Amoxicillin Guide, Meaning , Facts, Information and Description
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Amoxicillin | |
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(2S,5R,6R)-6-[(R)-2-amino-2-(4-hydroxyphenyl) acetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid | |
| Empirical formula | C16H19N3O5S |
| Molecular weight | 365.4 |
| Half life | 61.3 minutes |
| Excretion | renal |
| Pregnancy category | A (Australia) |
Amoxicillin (formerly amoxycillin in the British Pharmacopoeia) is a moderate-spectrum β-lactam antibiotic; used to treat bacterial infections caused by susceptible microorganisms. It is usually the drug of choice within the class because it is better absorbed, following oral administration, than other beta-lactam antibiotics. Amoxicillin is susceptible to degradation by β-lactamase;-producing bacteria, and so is often given clavulanic acid (see below). It is currently marketed by GlaxoSmithKline under the trade name Amoxil®.
Mode of action
Amoxicillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria.
Main article: beta-lactam antibiotic
Microbiology
Amoxicillin is a moderate-spectrum antibiotic active against a wide range of Gram-positive, and a limited range of Gram-negative organisms. Some examples of susceptible and resistant organisms, from the Amoxil® Approved Product Information (GSK, 2003), are listed below.
Susceptible Gram-positive organisms
Streptococcus spp., Diplococcus pneumoniae, non β-lactamase;-producing Staphylococcus spp., and Streptococcus faecalis.
All strains of Pseudomonas spp., Klebsiella spp., Enterobacter spp., indole-positive Proteus spp., Serratia marcescens, and Citrobacter spp. are resistant.
The incidence of β-lactamase-producing resistant organisms, including E. coli, appears to be increasing.
Main article: co-amoxiclavSusceptible Gram-negative organisms
Haemophilus influenzae, Neisseria gonorrhoeae, Neisseria meningitidis, Escherichia coli, Proteus mirabilis and Salmonella spp.Resistant organisms
Penicillinase producing organisms, particularly penicillinase producing Staphylococcus spp. Penicillinase-producing N. gonorrhoeae and H. influenzae are also resistantAmoxicillin and Clavulanic acid
Amoxicillin is sometimes combined with clavulanic acid, a β-lactamase inhibitor, to increase the spectrum of action against Gram-negative organisms, and to overcome bacterial antibiotic resistance mediated through β-lactamase production. This formulation is referred to as co-amoxiclav (British Approved Name), but more commonly by proprietary names such as Augmentin® and Clamoxyl®.