Azithromycin (EENT) (Monograph)

Brand name: AzaSite
Drug class: Antibacterials

Medically reviewed by Drugs.com on Nov 10, 2024. Written by ASHP.

Introduction

Azithromycin is a macrolide antibiotic.

Uses for Azithromycin (EENT)

Azithromycin has the following uses:

Azithromycin 1% ophthalmic solution is used for the topical treatment of bacterial conjunctivitis caused by susceptible isolates of the following microorganisms: CDC coryneform group G, Haemophilus influenzae, Staphylococcus aureus, Streptococcus mitis group, and Streptococcus pneumoniae.

Azithromycin (EENT) Dosage and Administration

General

Azithromycin is available in the following dosage form(s) and strength(s):

2.5 mL of 1% sterile topical ophthalmic solution.

Dosage

It is essential that the manufacturer's labeling be consulted for more detailed information on dosage and administration of this drug. Dosage summary:

Dosage in Adults and Pediatric Patients

Instill 1 drop in the affected eye(s) twice daily, 8 to 12 hours apart for the first two days and then instill 1 drop in the affected eye(s) once daily for the next 5 days.

Cautions for Azithromycin (EENT)

Contraindications

Hypersensitivity to any component of the product.

Warnings/Precautions

Topical Ophthalmic Use Only

NOT FOR INJECTION. Azithromycin 1% topical ophthalmic solution is indicated for topical ophthalmic use only, and should not be administered systemically, injected subconjunctivally, or introduced directly into the anterior chamber of the eye.

Anaphylaxis and Hypersensitivity with Systemic Use of Azithromycin

In patients receiving systemically administered azithromycin, serious allergic reactions, including angioedema, anaphylaxis, and dermatologic reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis have been reported rarely in patients on azithromycin therapy. Although rare, fatalities have been reported. The potential for anaphylaxis or other hypersensitivity reactions should be considered based on known hypersensitivity to azithromycin when administered systemically.

Growth of Resistant Organisms with Prolonged Use

As with other anti-infectives, prolonged use may result in overgrowth of non-susceptible organisms, including fungi. If super-infection occurs, discontinue use and institute alternative therapy. Whenever clinical judgment dictates, the patient should be examined with the aid of magnification, such as slit-lamp biomicroscopy, and where appropriate, fluorescein staining.

Contamination of the Applicator Tip

Avoid contaminating the applicator tip by not allowing it to touch the eye, fingers or other sources.

Avoidance of Contact Lenses

Patients should be advised not to wear contact lenses if they have signs or symptoms of bacterial conjunctivitis.

Specific Populations

Pregnancy

Available data from published literature and postmarketing experience over several decades with azithromycin use in pregnant women have not identified any drug-associated risks for major birth defects, miscarriage, or adverse maternal or fetal outcomes . Developmental toxicity studies with azithromycin in rats, mice, and rabbits showed no drug-induced fetal malformations at doses up to 200 mg/kg/day. The doses used in these studies were orders of magnitude in excess of the clinical exposure that would be possible following topical ocular administration of azithromycin.

The estimated background risk of major birth defects and miscarriage for the indicated populations is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Available data from published observational studies, case series, and case reports over several decades do not suggest an increased risk for major birth defects, miscarriage, or adverse maternal or fetal outcomes with oral or topical ophthalmic azithromycin use in pregnant women. Limitations of these data include the lack of randomization and inability to control for confounders such as underlying maternal disease and maternal use of concomitant medications.

Lactation

Azithromycin is present in human milk. Non-serious adverse reactions have been reported in breastfed infants after maternal administration of oral azithromycin. There are no available data on the effects of azithromycin on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for azithromycin and any potential adverse effects on the breastfed infant from the drug.

Pediatric Use

The safety and effectiveness of azithromycin ophthalmic solution in pediatric patients have been established. The efficacy of azithromycin in treating bacterial conjunctivitis in pediatric patients has been demonstrated in controlled clinical trials.

Geriatric Use

No overall differences in safety or effectiveness have been observed between elderly and younger patients.

Common Adverse Effects

Most common adverse reaction reported in patients was eye irritation (1 to 2% of patients).

Drug Interactions

Specific Drugs

It is essential that the manufacturer's labeling be consulted for more detailed information on interactions with this drug, including possible dosage adjustments. Interaction highlights:

Please see product labeling for drug interaction information.

Actions and Spectrum

Mechanism of Action

Azithromycin is a macrolide antibiotic. Azithromycin acts by binding to the 50S ribosomal subunit of susceptible microorganisms and interfering with microbial protein synthesis. Azithromycin has been shown to be active against most isolates of the following microorganisms, both in vitro and clinically in conjunctival infections:

CDC coryneform group G
Haemophilus influenzae
Staphylococcus aureus
Streptococcus mitisgroup
Streptococcus pneumoniae

The following in vitro data are also available, but their clinical significance in ophthalmic infections is unknown. The safety and effectiveness of azithromycin ophthalmic solution in treating ophthalmological infections due to these microorganisms have not been established.

The following microorganisms are considered susceptible when evaluated using systemic breakpoints. However, a correlation between the in vitro systemic breakpoint and ophthalmological efficacy has not been established. This list of microorganisms is provided as an aid only in assessing the potential treatment of conjunctival infections. Azithromycin exhibits in vitro minimal inhibitory concentrations (MICs) of equal or less (systemic susceptible breakpoint) against most (≥90%) of isolates of the following ocular pathogens:

Chlamydia pneumoniae
Chlamydia trachomatis
Legionella pneumophila
Moraxella catarrhalis
Mycoplasma hominis
Mycoplasma pneumoniae
Neisseria gonorrhoeae
Peptostreptococcus species
Streptococci (Groups C, F, G)
Streptococcus pyogenes
Streptococcus agalactiae
Ureaplasma urealyticum
Viridans group streptococci

Advice to Patients

See FDA-Approved Patient Labeling (Patient Information and Instructions for Use).
Advise patients to avoid contaminating the applicator tip by not allowing it to touch the eye, fingers or other sources.
Direct patients to discontinue use and contact a physician if any signs of an allergic reaction occur.
Tell patients that although it is common to feel better early in the course of the therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by azithromycin ophthalmic solution or other antibacterial drugs in the future.
Advise patients not to wear contact lenses if they have signs or symptoms of bacterial conjunctivitis.
Advise patients to thoroughly wash hands prior to using azithromycin.
Advise patients to invert the closed bottle (upside down) and shake once before each use. Remove cap with bottle still in the inverted position. Tilt head back, and with bottle inverted, gently squeeze bottle to instill one drop into the affected eye(s).

Additional Information

AHFSfirstRelease^™. For additional information until a more detailed monograph is developed and published, the manufacturer's labeling should be consulted. It is essential that the manufacturer's labeling be consulted for more detailed information on usual uses, dosage and administration, cautions, precautions, contraindications, potential drug interactions, laboratory test interferences, and acute toxicity.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.