Identification of 10, 11-epoxide and other cyclobenzaprine metabolites isolated from rat urine

Cyclobenzaprine (40 mg/kg ip) was administered to rats, and six urinary metabolites of this drug were identified. They were the 10, 11-epoxide, the N -oxide, the desmethyl derivative, the hydroxylated and desmethylhydroxylated compounds, and the N-oxide hydroxylated at the 10- or 11-position. Mass spectrometric analysis confirmed their structures.