Watch a drug advertisement in the US-any one, really-and one thing you're unlikely to hear any mention of is the drug's cost.

That's not always an accident, as the myriad of insurance companies, co-pays, state insurance programs, private assistance programs, coupons and other incentives mean that the true cost of a drug is rarely seen by consumers and is rarely the same for two people.

But assume, for a moment, that such an instance existed-that a drug ("Drug A") cost the exact same amount to every consumer, and that it offered no coupons, discounts, or any other incentives.

Now assume that the drug has a competitor, a drug  ("Drug B") approved for the same condition and which costs twice as much despite possessing a safety and efficacy profile that is almost identical to Drug A.

Could Drug A advertise itself as having a cost advantage relative to Drug B?

Proposed Study

The question is the subject of a new Federal Registerannouncement issued by the US Food and Drug Administration (FDA), which says it wants to answer a few nagging questions about how cost data makes its way into direct-to-consumer advertising.

"Currently, when price comparisons are made, the ad should also include context that the two drugs may not be comparable in terms of efficacy and safety and that the acquisition costs presented do not necessarily reflect the actual prices paid by consumers, pharmacies, or third party payers," FDA explains in the notice.

Despite that requirement, FDA says it's not convinced that consumers are necessarily paying attention to those disclaimers, and that the price comparison may imply that the products are interchangeable.

To see if this is this case, FDA's Office of Prescription Drug Promotion (OPDP) says it plans to "investigate, through empirical research, the impact of price comparison information and additional contextual information on prescription drug product descriptions."

The research will focus on DTC advertising aimed at diabetes patients (and physicians who treat diabetes) estimated to represent the "average" consumer (i.e. not healthcare or marketing professionals).

The proposed studies of 400, 1,000 and 2,940 participants (respectively) will compare DTC advertising using the following study design:

FDA says it hopes the proposed study will take about 30 minutes on average to complete for each participant.

Federal Register Notice