99% Purity Azithromycin CAS 83905-01-5 USP/Ep/Cep/FDA

1.Usage

Because the side effects of Azithromycin are less than Cephalosporins, now Azithromycin is the most commonly used antibiotics for bacterial infection-related diseases in our hospital clinic. This drug is a second generation semi-synthetic derivative of macrolide, whose structure is different from Erythromycin. It inserted a methyl-substituted nitrogen in 9a site of Erythromycin lactone ring, generating a 15-membered ring macrolide. 
The mechanism of action of Azithromycin is similar to Erythromycin. By binding to 50S subunit susceptible ribosome, Azithromycin inhibits protein synthesis which depends on RNA to show an antibacterial effect, retaining the antibacterial spectrum of typical Erythromycin. As for activity to chlamydia, Azithromycin is similar to Erythromycin. Compared with Erythromycin, antibacterial activity for gram-negative bacteria has been significantly improved, antibacterial activity for Haemophilus influenzae and Neisseria gonorrhoeae is more four times than Erythromycin, antimicrobial activity for Legionella bacteria is more about 2 times than Erythromycin, and antibacterial activity for Enterobacteriaceae is significantly stronger than Erythromycin. The MIC of most gram-negative bacteria is less than 1μg/ml. Staphylococcus aureus and Streptococcus pyogenes show cross-resistance on Azithromycin and Erythromycin. For toxoplasmosis and syphilis, Azithromycin also has a good role in the killing. Azithromycin is mainly used for respiratory tract infections, genitourinary tract infections, skin and soft tissue infections and sexually transmitted diseases which are caused by sensitive bacteria.

2.Pharmacokinetics

It is rapidly absorbed after oral administration, and its bioavailability is 37%. After a single oral dose of 0.5g, the peak time is 2.5 to 2.6 hours, peak plasma concentration (Cmax) is 0.4~0.45mg/L. This product is widely distributed in the body, and concentrations in each tissue are up to 10 to 100 times of the blood concentration over the same period. The plasma concentrations are high in macrophages and fibroblasts , the former can transport Azithromycin to inflammation sites. After a single dose administration of the product, elimination half-life of plasma concentration is 35 to 48 hours, more than 50% of the administered dose is excreted in the bile duct in original shape, and after 72 hours administration about 4.5% is excreted in the urine in original shape. With increasing plasma concentrations, serum protein binding rate of this product decreased. When the plasma concentration is 0.02 μg/mL, serum protein binding rate is 15%; when the blood concentration is 2 μg/mL, serum protein binding rate is 7%.

3.Antibacterial spectrum

1. Gram-positive aerobic bacteria, such as Staphylococcus aureus, Streptococcus pyogenes (A group β-hemolytic streptococcus), Streptococcus pneumoniae, α-hemolytic Streptococci (Streptococcus viridans group) and the other Streptococcus, Diphtheria (rodlike) bacteria. 
2. Gram-negative aerobic bacteria, such as Haemophilus influenzae, Haemophilus parainfluenza, catarrhal bacteria, Acinetobacter, Yersinia, Legionella spp, Bordetella pertussis, parapertussis, Shigella, Pasteurella spp., Vibrio cholerae, Vibrio parahaemolyticus, Shiga topiramate o Aeromonas. The activities for Escherichia coli, Salmonella enteritidis, Salmonella typhi, Enterobacter, addicted to waterborne Aeromonas and Klebsiella are not the same, and sensitivity test is needed.
3. Anaerobic bacteria, such as Bacteroides spp., Clostridium perfringens, Lactococcus digestion, digestion Streptococcus, Fusobacterium, Propionibacterium acnes.
4. Sexually transmitted disease microorganisms, such as Chlamydia trachomatis, Treponema pallidum, Neisseria gonorrhoeae, Haemophilus Duke.
5. Other microorganisms, such as Borrelia burgdorferi (Lyme pathogens), Chlamydia pneumoniae, Mycoplasma hominis, Ureaplasma urea, bending genus, mononucleosis and Lee de bacilli.
Azithromycin shows cross-resistance for Gram-positive bacteria with Erythromycin-resistant and various strains of Staphylococcus aureus with methicillin-resistant, and Gram-positive bacteria such as Proteus, Serratia, Morgan bacteria, Pseudomonas aeruginosa are usually resistant to Azithromycin.