What Is Azithromycin

When I had pneumonia, my doctor prescribed me to take Azitromycin. I always take antibiotics carefully. Before taking it, I have conducted my own research. I have found all the necessary information about its action and effects. Keep on reading to find out how this medicine works and what exactly it does.

Macrolides, along with beta-lactams and fluoroquinolones, still remain one of the most frequently prescribed antibiotics in outpatient practice. First of all, they are prescribed for the treatment of community-acquired bacterial respiratory infections, due to a number of their clinical and pharmacological features, first of all, activity against the majority of respiratory pathogens, including “atypical” pathogens, good tolerance and the presence of special non-antimicrobial properties that are characteristic only for drugs this class.

The first representative of macrolides is erythromycin, created back in 1952. The term “new macrolides” was used in the early 1990s. after the introduction into clinical practice of drugs such as azithromycin and clarithromycin. An important milestone in the history of this class of antibiotics was the appearance of Azithromycin in 1988, which is associated with a number of its unique pharmacokinetic and pharmacodynamic properties.

Clinical Pharmacology of Azithromycin

Azithromycin is a semisynthetic antibiotic, the first representative of the subclass of azalides, somewhat different in structure from the classical macrolides. Obtained by incorporating a nitrogen atom into a 14-membered lactone ring between 9 and 10 carbon atoms. The ring turns into a 15-atomic one, ceasing to be lactone. This restructuring causes a significant increase in the acid resistance of the drug – 300 times compared with erythromycin.

In addition to increased resistance to the action of hydrochloric acid, azithromycin, compared with erythromycin, has improved pharmacokinetic properties and a wider range of antimicrobial activity. In particular, azithromycin, to a greater extent than erythromycin, is able to penetrate the cell wall of gram-negative microorganisms and show more pronounced activity against H. influenzae, and also act on some members of the Eterobacteriaceae family.

The mechanism of action of azithromycin is similar to other macrolide antibiotics. The main point of the application is the 50S-subunit of the ribosome, interacting with which the macrolides violate protein synthesis mediated by mRNA. Macrolides have a bacteriostatic effect, but under certain conditions they can show a bactericidal effect on certain microorganisms. This property is most pronounced in azithromycin by creating higher intracellular concentrations.

Activity Spectrum and Resistance Problems

  • Gram positive cocci. Azithromycin is 2-4 times lower than erythromycin in vitro activity against staphylococci and streptococci, including S. pneumoniae, S. pyogenes and methicillin-sensitive strains of S. aureus. Streptococci and staphylococci resistant to erythromycin are resistant to azithromycin. Azithromycin, as well as erythromycin, has virtually no effect on most strains of enterococcus.
  • Gram-negative cocci. Azithromycin is significantly superior to erythromycin in the effects on N. gonorrhoeae and M. catarrhalis.
  • Gram-negative sticks. Azithromycin is the most active among macrolides against H. lnfluenzae, including beta-lactamase-producing strains. It is 2–8 times more effective than erythromycin in terms of effectiveness against this pathogen.

Compared with erythromycin, azithromycin has a slightly better effect on Legionella spp; H. ducreyi, Campylobacter spp., E. corrodens and P. multocida, and its activity against B. rertussis is the same as that of erythromycin. Azithromycin is superior to clarithromycin in activity against Bartonella spp., Which play an etiological role in cat scratch disease and bacillary angiomatosis.

A unique feature of azithromycin is that, unlike erythromycin and other macrolides, it is able to act in vitro on individual members of the Enterobacteriaceae family, such as E. coli, shigella and, to a lesser extent, salmonella. To azithromycin insensitive Pseudomonas spp. and Acinetobacter spp.

  • Chlamydia, mycoplasma. By activity against chlamydia, mycoplasmas and ureaplasmas, there is almost no difference between azithromycin and erythromycin.
  • Spirochetes. Azithromycin, to a greater extent than erythromycin, is active against B. burgdorferi, which cause Lyme disease. According to the effect on T. pallidum, both antibiotics are almost equivalent.
  • Rickettsia. Azithromycin is superior to clarithromycin in activity against C. burnetii – rickettsia causing atypical pneumonia.
  • Atypical mycobacteria. As well as clarithromycin, azithromycin acts on the intracellular complex of M. avium, which is naturally resistant to erythromycin.
  • The simplest. Unlike erythromycin, azithromycin is active against T. gondii, and also acts on cysts. In experimental studies revealed that azithromycin acts on Cryptosporidium spp.

Clinical Use of Azithromycin

Azithromycin is widely used in both adults and children. Most often it is used in infections of the upper and lower respiratory tract, urogenital infections, in patients with AIDS. Features of the pharmacokinetics of the drug can be applied once a day, which ensures high compliance of treatment. In case of respiratory and skin infections of the same degree, the therapeutic effect is achieved when an antibiotic is prescribed in either a five- or three-day course.

The ability of Azithromycin to create high and stable concentrations in the tissues and secretions of the reproductive organs, as well as its high activity against the main pathogens of urogenital infections, make it possible to prescribe the drug to patients with this pathology once. There are reports on the use of azithromycin in borreliosis and native infections. In AIDS patients, an antibiotic can be used to prevent disseminated opportunistic infections caused by the M. avium intracellular complex. There is information about the possibility of using azithromycin for the prevention of malaria.

The use of Azithromycin can significantly simplify the treatment of infections, improve compliance and, thereby, increase the effectiveness of antibiotic therapy.

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