market-driven profiteering ".
Which of those two viewpoints is the more accurate is constantly a topic of hot debate in the media but Gagnon and Lexchin believe the findings of their study "confirms the public image of a marketing-driven industry and provides an important argument to petition in favour of transforming the workings of the industry in the direction of more research and less promotion."
The types of promotion that were included in the $57.5bn figure included free samples, visits from drug reps, direct to consumer advertising of drugs, meetings with doctors to promote products, e-mail promotions, direct mail, and clinical trials designed to promote the prescription of new drugs rather than to generate scientific data, which are known as 'seeding trials'.
The full article: "The Cost of Pushing Pills: A New Estimate of Pharmaceutical Promotion Expenditures in the United States" is available online from the latest issue of PLos Medicine .