“ Cimetidine , which inhibits cytochrome … with the heme iron , significantly blocked iron release, whereas ranitidine, which has a similar structure as cimetidine but is a weak inhibitor of P-450, … effect (H2O2, 0.42 +/- 0.04; H2O2 + cimetidine, 0.23 +/- 0.02 nmol/mg protein; N = 4, P < 0.01).”