Natravox Mechanism of Action

Pharmacology: Pharmacokinetics: Absorption and Fate: Amoxicillin and clavulanate potassium are well-absorbed from the gastrointestinal tract after oral administration. Approximately 50-70% of the amoxicillin and approximately 25-40% of the clavulanic acid are excreted unchanged in urine during the first 6 hrs after administration of 10 mL of 250 mg/5 mL co-amoxiclav suspension.
Neither component of co-amoxiclav is highly protein bound; clavulanic acid has been found to be approximately 25% bound to human serum and amoxicillin 18% bound.
Amoxicillin diffuses readily into most body tissues and fluids with the exception of the brain and spinal fluid. The results of experiments involving the administration of clavulanic acid to animals suggest that this compound, like amoxicillin, is well distributed in body tissues.
Microbiology: Antimicrobial Actions: Co-amoxiclav is an antibacterial combination consisting of amoxicillin (as sodium) and the beta-lactamase inhibitor, clavulanic acid (as potassium clavulanate).
Amoxicillin is the 4-hydroxy analogue of ampicillin. Amoxicillin hinders the cell wall synthesis of sensitive bacteria and is bactericidal against many Gram-positive and Gram-negative bacteria. It is active against all penicillin-sensitive bacteria: Streptococci and most strains of pneumococci, gonococci and meningococci are sensitive. Bacteria that produce beta-lactamase (e.g. most of the staphylococci) are resistant. Amoxicillin is also active against strains of Haemophilus influenza that do not produce beta-lactamase. Amoxicillin is inactivated by β-lactamases and complete cross-resistance has been reported between amoxicillin and ampicillin. The spectrum of activity of amoxicillin may be extended by use with a β-lactamase inhibitor eg, clavulanic acid. As well as reversing resistance to amoxicillin in β-lactamase producing strains of species otherwise sensitive, clavulanic acid has also been reported to enhance the activity of amoxicillin against several species not generally considered sensitive. These have included: Bacteroides, Legionella and Nocardia spp, Haemophilus influenzae, Moraxella catarrhalis and Pseudomonas pseudomallei.
Clavulanic acid has a beta-lactam structure resembling that of penicillin nucleus, except that the fused thiazolidine ring of the penicillins is replaced by an oxazolidine ring. In general, clavulanic acid has only weak antibacterial activity. It is potent progressive inhibitor of plasmid-mediated and some chromosomal beta-lactamases produced by Gram-negative bacteria including Haemophilus ducreyi, H. influenzae, Neisseria gonorrhoeae, Moraxella catarrhalis (Branhamella catarrhalis), Bacteroides fragilis and some Enterobacteriaceae. It is also an inhibitor of the beta-lactamases produced by Staphylococcus aureus. Clavulanic acid can permeate bacterial cell walls and can therefore inactivate both extracellular enzymes and those that are bound to the cell. Its mode of action depends on the particular enzyme inhibited, but it generally acts as a competitive, and often irreversible, inhibitor. Clavulanic acid consequently enhances the activity of penicillin and cephalosporin antibacterials against many resistant strains of bacteria. However, it is generally less effective against chromosomally medicated type 1 beta-lactamases: therefore, many Citrobacter, Enterobacter, Morganella and Serratia spp. And Pseudomonas aeruginosa remain resistant. Some plasmid-mediated extended-spectrum beta lactamases in Klebsiella pneumoniae, some other Enterobacteriaceae, and Ps. aeruginosa are also not inhibited by beta-lactamases inhibitors.
Co-amoxiclav is bactericidal to a wide range of organisms including: Gram-Positive: Aerobes: Enterococcus faecalis, Enterococcus faecium, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus viridans, Staphylococcus aureus, Coagulase-negative staphylococci (including Staphylococcus epidermidis), Corynebacterium species, Bacillus anthracis, Listeria monocytogenes.
Anaerobes: Clostridium species, Peptococcus species, Peptostreptococcus.
Gram-Negative: Aerobes: Haemophilus influenzae, Moraxella catarrhalis (Branhamella catarrhalis), Escherichia coli, Proteus mirabilis, Proteus vulgaris, Klebsiella species, Salmonella species, Neisseria gonorrhoeae, Neisseria meningitidis, Vibrio cholerae, Pasteurella multocida.
Anaerobes: Bacteroides species, including B. fragilis.