Overview

Azithromycin is a broad-spectrum macrolide antibiotic with a long half-life and a high degree of tissue penetration . It was initially approved by the FDA in 1991 . It is primarily used for the treatment of respiratory, enteric and genitourinary infections and may be used instead of other macrolides for some sexually transmitted and enteric infections. It is structurally related to erythromycin . Azithromycin [9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin] is a part of the azalide subclass of macrolides, and contains a 15-membered ring, with a methyl-substituted nitrogen instead of a carbonyl group at the 9a position on the aglycone ring, which allows for the prevention of its metabolism. This differentiates azithromycin from other types of macrolides . In March 2020, a small study was funded by the French government to investigate the treatment of COVID-19 with a combination of azithromycin and the anti-malaria drug hydroxychloroquine. The results were positive, all patients taking the combination were virologically cured within 6 days of treatment, however, larger studies are required.

Indication

Azithromycin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria in order to prevent the development antimicrobial resistance and maintain the efficacy of azithromycin . Azithromycin is indicated for the treatment of patients with mild to moderate infections caused by susceptible strains of the microorganisms listed in the specific conditions below. Recommended dosages, duration of therapy and considerations for various patient populations may vary among these infections. Refer to the FDA label and "Indications" section of this drug entry for detailed information . Adults: Acute bacterial exacerbations of chronic obstructive pulmonary disease due to Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae Acute bacterial sinusitis due to Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae Community-acquired pneumonia due to Chlamydophila pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae or Streptococcus pneumoniae in patients appropriate for oral therapy Pharyngitis/tonsillitis caused by Streptococcus pyogenes as an alternative to first-line therapy in individuals who cannot use first-line therapy. Uncomplicated skin and skin structure infections due to Staphylococcus aureus, Streptococcus pyogenes, or Streptococcus agalactiae. Abscesses usually require surgical drainage. Urethritis and cervicitis due to Chlamydia trachomatis or Neisseria gonorrhoeae. Genital ulcer disease in men due to Haemophilus ducreyi (chancroid). Due to the small number of women included in clinical trials, the efficacy of azithromycin in the treatment of chancroid in women has not been established. Pediatric Patients Acute otitis media caused by Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae Community-acquired pneumonia due to Chlamydophila pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae or Streptococcus pneumoniae in patients appropriate for oral therapy. Pharyngitis/tonsillitis caused by Streptococcus pyogenes as an alternative to first-line therapy in individuals who cannot use first-line therapy.

Associated Conditions

Acute Bacterial Sinusitis (ABS)
Acute Otitis Media (AOM)
Acute bacterial exacerbation of COPD caused by Haemophilus Influenza Infections, Moraxella Catarrhalis Infection, Streptococcus Pneumoniae Infections
Bacterial Conjunctivitis
Bacterial Sinusitis
Cervicitis
Chancroid
Community Acquired Pneumonia (CAP)
Genital Ulcer Disease (GUD)
Pelvic Inflammatory Disease (PID)
Pharyngitis
Streptococcal Pharyngitis
Tonsillitis bacterial
Tonsillitis streptococcal
Traveler's Diarrhea
Uncomplicated Skin and Skin Structure Infections
Urethritis

Research Report

Published: Jul 14, 2025

Azithromycin (DB00207): A Comprehensive Monograph on its Pharmacology, Clinical Utility, and Safety Profile

Executive Summary

Azithromycin is a semi-synthetic, second-generation macrolide antibiotic belonging to the azalide subclass, distinguished by a 15-membered macrocyclic lactone ring. Since its discovery in 1980 and subsequent US FDA approval in 1991, it has become one of the most widely prescribed antibiotics globally, valued for its broad spectrum of activity, unique pharmacokinetic profile, and convenient dosing regimens.[1] Its mechanism of action involves the inhibition of bacterial protein synthesis via binding to the 50S ribosomal subunit, effectively halting bacterial growth.[1] Beyond this primary antibacterial effect, azithromycin exhibits significant immunomodulatory and anti-inflammatory properties, which contribute to its efficacy in chronic inflammatory airway diseases.[2]

The drug's defining characteristic is its pharmacokinetic profile, marked by rapid absorption, extensive tissue distribution, and profound intracellular accumulation, particularly within phagocytic cells. This "ion-trapping" phenomenon, coupled with a long terminal elimination half-life of approximately 68 hours, allows for short-course therapeutic regimens (e.g., 3-5 days) that maintain effective drug concentrations at the site of infection for a prolonged period.[5] This profile, combined with minimal interaction with the cytochrome P450 system, distinguishes it from older macrolides like erythromycin.[7]

Continue reading the full research report

Clinical Trials

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Title	Posted	Study ID	Phase	Status	Sponsor
Eosinophil-guided Reduction of Inhaled Corticosteroids	2020/07/22	NCT04481555	Phase 4	Recruiting	Chronic Obstructive Pulmonary Disease Trial Network, Denmark
Administration of Allogenic UC-MSCs as Adjuvant Therapy for Critically-Ill COVID-19 Patients	2020/07/07	NCT04457609	Phase 1	UNKNOWN	Indonesia University
A Study of Combination Therapies to Treat COVID-19 Infection	2020/07/07	NCT04459702	Phase 2	Withdrawn	ProgenaBiome
Non-comparative Trial of the Combination of HCQ and AZI in the Treatment of ICU Patients	2020/07/07	NCT04458948	Phase 2	Terminated	University of New Mexico
Azithromycin Treatment for Readthrough of APC Gene Stop Codon Mutations in Familial Adenomatous Polyposis	2020/07/01	NCT04454151	Phase 4	UNKNOWN	Tel-Aviv Sourasky Medical Center
Convalescent Plasma Therapy on Critically-ill Novel Coronavirus (COVID-19) Patients	2020/06/22	NCT04441424	Not Applicable	Completed	Alkarkh Health Directorate-Baghdad
Effects of Mass Drug Administration of Azithromycin on Mortality and Other Outcomes Among 1-11 Month Old Infants in Mali	2020/06/11	NCT04424511	Phase 3	Completed	Tampere University
Hydroxychloroquine, Azithromycin in the Treatment of Covid-19	2020/05/28	NCT04405921	Phase 3	UNKNOWN	Centre Hôpital Universitaire Farhat Hached
Ivermectin-Azithromycin-Cholecalciferol (IvAzCol) Combination Therapy for COVID-19	2020/05/22	NCT04399746	Not Applicable	Completed	Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado
International ALLIANCE Study of Therapies to Prevent Progression of COVID-19	2020/05/20	NCT04395768	Phase 2	UNKNOWN	National Institute of Integrative Medicine, Australia

FDA Drug Approvals

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Approved Product	Manufacturer	NDC Code	Route	Strength	Effective Date
Zithromax	Pfizer Laboratories Div Pfizer Inc	0069-0400	INTRAVENOUS	500 mg in 5 mL	1/27/2022
Azithromycin	Bryant Ranch Prepack	63629-7784	ORAL	500 mg in 1 1	12/8/2021
Azithromycin	Teva Pharmaceuticals USA, Inc.	0093-2027	ORAL	100 mg in 5 mL	7/26/2022
Azithromycin	STATE HEALTH SERVICES, TEXAS DEPARTMENT OF	55695-003	ORAL	200 mg in 5 mL	2/29/2024
Azithromycin	A-S Medication Solutions	50090-3213	ORAL	250 mg in 1 1	4/17/2017
Azithromycin	Aidarex Pharmaceuticals LLC	33261-139	ORAL	250 mg in 1 1	8/14/2018
Azithromycin	NuCare Pharmaceuticals,Inc.	68071-4976	ORAL	500 mg in 1 1	2/19/2021
Azithromycin Dihydrate	PD-Rx Pharmaceuticals, Inc.	72789-081	ORAL	250 mg in 1 1	3/31/2023
Azithromycin	Vivimed Labs Limited	62980-962	ORAL	600 mg in 1 1	9/23/2017
AZITHROMYCIN	WOCKHARDT LIMITED	55648-964	ORAL	500 mg in 1 1	12/16/2009

EMA Drug Approvals

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UK EMC Drug Information

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