Congressional investigators are probing drug maker Wyeth's scientific-paper writing practices, specifically concerns that its marketing employees help shape manuscripts for medical journals.

Senator Charles Grassley asked the company to disclose payments he said were made to prepare certain articles, and for information about how doctors were recruited to place their names on those articles. The articles, published in peer-reviewed medical journals, involved Prempro and other female-hormone-replacement therapies made by Wyeth.

The inquiry comes as part of the Senate Finance Committee's examination of "medical ghostwriting," which is itself part of a broader probe into the influence of drug companies on the health-care industry.