Amoxicillin:

The mechanism by which β-lactam antibiotics bind with proteins associated with developing the bacterial cell wall, resulting in the ultimate lysis of the cell is well established. In the case of Gram-positive bacteria the β-lactam can freely pass across the peptidoglycan layer in the aqueous phase to the site of activity at the cytoplasmic membrane. In the case of Gram negative bacteria there is a hydrophobic barrier outside the peptidoglycan layer. Broad spectrum β-lactam antibiotics have the ability to cross this barrier by way of small pores in its structure.

There are three major mechanisms of resistance available to bacteria: the production of β-lactamase enzymes, impermeability of the cell wall by modification of the small pores and by modification of the amino acid sequences at the cytoplasmic membrane interface where the cell wall is constructed.

Clavulanic acid:

In the absence of specific inhibitor enzymes with β-lactamase activity, β-lactamases either form complexes with the antibiotic or cause a breakdown of the β-lactam ring. In either case the antibacterial activity is lost.

Clavulanic acid has a β-lactam ring in its structure which is recognised by β-lactamases as a type of “penicillin”. The enzyme/clavulanate interaction is irreversible and the results in the depletion of enzymes molecules.

Following either subcutaneous or intramuscular administration of Synulox RTU to dogs and cats, and intramuscular administration to cattle and pigs, both amoxicillin and clavulanic acid are well absorbed and well distributed in the tissues. The major route of elimination of amoxicillin and clavulanic acid is via the urine.