The office of inspector general of the Department of Health and Human Services is conducting a "preliminary inquiry" into allegations that the White House may have exerted pressure that influenced approval of a new surgical suture device, a department spokesman said yesterday.

A presidential spokesman also confirmed that a White House aide had called the Food and Drug Administration because of interest on the part of Nancy Reagan's stepfather, Dr. Loyal Davis, a retired neurosurgeon who has been a longtime consultant to the company seeking approval of the suture.

Assistant press secretary Mark Weinberg said the contact was a "routine inquiry." He maintained that "the White House never recommended, requested or suggested any action whatsoever" and that "absolutely no" pressure was intended.

Last Friday, the FDA granted approval for the "PDS" surgical suture --a dissolving thread made of a synthetic known as polydioxanone--to Ethicon Inc., a subsidiary of Johnson & Johnson of New Brunswick, N.J.

FDA spokesman Wayne Pines said the decision was based on "science," not "pressure." He acknowledged that White House inquiries last spring were "not common" but said the calls "had no effect on the approval process or the speed with which the decision was made."

J&J spokesman James Murray said any action by Davis, a prominent physician who has been a company consultant for 18 years, was "purely at his own initiative . . . . Ethicon has never requested that anyone attempt to obtain preferential treatment for PDS suture," which has been awaiting approval since 1979.

Davis could not be reached for comment.

Questions about the approval were raised by the Health Research Group, a Ralph Nader-backed public interest organization, and reported by States News Service and Clinica, a medical trade publication .

In a letter to FDA Commissioner Arthur Hull Hayes Jr. in late September, the Nader group said "unseemly and possibly illegal pressure" may have been exerted and cited unresolved safety questions.

Allen Greenberg of the Nader group expressed concern yesterday that the FDA had approved the suture, disregarding the group's questions and a September request by FDA's advisory panel for conditional approval pending further testing.

"I think that the people at FDA were under tremendous pressure to approve it quickly. Part of the pressure may have been the result of those calls," he said.

Senior attorney Barry Sax of the HHS inspector general's office said he began a few weeks ago "looking into" questions raised by the Nader group, after the matter was referred by Hayes. Robert Wilson, a spokesman for the inspector general, said that there was a "preliminary investigation under way to establish the facts, which is distinct from a full-fledged investigation which might go to the U.S. attorney."

White House spokesman Weinberg said Davis had simply asked for a "status" report on the suture approval in a "casual conversation" earlier this year with Michael K. Deaver, Reagan's deputy chief of staff. Weinberg said Deaver contacted the White House office of Cabinet administration, which asked then-intern Susan Sims to call FDA.

FDA memoranda confirm two convervations on May 5 and 7 with officials in the Bureau of Medical Devices. Sims, reached by The Washington Post in Los Angeles yesterday, said she had then prepared a "fact sheet" on the status of the suture application.

Weinberg said he did not know what happened to the "fact sheet" but that the information was not passed to Davis. He said that "to my knowledge" Deaver was not aware Davis was a consultant to the manufacturer of the suture.