Important points about the use of azithromycin.📜📜📜

Azithromycin is a macrolide antibiotic. The structure of these antibiotics has a giant ring lactone and has one or more deoxysugar linkages. They can be used as replacement drugs in patients allergic to β-lactam antibiotics. Azithromycin has many clinical advantages. There is no need for a skin test before using it. It has a broad antibacterial spectrum. Under normal circumstances, patients only need to take it once a day, which can improve patient compliance. Therefore, it is a very commonly used oral antibiotic. The following will explain how to properly use azithromycin.

Pharmacological effects.

Azithromycin irreversibly binds to the 23SrRNA of the 50S ribosomal subunit of susceptible bacteria, thereby inhibiting the transfer step of bacterial protein synthesis and preventing the assembly of the 50S ribosomal subunit. 

Dosage form and usage.

Azithromycin is clinically available in different dosage forms, but their potency is not necessarily the same. They need to pass the consistency evaluation to be considered equal.

• Tablets ≠ dispersible tablets ≠ enteric-coated tablets. Capsule ≠ soft capsule ≠ enteric-coated capsule.

Different dosage forms are used differently. 

For azithromycin tablets, take orally once daily and swallow the tablet whole. It can be taken with or without food.

For azithromycin capsules, take orally once daily and swallow the tablet whole. It should be taken at least one hour before meal or at least two hours after meal. 

Azithromycin dispersible tablets, enteric-coated tablets or soft capsules are generally taken at least one hour before meal or at least two hours after meal. The actual situation is based on the drug instruction.

The half-life of azithromycin is 68 hours, which is relatively long. Patients stop taking it after 3 days and it will still work in the body for 3 to 4 days. Therefore, mild and moderate infection patients take 500mg once a day for three days, with a total dose of 1500mg. 

Is azithromycin preferred for mycoplasma pneumonia?

In the past, azithromycin was the first choice for mycoplasma pneumonia. However, with the increasing rates of resistance to erythromycin and azithromycin in mycoplasma isolated from adult patients with community-acquired pneumonia. Although these mycoplasmas have increased resistance to macrolides, they remain susceptible to quinolones, doxycycline, or minocycline. When a patient is suspected of having mycoplasma pneumonia, antibiotics are selected according to his age: 

• When the patient is less than 8 years old, azithromycin is the first choice for him.
• When the patient is 8 years or older, azithromycin is preferred for him. Alternatively, doxycycline or minocycline may be used on him.
• When the patient is 18 years or older, doxycycline and minocycline are preferred. In addition, quinolone antibiotics such as moxifloxacin can also be considered for him.

Off-label medication.

In addition to its broad antibacterial effects, azithromycin has many other effects including disruption of biofilms, changes in macrophage phenotype, modulation of the immune system, and regulation of airway surface liquid electrolytes and mucus. Therefore, azithromycin will be used off-label.

1. Prevention and treatment of bronchial asthma: Asthma patients have persistent symptoms despite the use of combined treatment with moderate or high doses of inhaled corticosteroids and long-acting β₂ agonists. Addition of azithromycin can reduce acute asthma attack and improve quality of life in patients. Patients received oral azithromycin 250 to 500 mg three times a week for 26 to 48 weeks.
2. Treatment of adult bronchiectasis: For patients with acute exacerbations of bronchiectasis greater than or equal to 3 times per year, it is recommended that patients receive oral low-dose azithromycin for at least 3 months. The initial therapeutic dose is 250 mg orally, 3 times a week to once a day. Adjust the dose or discontinue the drug according to clinical efficacy and adverse reactions.
3. Treatment of chronic obstructive pulmonary disease: Consider adding azithromycin to patients who still experience acute exacerbations on combination therapy with inhaled corticosteroids, long-acting β₂ agonists and long-acting muscarinic antagonists, especially those with a history of smoking. Studies have shown that cigarette-induced lung inflammation and emphysema in mice can be alleviated by low-dose azithromycin.

Precautions for medication.

The capsule form of azithromycin should not be taken with food.

Azithromycin promotes gastrointestinal motility and may cause dysbiosis in the gastrointestinal tract. Therefore, patients who develop bloody or watery stools during medication or for 2 months or longer after medication should go to see a doctor as soon as possible.

Azithromycin prolongs the QT interval. Patients should go to see a doctor as soon as possible if they experience cardiac discomfort during or after taking azithromycin.

Azithromycin is hepatotoxic and ototoxic. If the patient develops related symptoms, the drug should be discontinued immediately.