Media/Analyst Viewpoint The pain reliever Duexis is a combination of two old drugs, the generic equivalents of Motrin and Pepcid. If prescribed separately, the two drugs together would cost no more than $20 or $40 a month. By contrast, Duexis, which contains both in a single pill, costs about $1,500 a month. Needless to say, many insurers do not want to pay for Duexis. Yet sales of the drug are growing rapidly, in large part because its manufacturer, Horizon Pharma, has figured out a way to circumvent efforts of insurers and pharmacists to switch patients to the generic components, or even to the over-the-counter versions.