Celecoxib, atorvastatin, and their metabolites in mouse serum. Male SCID mice (10/group) were fed AIN76A diet containing 0.05% celecoxib, 0.02% atorvastatin, or 0.05% celecoxib+0.02% atorvastatin for two weeks. Serum samples were collected on the last day of the experiment and analyzed for the levels of celecoxib, atorvastatin, and their metabolites. (A) HPLC chromatogram of the parent compounds and metabolites. (B) MS2 spectra and structural elucidation of deprotonated ions from celecoxib, atorvastatin, and their metabolites.