The Relative Rates of Formation of the Phenolic Metabolites of Mepivacaine in Man

The relative rates at which the two phenolic metabolites of mepivacaine, 1-methylpipecolo-3′-hydroxy-2′,6′-xylidide and 1-methylpipecolo-4′-hydroxy-2′,6′-xylidide were excreted in the urine in man varied as the interval between administration and urine collection increased.2. Initially the 3′-hydroxy metabolite was excreted in higher concentration but by the end of the collection period (24 h) the 4′-hydroxy metabolite was present in higher concentration.3. The biological and chemical evidence presented is consistent with the proposal that the 3′-hydroxy metabolite arises from an epoxide intermediate and that the 4′-hydroxy metabolite arises by rearrangement of an N-hydroxy intermediate.