U.S. Food and Drug Administration Acting Commissioner Lester Crawford on Friday agreed to meet with a top Republican lawmaker about the agency’s handling of safety concerns over Merck & Co Inc.‘s now-withdrawn painkiller Vioxx.

In a letter to Senate Finance Committee Chairman Sen. Charles Grassley, Crawford said he took the Iowa Republican’s concerns “very seriously,” without specifically referring to the lawmaker’s fears for FDA whistle-blower David Graham.

The agency “strives to facilitate a meaningful dialogue between employees at the agency and committee staff,” according to a copy of Crawford’s letter obtained by Reuters.

Merck pulled Vioxx from the market in September after studies showed an increased risk of heart ailments and sudden death from the arthritis drug.

Graham, associate director for science in the Office of Drug Safety, testified at a Nov. 18 hearing called by Grassley on Vioxx.

Graham accused the agency of being unable to protect the public and named five other drugs he said were a concern and should be withdrawn or carefully scrutinized.

FDA officials have defended the agency’s work and said the five drugs were no more concerning than others on the market.

Grassley has sent two letters to the FDA seeking to protect Graham, who has said he felt intimidated by his superiors and has sought legal protection from a whistle-blower group - the Government Accountability Project.