A simple and sensitive spectrophotometric method is described for the
determination of cefadroxil and metyrosine in pure form and in pharmac
eutical formulations. The method is based on reacting these drugs with
4-aminoantipyrine (AAP) in the presence of an all:aline oxidising age
nt. The coloured products were measured spectrophotometrically at 500
nm and 470 nm for cefadroxil and metyrosine, respectively. Beer's law
was obeyed over the concentration range 1-28 and 2-44 mu g ml(-1) for
cefadroxil monohydrate and metyrosine, respectively. The molar ratio i
n both cases was established and a proposal for the reaction pathway w
as suggested. The percentage recoveries obtained were in accordance wi
th those given by the reference methods.