Sen. Grassley, the top Republican on the Senate Finance Committee, has continued his work to identify possible ties between drugmakers and doctors and now is looking into possible ghostwriting practices of major pharmaceutical companies, as well.

Sen. Grassley asked the medical writing company to provide details including payment for the articles on Prempro and the involvement of scientist who signed them. In the letter to Wyeth Chairman and Chief Executive Bernard J. Poussot, Sen. Grassley asked the drugmaker for information involving payment to study authors and to DesignWrite. The letters are part of a continuing investigation by Sen. Grassley into drug industry influence on doctors.

“The ghostwriting issue is important because it concerns the integrity of the scientific views expressed in medical journals,” Sen. Grassley said in a statement. “Shedding light on the relationships between drug companies and authors helps establish accountability and safeguard the credibility of influential medical journals.”

It appears that Wyeth executives prepared outlines for ghost-written articles, arranged the writing and found medical journalists to put their names to them.

Wyeth makes the hormone replacement drugs Prempro and Premarin. Premarin, an estrogen replacement, and Prempro, a combination of estrogen and progestin, are prescribed to women to ease menopause symptoms. Since 2002, sales of Prempro have dropped from $2 billion a year to a little more than $1 billion. Women went off their pills, choosing to risk hot flashes and brittle bones rather than heart attacks and breast cancer. A recent study concludes that after 2 years of hormone treatment, overall cancer risk remains about 24 percent higher for women who stopped taking a popular estrogen-progestin combination compared with those who took placebo pills.