The U.S. Food and Drug Administration said Tuesday it was requiring the manufacturers of certain drugs used to prevent the rejection of transplanted kidneys to warn of certain serious infections.

The drugs, which include Roche Holding AG's (RHHBY) CellCept, Myfortic by Novartis AG (NVS) and Wyeth's (WYE) Rapamune, already carried the agency's toughest boxed warning discussing their various risks.

The FDA said the new drug labels must discuss an increased risk of "opportunistic infections," including activation of latent viral infections such as one caused by the BK virus.

The FDA said such infections may lead to serious outcomes, including kidney graft loss.

-By Jennifer Corbett Dooren, Dow Jones Newswires; 202-862-9294; jennifer.corbett@dowjones.com

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