Pharmacotherapeutic group: antibacterials for systemic use; amoxicillin and beta- lactamase inhibitor.
ATCvet code: QJ01CR02
Pharmacodynamic properties
Amoxicillin is an aminobenzylpenicillin from the β-lactam penicillin family which prevents the bacterial cell wall formation by interfering with the final step of peptidoglycan synthesis.
Clavulanic acid is an irreversible inhibitor of intracellular and extracellular β-lactamases which protects amoxicillin from inactivation by many β-lactamases.
Amoxicillin/clavulanate has a wide range of activity which includes β-lactamase producing strains of both Gram-positive and Gram-negative aerobes, facultative anaerobes and obligate anaerobes.
Specific veterinary clinical breakpoints have not been established. Human derived breakpoints (M100-S document) for amoxicillin/clavulanic acid are:
Organisms other than Staphylococci: sensitive: MIC < 8/4 µg/ml, resistant: MIC > 32/16 µg/ml
In dog periodontal infections in Europe (isolates of the year 2002 from France, Germany and Belgium) amoxicillin/clavulanic acid combination in a ratio 2/1 showed the following data on sensitivity:
Pasteurellaceae: MIC90: 0.4/0.2 μg/ml,
Streptococcus spp.: MIC90: 0.4/0.2 μg/ml,
Escherichia coli: MIC90: 5.3/2.6 μg/ml,
Resistance to β-lactam antibiotics is mainly mediated by β-lactamases which hydrolyze antibiotics such as amoxicillin.
Susceptibility and resistance patterns can vary with geographical area and bacterial strain, and may change over time.
Pharmacokinetic particulars
After oral administration at the recommended dose in dogs, the absorption of amoxicillin and clavulanic acid is fast. The maximum plasma concentration of amoxicillin of 8.5 µg/ml is reached in 1.4 hours and the maximum plasma concentration of clavulanic acid of 0.9 µg/ml is reached in 0.9 hours. Half-life is 1 hour for both substances.
Elimination is also fast. 12 % of the amoxicillin and 17 % of clavulanic acid is excreted in the urine. The remainder is excreted as inactive metabolites.
After repeated oral administration of the recommended dose, there is no accumulation of amoxicillin or clavulanic acid and the steady state is reached rapidly after first administration.