Products
Azithromycin is commercially available in the form of film-coated tablets, powder for preparation of a suspension, and granules (Zithromax, generic). Furthermore, a granule for the preparation of a sustained-release oral suspension is available (Zithromax Uno). Eye drops have also been released in some countries. Azithromycin has been approved in many countries since 1992.
Structure and properties
Azithromycin (C38H72N2O12, Mr = 749.0 g/mol) is a structurally closely related derivative of erythromycin A and belongs to the azalide group. Unlike erythromycin, it has a 15-membered instead of a 14-membered heterocyclic ring. Azithromycin exists as a white powder that is practically insoluble in water. It is present in drugs as azithromycin monohydrate or azithromycin dihydrate.
Effects
Azithromycin (ATC J01FA10) has antibacterial properties. The effects are due to inhibition of bacterial protein synthesis by binding to the 50S subunit of ribosomes.
Indications
For the treatment of bacterial infectious diseases with susceptible pathogens. These include:
- Lower respiratory tract infections: bronchitis, pneumonia.
- Upper respiratory tract infections: Sinusitis, tonsillitis, pharyngitis, otitis media.
- Skin and wound infections
- Genital chlamydial infection
- Prevention of intracellular -complex infection in HIV-infected individuals.
Numerous other potential uses are described in the literature. In 2020, azithromycin was investigated in combination with the antimalarial drug hydroxychloroquine for the treatment of the new coronavirus disease Covid-19.
Dosage
According to the SmPC. The drugs can be taken independently of meals. Taking with food may improve gastrointestinal tolerance. An exception is the sustained-release suspension, which must be administered fasting. Generic tablets may be required to be taken fasting because there are no corresponding studies on absorption with food. Azithromycin has a long half-life of 2-4 days and therefore needs to be given only once daily. An advantage is the short duration of treatment, which is usually only 3 days. Azithromycin can also be given as a single dose in some cases.
Contraindications
- Hypersensitivity
For complete precautions, see the drug label.
Interactions
Unlike other macrolide antibiotics, azithromycin appears to have little interaction with CYP450 and does not inhibit the isoenzymes. Drug interactions have been observed with ciclosporin, rifabutin, ergotamine, vitamin K antagonists, and digoxin, among others. Antacids may decrease concentrations of azithromycin and should not be administered concomitantly.
Adverse Effects
The most common possible adverse effects include digestive symptoms such as loss of appetite, nausea, vomiting, diarrhea, abdominal pain, and constipation. Other possible side effects include allergic reactions, fatigue, headache, and candida mycosis. Serious side effects such as cardiovascular disorders, kidney and liver disease, pseudomembranous colitis, pancreatitis, severe skin reactions, and hearing impairment are rare. Azithromycin, like other macrolides, can prolong the QT interval and rarely, and especially in high-risk patients, cause life-threatening cardiac arrhythmias.
