Lansoprazol er koncentreret i parietalcellerne og bliver aktiv i deres syrlige miljø, hvorefter det reagerer med sulfydrylgruppen i H+/ K+ATPase, hvilket medfører hæmning af enzymaktiviteten.
Lansoprazole is concentrated in the parietal cells and becomes active in their acidic environment, whereupon it reacts with the sulphydryl group of H+/ K+ATPase causing inhibition of the enzyme activity.