Aminoside

The aminosides ( aminoglycosides ) constitute a Famille of antibiotic S credits on certain types of Bactérie S. They include/understand the Amikacine, the Gentamicine, the Kanamycine, the Néomycine, the Nétilmicine, the Paromomycine, the Streptomycine (more known, discovered by Selman Abraham Waksman), and the Tobramycine. Those which are derived from species of Streptomyces take the suffix - mycine , those which are derived from Micromonospora take the suffix - micine .

Chemical structure

The aminoglycosides are composed of two to five units of sugars subsitués by functions amine (- NH₂). The majority of them are built around a common central core, made up of 2-désoxystreptamine and glucosamine (see figure). This minimal structure corresponds to the antibiotic néamine or néomycine A. the majority of the aminosides used in private clinic comprise the other amino sugars, substituted either in position 4, or in position 5 of the cycle désoxystreptamine. There are thus two families of aminosides:

aminosides 4,6 disubstituted, such as the kanamycine, gentamicin or the amikacine
aminosides 5,6 disubstituted, such as the néomycine or the ribostamycine.

Mechanism of action

Aminosides bind to the sub-unit 30S Ribosome S of the bacteria and interfere with the translation of ARN messenger S out of proteins. More precisely, the majority of the aminoglycosides set at ribosomal ARN 16S, on the level of the site of decoding (site A). This fixing does not block the translation, but induced errors in the decoding of the Codon S carried out by ribosome. It is the accumulation of the errors in the proteins synthesized which is responsible for the lethality induced by the aminosides, by the accumulation of aberrant proteins.

Post-antibiotic effect

The post-antibiotic effect is a very particular phenomenon, only observed with the most powerful antibiotics. This effect occurs with the aminosides: even after the major part of the amount was eliminated from the organization, and that it remains only of weak traces of aminoside in the body, the weak remaining concentration of antibiotic continuous to act and to eliminate the bacteria. The aminosides thus have a stronger effect and wider than could not let it suppose their half-life alone.

Side effects

The aminoglycosides are toxic at the cells Eucaryote S. the principal mechanism of this toxicity is the blocking of ribosomes mitochondriaux which are also sensitive to the action of these compounds. The low permeability mitochondriale limit this effect. At the man, there exists however a toxicity proven on the level of the ears (Ototoxique S) and Rein S which requires a monitoring at the time of the administration by general way. The renal attacks are a consequence of the concentration of the aminosides on the level of this body.

Ototoxicity can be of two types, either reversible (attack of balance), or irreversible (deafness). It is amount-dependant, but at certain predisposed subjects, it can occur as of the first amount. The latter often have a change on DNA mitochondrial, and thus, only transmissible by the mother.

Precautions for use

One manages them with amounts based on the body weight. It is necessary to supervise the plasmatic Taux, the renal function (Créatinine) and it can be relevant to pass from the Audiogramme S of control after the treatment.

The aminosides should not be managed during the pregnancy (with less of extreme need), considering the big risk to make the newborn deaf.

Route of administration

There does not exist the oral shape of these antibiotics because they do not pass the digestive barrier. They thus in general either are managed by intravenous way, or used by local way for the treatment of the wounds.

Antibiotic spectrum

The aminosides are active against certain bacilli with negative Gram, in particular the Entérobactérie S and Pseudomonas aeruginosa. The streptomycine is useful to treat the Tuberculose resistant to the usual treatments, spectinomycin comes to end from the resistant Gonorrhée, and the paromomycine is a pesticide employed against some Amibe S and the Cryptosporidium.

Like the antibiotic majority, they are without effects on mushrooms and the viruses.

The aminosides are without effect against the anaerobic bacteria.

External bond

MedlinePlus information drugs

References

Random links: