Senator Tammy Baldwin (D-WI) sent letters this week to companies warning of improper Orange Book listings of patents for inhalers, following up on the FTC’s focus on potential anticompetitive harm of improper listings. According to Senator Baldwin’s letters, the recipients of the letters were warned by the FTC in November regarding the listing of inhaler patents, but have not removed the patents from the Orange Book. The letters follow an investigation launched earlier this month by the Senate Committee on Health, Education, Labor, and Pensions (of which Senator Baldwin is a member) into the prices of inhalers.