Clavulanic acid is an antibiotic, which selectively blocks the betalactamase enzyme. So the amoxicillin is left free to kill the bacteria, which produce betalactamase enzyme. For this advantage, clavulanic acid is added with amoxicillin.
The drug Augmentin, for example, contains a combination of amoxicillin and a betalactamase inhibitor, clavulanic acid.
ceftriaxone is ase third genration antibiotic and having good coverage againast gram positive and grame neative ,while sulbuctem increase its activity against betalactamase producing bcteria.
amoxy and clav are combine together to take care bacteria who is producung an enzyme called beta lactamase. this enzyme attacks Beta lactum ring in amoxy and destroys the efficacy of Amoxy. to protect amoxy from betalactamase clavulinic acid is combine which is responsible to take care of this enzyme and ensures efficacy of amoxy .Clav in combination has no antibacterial action madhv deshpande