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Pharmacological particulars
Pharmacotherapeutic group: Antibacterials for intramammary use, Beta-lactam antibacterials, penicillins, for intramammary use, Combinations of penicillins and / or beta-lactamase inhibitors.
ATC Vet Code: QJ51CR50
Pharmacodynamic properties
Contains ampicillin and cloxacillin, which are both beta-lactam antibiotics. Their structures containing the same beta-lactam ring and thiazolidine ring common to all penicillins.
Beta-lactam antibiotics prevent the bacterial cell wall from forming by interfering with the final stage of peptidoglycan synthesis. They inhibit the activity of transpeptidase enzymes, which catalyse cross-linkage of the glycopeptide polymer units that form the cell wall. They exert a bactericidal action but cause lysis only of growing cells. The difference in susceptibility between Gram-positive and Gram-negative bacteria depends on differences in receptor sites, on the relative amount of peptidoglycan present, on the ability of drugs to penetrate the outer cell membrane of Gram-negative bacteria and on resistance to the different types of beta-lactamase enzymes produced by the bacteria.
Ampicillin has a high activity against both Gram-positive and Gram-negative bacteria, but is inactivated by beta-lactamases.
Cloxacillin is relatively resistant to staphylococcal beta-lactamases but is of lower activity than penicillin G against susceptible Gram-positive bacteria and is inactive against Gram-negative bacteria.
The combination of penicillinase-resistant penicillins, such as cloxacillin, with ampicillin, against common opportunist Gram-negative bacteria, has shown synergism in many cases.