Manufacturers receiving warning letters Tuesday are: Boehringer Ingelheim Roxane Inc. of Columbus, Ohio; Cody Laboratories Inc. of Cody, Wyo.; Glenmark Pharmaceuticals Inc. of Mahwah, N.J.; Lannett Co. Inc. of Philadelphia; Lehigh Valley Technologies Inc. of Allentown, Pa.; Mallinckrodt Inc. Pharmaceuticals Group of St. Louis; Physicians Total Care inc. of Tulsa; Roxane Laboratories Inc. of Columbus, Ohio; and Xanodyne Pharmaceutical Inc. of Newport, Ky. The largest, Boehringer, didn't immediately return a call seeking comment. Even FDA-approved versions of these painkillers pose a risk of serious side effects, but the unapproved products add an extra problem: Regulators haven't checked that those versions work as well and are as pure as their approved competitors.