Why 20mg Losec, 40mg Nexium?

[Jasmine]

I read that for Losec (omeprazole), 20mg is the normal dose. However, I think that for Nexium (esomeprazole), 40mg daily is the normal dose. Is this true and why would it be?

[daw]

Though they are similar PPIs, they have a slightly different chemical makeup. I'm sure someone can explain this for us in more detailed terms.

Also...Notice that the H2Blockers are dosed differently. Pepcid 10mg , Zantac 75mg, etc.. It does not mean that one is stronger than the other although one may work better than the other for some people.

Just to confuse things, some people eventually go on a maintenance dose of Nexium 20mg.