Zithromax (Azithromycin) Antibiotic Tablets
Zithromax is a prescription oral macrolide antibiotic containing azithromycin. It is used in adults and children for respiratory tract infections, otitis media, sexually transmitted infections and skin and soft tissue infections, with convenient short-course regimens.
- Active ingredients
- Azithromycin
- Manufacturer
- Pfizer
- Dosage forms
- tablet, oral suspension, extended-release suspension
- Available dosages
- 250mg, 500mg, 600mg
- Category
- Antibiotics
What is it?
Zithromax is the original brand of azithromycin, marketed by Pfizer since the 1990s. It is supplied as oral tablets, oral suspension, extended-release suspension and parenteral solution. Multiple authorised generics of azithromycin are widely available, and the molecule is part of the World Health Organization List of Essential Medicines because of its broad clinical utility.
Active ingredients
Each tablet contains azithromycin (as the dihydrate) as the sole active ingredient at 250mg, 500mg or 600mg. Azithromycin is a semisynthetic 15-membered ring azalide antibiotic, structurally related to the 14-membered ring macrolide erythromycin.
Forms and dosages
Zithromax is administered orally once daily, often as a short course. According to the prescribing information, common adult regimens include 500mg on day 1 followed by 250mg daily on days 2-5, or a single 1g or 2g dose for some indications. Paediatric dosing is weight-based. The long tissue half-life supports short courses despite the rapid plasma half-life.
Indications
Zithromax is approved in adults and children for the treatment of community-acquired pneumonia, acute exacerbations of chronic bronchitis, sinusitis, pharyngitis caused by Streptococcus pyogenes, otitis media, urethritis and cervicitis caused by Chlamydia trachomatis or Neisseria gonorrhoeae, and skin and soft tissue infections. According to international guidelines, it is also used in the treatment and prophylaxis of Mycobacterium avium complex disease in immunocompromised patients.
How it works
Azithromycin binds to the 50S ribosomal subunit of bacteria, inhibiting protein synthesis. It is bacteriostatic against most susceptible organisms but bactericidal at high concentrations against some species. The molecule accumulates in tissues and inflammatory cells, producing high local concentrations that persist for days after a course is completed, supporting short dosing regimens.
Frequently asked questions
Why is Zithromax often prescribed as a short course? ▾
Azithromycin has a very long terminal half-life in tissues (around 68 hours), so therapeutic concentrations persist for days after the last dose. This supports short courses such as the 5-day or single-dose regimens described in the prescribing information, which improve adherence and reduce the total antibiotic exposure compared with conventional 7- to 10-day regimens for similar indications.
Does Zithromax interact with heart rhythm medications? ▾
Azithromycin can prolong the QT interval and has been associated with rare cases of torsades de pointes, particularly in patients with risk factors such as electrolyte disturbances or other QT-prolonging drugs. According to several regulatory communications, caution is advised in patients with cardiac arrhythmia, congenital long QT syndrome or those on other QT-prolonging medications. The prescriber should review the medication history.
Can I drink alcohol while taking Zithromax? ▾
Moderate alcohol intake does not directly interact with azithromycin in the same way as some antibiotics like metronidazole, but alcohol can worsen gastrointestinal side effects and slow recovery from the underlying infection. According to the prescribing information, patients with significant alcohol use should discuss this with the prescriber, and avoidance is generally recommended during acute infection.
Can children take Zithromax? ▾
Yes. Zithromax is approved in children, with weight-based dosing defined in the prescribing information. Oral suspension formulations facilitate paediatric administration. According to international guidelines, azithromycin is used in paediatrics for selected respiratory infections, particularly in patients with penicillin allergy, although first-line agents differ by indication.
What are the main contraindications for Zithromax? ▾
Zithromax is contraindicated in known hypersensitivity to azithromycin, erythromycin or other macrolides or ketolides, and in patients with a history of cholestatic jaundice or hepatic dysfunction associated with previous azithromycin use. Caution is required in QT prolongation, severe hepatic impairment and concurrent QT-prolonging drugs. According to the prescribing information, the medical history must be reviewed by a clinician before any prescription.
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