You are here
Home > Medicines > Amoxicillin


Amoxicillin is a penicillin antibiotic, belonging to the β-lactams, with the ability to interfere in the synthesis of the bacterial wall .

The ß-lactam antibiotics, such as amoxicillin, are widely used antibacterials since they have good pharmacokinetic characteristics in general, since some must be administered parenterally and have a relatively wide margin of safety.

How does this medicine work in the body?


Amoxicillin is an antibiotic capable of inhibiting the synthesis of the wall of bacteria. Due to this characteristic, microorganisms that lack a cell wall will be resistant to this antibiotic. Specifically, it is a bactericide, that is, a drug capable of killing the bacteria, which inhibits the action of two enzymes in particular:

  • Peptidase   or proteases: they are enzymes that break peptide bonds, which are the bonds by which proteins are bound using a water molecule.
  • Carboxypeptidases: are enzymes that belong to the group of the above and that are able to hydrolyze a peptide bond at the carboxy-terminal end of a protein or polypeptide, as a result, they release from that hydrolysis the amino acid located at the end of the chain. This will produce the death of the corresponding bacteria, since the cell wall is an essential structure for …?

It will produce the death of the corresponding bacteria, since the cell wall is an essential structure for your life

Against what bacteria does it act?

This antibacterial is a penicillin and these can be classified according to whether they are effective against Gram – or Gram + .

  • Reduced-spectrum penicillins active against Gram + , standard or classical penicillins:
    • Natural : are the benzylpenicillins, produced by the fungus Penicillium. The problem is that these are destroyed by the pH of the stomach, so they are administered parenterally, usually intramuscularly.
    • Acid-resistant: they are phenoxymethylpenicillin. These are resistant to gastric pH and are therefore administered orally.

From here, synthetic compounds were sought that on the one hand improved the spectrum of action and on the other improved the pharmacokinetic characteristics.

  • Resistant to β-lactamases of reduced spectrum towards Gram + : like cloxacillin.
  • Broad spectrum effective against Gram + and Gram – except pseudomonas :   whether or not they are effective against pseudomonas is used to indicate whether they are good drugs or very effective drugs against Gram – bacteria. It is the most important group and belongs to amoxicillin.
  • Broad spectrum active against pseudomonas.
  • Reduced spectrum active against Gram – especially against Enterobacteriaceae.

Indications of amoxicillin


Amoxicillin is indicated in the treatment of sitic or local infections due to Gram +, Gram – and some sensitive anaerobes in:

It is also indicated for:

Read also:


Amoxicillin can not be administered if the patient is or if the patient previously had a severe immediate allergic reaction to another ß-lactam. Neither should this medicine be administered in the case that the patient suffers from infectious mononucleosis, leukemia or sarcoma.

Adverse reactions of amoxicillin


Amoxicillin is a drug with a wide margin of safety , so it can be administered even to pregnant women. Although it crosses the placental barrier, the medication does not cause problems to the fetus and, in case of adverse effects, these will be of little relevance.

On the other hand, amoxicillin can produce the typical alterations in the . Therefore, whenever an antibacterial is taken, it is recommended to replace the intestinal flora. It is also possible that it produces allergic reactions.