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The amoxicillin 500 contains only one medication, the amoxicillin, in a strength of 500 mg in every tablet.
The Amox tr K clv is a combination of 500 mg of amoxicillin (exactly as in the other pill you mentioned) along with 125 mg of clavulanic acid.
Clavulanic acid does not kill bacteria like the amoxicillin does but, rather, it makes the amoxicillin work better against certain types of bacteria (beta lactamase producing). In other words it makes amoxicillin work better against some bacteria that might otherwise be resistant.
So. What is the take home message here? Both medications contain the same "strength" of the active ingredient (amoxicillin) but the Amox tr K clv, has a compound in it to extent the number and types of bacteria that can be killed by amoxicillin.
As long as the bacteria that you are trying to treat do not secrete beta lactimase, both drugs will work essentially the same.
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