Азитромицин

Описание

Azithromycin was the first of the azalides and was designed to improve the stability and biological half-life of erythromycin A, as well as improve activity against Gram negative bacteria. Azithromycin is a long-acting macrolide antibiotic structurally related to erythromycin A (EA), having a methyl-substituted nitrogen at position 9a in the aglycone ring.

Химические свойства

White Crystalline Powder

Определение

ChEBI: Azithromycin is a macrolide antibiotic useful for the treatment of bacterial infections. It is an azalide, derived from erythromycin, and a member of a subclass of macrolide antibiotics with bacteriocidal and bacteriostatic activities.

Показания

Azithromycin in a 500-mg dose three times a week has been shown to yield a 60% reduction in inflammatory papules in 83% of patients enrolled in a 12- week study. There is no associated pseudotumor cerebri and, therefore, it can be used for an acne flare during early Accutane therapy.

Антимикробная активность

It is less potent than erythromycin A against Gram-positive isolates, but is more active against Gram-negative bacteria. It is four times more potent than erythromycin A against H. influenzae, N. gonorrhoeae and Campylobacter spp., and twice as active against Mor. catarrhalis. It also exhibits superior potency against Enterobacteriaceae, notably Esch. coli, Salmonella enterica serotypes, and Shigella spp. It is active against Mycobacteria, notably the M. avium complex and against intracellular micro-organisms such as Legionella and Chlamydia spp.
Chemical modification at the 9 position of the erythronolide A ring of erythromycin A blocks the internal ketalization and markedly improves acid stability. At pH 2, loss of 10% activity occurred in less than 4 s with erythromycin A, but took 20 min with azithromycin. The AUC at 0–24 h is 4.5 mg.h/L. The level is only slightly increased on repeated dosing.
Binding to plasma protein varies with the concentration, from around 50% at 0.05 mg/L to 7.1% at 1 mg/L. The apparent elimination half-life is dependent upon sampling interval: between 8 and 24 h it ranged from 11 to 14 h; between 24 and 72 h it was 35–40 h.
It rapidly penetrates the tissues, reaching levels that approach or, in some cases, exceed the simultaneous plasma levels and persist for 2–3 days. Only about 6% of the dose is found in urine in the first 24 h.

Общее описание

The spectrum of antimicrobial activity of azithromycin issimilar to that observed for erythromycin and clarithromycinbut with some interesting differences. In general,it is more active against Gram-negative bacteria and less activeagainst Gram-positive bacteria than its close relatives.The greater activity of azithromycin against H. influenzae,M. catarrhalis, and M. pneumoniae coupled with its extendedhalf-life permits a 5-day dosing schedule for thetreatment of respiratory tract infections caused by thesepathogens. The clinical efficacy of azithromycin in the treatmentof urogenital and other sexually transmitted infectionscaused by Chlamydia trachomatis, N. gonorrhoeae, H.ducreyi, and Ureaplasma urealyticum suggests that singledosetherapy with it for uncomplicated urethritis or cervicitismay have advantages over use of other antibiotics.

Биологическая активность

Azithromycin is a macrolide antibiotic. It is active against S. pneumoniae, S. aureus, N. gonorrhoeae, M. pneumoniae, H. pylori, C. trachomatis, and H. influenzae in vitro (MIC90s = <0.01-2 mg/L). Azithromycin increases survival in mouse models of intraperitoneal S. pyogenes, S. pneumoniae, E. faecalis, or H. influenzae infection (ED50s = 0.78, 8.7, 12.7, and 30.3 mg/kg, respectively). It inhibits replication of severe acute respiratory coronavirus 2 (SARS-CoV-2), but not Middle East respiratory syndrome CoV (MERS-CoV), when used at concentrations of 5 and 10 μM. Azithromycin also decreases plasma levels of IL-6, TNF-α, and IL-1β and increases survival in a mouse model of LPS-induced sepsis when administered at a dose of 100 mg/kg. Formulations containing azithromycin have been used in the treatment of a variety of bacterial infections.

Фармакокине?тика

Oral absorption：37%
Cmax 250 mg oral： 0.17 mg/L after 2.2 h
500 mg oral： 0.4 mg/L after2h
Plasma half-life (terminal)： 11–40 h
Volume of distribution： 31 L/kg
Plasma protein binding ：7–50%
Chemical modification at the 9 position of the erythronolide A ring of erythromycin A blocks the internal ketalization and markedly improves acid stability. At pH 2, loss of 10% activity occurred in less than 4 s with erythromycin A, but took 20 min with azithromycin. The AUC at 0–24 h is 4.5 mg.h/L. The level is only slightly increased on repeated dosing.
Binding to plasma protein varies with the concentration, from around 50% at 0.05 mg/L to 7.1% at 1 mg/L. The apparent elimination half-life is dependent upon sampling interval: between 8 and 24 h it ranged from 11 to 14 h： between 24 and 72 h it was 35–40 h.
It rapidly penetrates the tissues, reaching levels that approach or, in some cases, exceed the simultaneous plasma levels and persist for 2–3 days. Only about 6% of the dose is found in urine in the first 24 h.

Клиническое использование

This product is suitable for the treatment of the following symptoms of infection caused by susceptible bacteria:
1. For acute pharyngitis and acute tonsillitis caused by Streptococcus pyogenes and for nasosinusitis, acute otitis media, acute bronchitis, and acute exacerbation of chronic bronchitis caused by sensitive bacteria.
2. For pneumonia caused by Mycoplasma pneumonia, Streptococcus pneumonia and Haemophilus influenza.
3. For urethritis, cervicitis and pelvic inflammatory disease caused by chlamydia and non-multiple drug resistance Neisseria gonorrhoeae, and for simple genital infection caused by non-multiple drug resistance Neisseria gonorrhoeae (exclude co-infection of Misu spirochetes).
4. For skin and soft tissue infections caused by sensitive bacteria.

Побочные эффекты

Azithromycin is well tolerated with little gastrointestinal disturbance.

Способ действия

Azithromycin reversibly binds to the 50S ribosomal subunit of the 70S ribosome of sensitive microorganisms, thereby inhibiting the translocation step of protein synthesis, wherein a newly synthesized peptidyl tRNA molecule moves from the acceptor site on the ribosome to the peptidyl (donor) site, and consequently inhibiting RNA-dependent protein synthesis leading to cell growth inhibition and cell death.