Description
Azithromycin is an azalide macrolide antibiotic derived from erythromycin. Azithromycin binds the bacterial 50S ribosomal subunit, inhibiting protein translation. Azithromycin displays antibacterial, anti-fibrotic, and anti-inflammatory activities. In epithelial cells, azithromycin inhibits the epithelial-to-mesenchymal transition (EMT) by inhibiting expression of Smad3. Additionally, azithromycin inhibits production of arachidonic acid, eicosanoids, IL-6, and IL-12 in LPS-stimulated macrophages.
In vitro
Azithromycin displays a similar spectrum of antimicrobial activity. Azithromycin is marginally less active than erythromycin in vitro against Gram-positive organisms, although this is of doubtful clinical significance as susceptibility concentration fall within the range of achievable tissue Azithromycin concentrations. The mean MIC90 of Azithromycin against erythromycin susceptible/βL-ve strains, Streptococcus strains and NS (not selected for antimicrobial sesitivity)/erythromycin susceptible strains is 0.63, 0.35, and <0.27 mg/L, respectively. In contrast, Azithromycin appears to be more active than erythromycin against many Gram-negative pathogens and several other pathogens, notably Haemophilus influenza (MIC90, 1.34 mg/L), H. parainfluenzae(MIC90, 1 mg/L), Moraxella catarrhalis (MIC90, <0.1 mg/L), Neisseria gonorrhoeae (MIC90, 0.25 mg/L), Ureaplasma urealyticum, Bordetella spp (MIC90, 0.03-0.24 mg/L) and Borrelia burgdorferi. Azithromycin is also activity against clinical isolates of anaerobic bacteria Gram-positive cocci and propionibacterium acnes with MIC90 of 2.3, 0.03 mg/L. Like erythromycin and other macromycin, the activity of Azithromycin is unaffected by the production of β-lactamase. However, erythromycin-resistant organisms are also resistant to Azithromycin.
Uses
Azithromycin is a broad-spectrum macrolide antibiotic with a long half-life and a high degree of tissue penetration 3. It was initially approved by the FDA in 1991.
It is primarily used for the treatment of respiratory, enteric and genitourinary infections and may be used instead of other macrolides for some sexually transmitted and enteric infections. It is structurally related to erythromycin.
structure and hydrogen bonding
Azithromycin [9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin] is a part of the azalide subclass of macrolides, and contains a 15-membered ring, with a methyl-substituted nitrogen instead of a carbonyl group at the 9a position on the aglycone ring, which allows for the prevention of its metabolism. This differentiates azithromycin from other types of macrolides .
Mechanism of action
Azithromycin prevents bacteria from growing by interfering with their protein synthesis. It binds to the 50S subunit of the bacterial ribosome, thus inhibiting translation of mRNA. Nucleic acid synthesis is not affected.
Pharmacokinetics
Azithromycin is an acid-stable antibiotic, so it can be taken orally with no need of protection from gastric acids. It is readily absorbed, but absorption is greater on an empty stomach. Time to peak concentration (Tmax) in adults is 2.1 to 3.2 hours for oral dosage forms. Due to its high concentration in phagocytes, azithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations are released. The concentration of azithromycin in the tissues can be over 50 times higher than in plasma due to ion trapping and its high lipid solubility.[citation needed] Azithromycin's half-life allows a large single dose to be administered and yet maintain bacteriostatic levels in the infected tissue for several days. Following a single dose of 500 mg, the apparent terminal elimination half-life of azithromycin is 68 hours. Biliary excretion of azithromycin, predominantly unchanged, is a major route of elimination. Over the course of a week, about 6% of the administered dose appears as unchanged drug in urine.
Side Effects
Stomach upset, diarrhea/loose stools, nausea, vomiting, or abdominal pain may occur.
This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a resistant bacteria. This condition may occur during treatment or weeks to months after treatment has stopped.
Use of this medication for prolonged or repeated periods may result in oral thrush or a new yeast infection.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: fever that doesn't go away, new or worsening lymph node swelling, rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
Chemical Properties
White Solid
Uses
H1 antihistamine, nonsedating
Uses
Semi-synthetic macrolide antibiotic; related to Erythromycin A. Antibacterial.
Uses
Azithromycin dihydrate has anti-immunomodulatory/anti-inflammatory properties, which make it useful in treating cystic fibrosis. It shows an azalide antimicrobial agent active in vitro against various pathogens.
Definition
ChEBI: Azithromycin dihydrate is a hydrate. It contains an azithromycin.
brand name
Zithromax (Pfizer);
Zmax (Pfizer).
Biochem/physiol Actions
Azithromycin dihydrate is a macrolide antibiotic, azalide subclass. It binds to the 50S subunit of the 70S bacterial ribosomes and inhibits RNA-dependent protein synthesis in bacterial cells. Azithromycin also has anti-immunomodulatory/anti-inflammatory properties, which make it useful in treating cystic fibrosis.
