Azithromycin

Definition: Azithromycin is an antibiotic belonging to macrolide. It was discovered in 1980 and introduced in 1981. Also translated as a erythromycin, azithromycin. Azithromycin is a broad-spectrum antibiotic that has been modified on the structure of erythromycin and is suitable for respiratory tract infections, skin and soft tissue infections, and chlamydia-induced transmission diseases.

The pharmacological azithromycin is a 15-membered aza compound obtained by a series of reactions such as Becklman rearrangement and N-methylation after lipidation of erythromycin A9-keto, and it is also the first one in the group of azalids. Varieties, this structural difference hinders the formation of hemiketone acetal reaction, in which the hydrolysis of the ester bond to the neutral erythromycin is an important route of decomposition, the connection of erythromycin hydrolysis of the ester bond in azithromycin The activation energy is 15.6 kal. When mol-1 is used in 37°C and PH2 solutions (ionic strength = 0.02), it takes 21 min for azithromycin to degrade 10%. In the same case, erythromycin only takes 3.7 s. These results prove that azithromycin is comparable to erythromycin. The stability of the acid is greatly enhanced.

Azithromycin and erythromycin share common features in the antibacterial mechanism. They all bind to the 50S subunit of ribosomes in bacterial cells, hindering bacterial transpeptation and inhibiting the synthesis of RNA-dependent proteins to achieve antibacterial effects. However, due to structural changes, azithromycin has a broader spectrum of antibacterial activity than erythromycin and can inhibit a variety of Gram-positive cocci, mycoplasma, chlamydia, and Legionella pneumophila, especially for some important gram-negative bacilli such as influenza Blood bacillus has good antibacterial activity, which makes up for the lack of effect of macrolides on Haemophilus. Its effect on haemophilus influenzae is 4 to 8 times higher than that of erythromycin and roxithromycin, and it is 2 to 4 times that of erythromycin for influenza bacillus, moroccan catarrhalis, gonococcus, etc. It also has a certain antibacterial effect on E. coli. Azithromycin has the property of a dibasic parent, greatly enhancing the stability in acid and improving the bioavailability of oral administration. The transport of azithromycin in the body has its own unique features. Gedue et al. proposed the mechanism of phagocyte transmission of azithromycin, that is, azithromycin rapidly concentrates in polymorphonuclear leukocytes (PMN) and macrophages after administration, and transports it to the site of infection with the migration of phagocytic cells, giving rise to infection tissues. The very high concentration is maintained for a long period of time and then released as a response to the presence of pathogens at a concentration that exceeds the minimum inhibitory concentration (MIC) of many pathogens.

This transport mechanism determines its unique pharmacokinetic properties, with higher volumes of distribution, longer elimination half-lives, and broader cellular permeability than β-lactams, macrolides, and quinolones. The tissue concentration can be 300 times higher than the extracellular concentration, and elimination is slow. The tissue half-life is 68-76 h. Therefore, only once daily, once for 3 days, maintain an effective concentration of 8 to 10 days.

Domestic azithromycin is no different from imported products in terms of bioequivalence. The results showed that there was no significant difference in pharmacokinetic parameters between the two preparations (P < 0.05). The relative bioavailability of domestic azithromycin granules was 99.70%, and the two formulations were bioequivalent. However, for acute moderate-severe infection, the clinical role of azithromycin for injection is more accurate and rapid.

Adapt to symptoms 1, acute pharyngitis caused by Streptococcus pyogenes, acute tonsillitis.
2, sinusitis caused by sensitive bacteria, otitis media, acute bronchitis, acute exacerbation of chronic bronchitis.
3. Streptococcus pneumoniae, Haemophilus influenzae, and pneumonia caused by Mycoplasma pneumoniae.
4, Chlamydia trachomatis and non-multidrug resistant Neisseria gonorrhoeae caused by urethritis and cervicitis.
5. Skin and soft tissue infections caused by sensitive bacteria.

Azithromycin is mainly present in the form of capsules, granules and injections.

Azithromycin capsules Note 1, eating may affect the absorption of azithromycin, it is necessary to take oral 1 hour before meals or 2 hours after a meal.
2. Patients with mild renal insufficiency (creatinine clearance > 40 ml/min) do not need dose adjustment. However, azithromycin does not provide sufficient information for the use of patients with severe renal insufficiency. Care should be taken when using azithromycin in these patients.
3, because the liver and gallbladder system is the main route of azithromycin excretion, hepatic insufficiency with caution, severe liver disease patients should not be used. Routine follow-up of liver function during medication.
4. If an allergic reaction (such as angioneurotic edema, skin reactions, Stevens-Johnson syndrome, and toxic epidermal necrosis) occurs during drug use, discontinue the drug immediately and take appropriate measures. Some reactions due to azithromycin can be repeated and require a longer period of observation and treatment.
5. Like other antibiotics, attention should be paid to the observation of secondary infections caused by non-sensitive bacteria, including fungi.
6, during treatment, if the patient has diarrhea symptoms, should consider the occurrence of pseudomembranous colitis. If the diagnosis is established, appropriate treatment measures should be taken, including maintaining water, electrolyte balance, protein supplements, and so on.