Synthesis of C-13-Lidocaine as a Probe of Breath Test for the Evaluation of Cytochrome P450 Activity

C-13-Labeled lidocaine, 2-di[1-C-13]ethylamino-N-(2,6-dimethylphenyl)acetamide (1), was synthesized from [1-C-13]acetic acid in six steps, as a probe for a breath test to evaluate in vivo cytochrome P450 activity. The measurement of (CO2)-C-13 in breath was successfully performed following oral administration of C-13-lidocaine 1 to mice.