Azithromycin is a 15-membered macrolide antibiotic that binds to the 50S subunit of bacterial ribosomes , inhibiting bacterial protein synthesis and exerting a bactericidal effect.
As a second-generation macrolide antibiotic , its antibacterial spectrum is similar to that of first-generation erythromycin, but it is significantly stronger than first-generation.
Azithromycin can inhibit bacterial growth at low concentrations and effectively kill bacteria at high concentrations. It has obvious antibacterial effects on Gram-positive cocci , Gram-negative cocci, some Gram-negative bacilli, such as Haemophilus influenzae , Bordetella pertussis, atypical pathogens, Legionella pneumophila , Mycoplasma pneumoniae, and Chlamydia.
Due to its good acid stability and obvious tissue permeability, azithromycin is widely use in clinical practice. Azithromycin can also be use as an alternative treatment for patients allergic to penicillin, cephalosporin, etc. It has a long half-life of up to 70 hours, so it only needs to be administer once a day.
Continuous administration for three days can maintain effective concentration for 8 to 10 days, with high bioavailability. In addition, the concentration in tissues and cells of infected sites is higher than that in blood.
Indications
Azithromycin is suitable for the following infections caused by sensitive bacteria: bronchitis, pneumonia, etc.; skin and soft tissue infections; acute otitis media ; sinusitis, pharyngitis, tonsillitis, etc. It can also be use for simple genital infections caused by Chlamydia trachomatis among sexually transmitted diseases in men and women .
Because it has an antibacterial effect on Chlamydia trachomatis, it can be use in combination with rifampicin for Chlamydia trachomatis infection. In addition, azithromycin has a certain effect on toxoplasmosis and can enter the cyst to kill toxoplasma, trophozoites and cysts.
Although azithromycin has the above advantages, its incompatibility and toxic side effects need to be taken seriously.
Adverse Reactions
1. The main symptoms are vomiting, abdominal distension, abdominal pain, diarrhea, and antibiotic-associated diarrhea.
2. Hepatotoxicity: It usually occurs about ten days after taking the drug, with common symptoms including hepatomegaly, abdominal pain, obstructive jaundice , increased AST and ACT, etc.
3. Cardiac toxicity: mainly arrhythmias, QT interval prolongation, torsade de pointes tachycardia, and in severe cases, syncope or sudden death may occur.
4. Ototoxicity: Especially in elderly patients with renal insufficiency , excessive dosage may cause deafness, tinnitus, etc., which usually occur within one to two weeks after taking the medicine.
Contraindications
1. It is contraindicate for patients who are allergic to macrolide enzymes.
2. Macrolide drugs are contraindicate or use with caution in some heart diseases (such as bradycardia , arrhythmia, ischemic heart disease, prolonged QT interval, and congestive heart failure ).
Current studies have shown that azithromycin can cause abnormal electrical activity of the heart, which can cause fatal arrhythmias and increase the risk of occurrence.
3. It is forbid to use in patients with liver dysfunction.
Drug interactions
1. When used in combination with chloramphenicol or lincomycin , it is not easy to use them together because of the antagonistic effect caused by competing for drug binding sites, which can easily cause bacteria to develop drug resistance and aggravate adverse reactions.
2. When used in combination with other hepatotoxic drugs, it will increase liver toxicity. For example , when use in combination with statins, the plasma concentration of statins will increase. Which may cause acute liver necrosis. If combined use is necessary, the dosage should be reduce or liver function should be check regularly.
3. Combination use with ototoxic drugs, such as aminoglycosides , may increase ototoxicity and should be avoid clinically.
4. When use in combination with theophylline drugs. The clearance rate of theophylline drugs can be reduce and the half-life can be prolonge. When use in combination, the dosage of theophylline drugs should be reduce or the blood concentration should be monitor.
Contraindications
According to the drug instructions and incompatibility table. Azithromycin cannot be use in combination with other intravenous infusions or additives, nor can it be drip into the same intravenous channel at the same time.
When used in combination with the proton pump inhibitor omeprazole , the liquid may turn yellow.
When used in combination with ambroxol , furosemide, cefpiramide, and ganciclovir injection , floccules and precipitation are likely to occur. When used in combination with rifampicin injection, tofu-like precipitation may occur.
In addition, azithromycin is relatively stable to acid, and antacids containing aluminum and magnesium. It can reduce the blood concentration of azithromycin. It can be take 1 hour before oral antacids or 2 hours after meals.
Long-term use with compound licorice tablets can easily cause arrhythmia. Whose main ingredients include licorice extract powder, opium powder , camphor, etc.
Modern pharmacological studies have show that glycyrrhizin is hydrolyz into glycyrrhetinic acid in the body. Which has a mineralocorticoid- like effect, and can cause hypokalemia by acting on the renal tubules. Taking azithromycin at the same time can more easily induce malignant arrhythmias .
Clinical application
With the widespread clinical application, bacterial resistance to macrolides has also increased significantly. Some bacteria produce inactivating enzymes that destroy the chemical structure of macrolide antibiotics, which also leads to bacterial resistance.
Therefore, drug indications, interactions, and contraindications related to drug combinations need to be consider during clinical medication.
In addition, in order to reduce gastrointestinal discomfort, there have been reports that 654-2 injection or vitamin B6 injection was mix with azithromycin for drip infusion. Although no incompatibility was found, in order to avoid medical disputes, it is better to be cautious and use the drugs alone and try not to mix them.
Finally, let me share my experience in using azithromycin. When encountering patients with irritating dry cough in clinical practice, especially those with a course of illness of more than one week. The use of penicillin or cephalosporin antibiotics has no obvious effect, and there are no testing conditions. It is necessary to consider the possibility of mycoplasma infection and replace it with azithromycin. Which often has a significant effect.
At the same time, this drug should not be use for patients with concurrent gastrointestinal bleeding, gastrointestinal ulcers, pyloric obstruction , abdominal pain, arrhythmia, abnormal liver function, etc., so as not to mask the condition or aggravate the original disease.
