Ziomycin

Ziomycin Mechanism of Action

azithromycin

Manufacturer:

Kusum

Distributor:

JDS
Full Prescribing Info
Action
Pharmacotherapeutic group: Antibacterial for systemic use. ATC code: J01FA10.
Pharmacology: Pharmacodynamics: ZIOMYCIN contains azithromycin which is a macrolide antibiotic belonging to the azalide group. The molecule is constructed by adding a nitrogen atom to the lactone ring of erythromycin A. The chemical name of azithromycin is 9deoxy9αaza9α methyl9α homoerythromycin A. The molecular weight is 749.0. The mechanism of action of azithromycin is based upon the suppression of bacterial protein synthesis by means of binding to the ribosomal 50s subunit and inhibition of peptide translocation.
Pharmacokinetics: Absorption: Bioavailability after oral administration is approximately 37%. Peak plasma concentrations are attained 23 hours after taking the medicinal product.
Distribution: Orally administered azithromycin is widely distributed throughout the body. In pharmacokinetic studies it has been demonstrated that the concentrations of azithromycin measured in tissues are noticeably higher (as much as 50 times) than those measured in plasma, which indicates that the agent strongly binds to tissues.
Binding to serum proteins varies according to plasma concentration and ranges from 12% at 0.5 microgram/ml up to 52% at 0.05 microgram azithromycin/ml serum. The mean volume of distribution at steady state (VVss) has been calculated to be 31.1 l/kg.
Elimination: The terminal plasma elimination halflife closely reflects the elimination halflife from tissues of 24 days.
Approximately 12% of an intravenously administered dose of azithromycin is excreted unchanged in urine within the following three days. Particularly high concentrations of unchanged azithromycin have been found in human bile. Also in bile, ten metabolites were detected, which were formed through N- and O-demethylation, hydroxylation of desosamine - and aglycone rings and cleavage of cladinose conjugate. Comparison of the results of liquid chromatography and microbiological analyses has shown that the metabolites of azithromycin are not microbiologically active.
In animal tests, high concentrations of azithromycin have been found in phagocytes. It has also been established that during active phagocytosis higher concentrations of azithromycin are released from inactive phagocytes. In animal models this results in high concentrations of azithromycin being delivered to the site of infection.
Microbiology: Mechanism of resistance: Resistance to azithromycin may be inherent or acquired. There are three main mechanisms of resistance in bacteria: target site alteration, alteration in antibiotic transport and modification of the antibiotic.
Azithromycin demonstrates cross resistance with erythromycin resistant gram positive isolates. A decrease in macrolide susceptibility over time has been noted particularly in Streptococcus pneumoniae and Staphylococcus aureus. Similarly, decreased susceptibility has been observed among Streptococcus viridans and Streptococcus agalactiae (Group B) streptococcus against other macrolides and lincosamides.
Breakpoints: Azithromycin susceptibility breakpoints for typical bacterial pathogens, as published by EUCAST are: See table.

Click on icon to see table/diagram/image

Susceptibility: The prevalence of acquired resistance may vary geographically and with time for selected species and local information on resistance is desirable, particularly when treating severe infections. As necessary, expert advice should be sought when local prevalence of resistance is such that the utility of the agent in at least some types of infections is questionable.
Antibacterial spectrum of Azithromycin: Commonly susceptible species: Aerobic Gram-positive microorganisms: Staphylococcus aureus, Methicillin-susceptible, Streptococcus pneumoniae, Penicillin-susceptible, Streptococcus pyogenes (Group A).
Aerobic Gram-negative microorganisms: Haemophilus influenzae, Haemophilus parainfluenzae, Legionella pneumophila, Moraxella catarrhalis, Neisseria gonorrhoeae, Pasteurella multocida.
Anaerobic microorganisms: Clostridium perfringens, Fusobacterium spp., Prevotella spp., Porphyromonas spp.
Other microorganisms: Chlamydia trachomatis.
Species for which acquired resistance may be a problem: Aerobic Gram-positive microorganisms: Streptococcus pneumoniae, Penicillin-intermediate, Penicillin-resistant.
Inherently resistant organisms: Aerobic Gram-positive microorganisms: Enterococcus faecalis, Staphylococci MRSA, MRSE*.
Anaerobic microorganisms: Bacteroides fragilis group.
*Methicillin-resistant staphylococci have a very high prevalence of acquired resistance to macrolides and have been placed here because they are rarely susceptible to azithromycin.
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