Skip to Content

Aztreonam (Oral Inhalation)

Medically reviewed by Last updated on May 3, 2020.


(AZ tree oh nam)

Index Terms

  • Aztreonam

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution Reconstituted, Inhalation [preservative free]:

Cayston: 75 mg (1 mL) [arginine free]

Brand Names: U.S.

  • Cayston

Pharmacologic Category

  • Antibiotic, Monobactam


Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins (PBPs), which in turn inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls, thus inhibiting cell wall biosynthesis. Bacteria eventually lyse due to ongoing activity of cell wall autolytic enzymes (autolysins and murein hydrolases), while cell wall assembly is arrested. Monobactam structure makes cross-allergenicity with beta-lactams unlikely.


Low systemic absorption.


Urine (10% [compared with 60% to 65% for injection] as unchanged drug).

Time to Peak

~1 hour (plasma).

Half-Life Elimination

Adults: 2.1 hours.

Protein Binding


Use: Labeled Indications

Cystic fibrosis: Improve respiratory symptoms in cystic fibrosis (CF) patients with pulmonary Pseudomonas aeruginosa infections.


Hypersensitivity to aztreonam or any component of the formulation

Dosing: Adult

Cystic fibrosis: Inhalation (nebulizer): 75 mg 3 times daily (at least 4 hours apart) for 28 days; administer in repeated cycles of 28 days on drug, followed by 28 days off drug. Note: Pretreatment with a bronchodilator is recommended.

Dosing: Pediatric

Cystic fibrosis (Pseudomonas aeruginosa): Inhalation (nebulizer): Infants ≥3 months, Children, and Adolescents (limited data available in ages <7 years): 75 mg via nebulization 3 times daily (at least 4 hours apart) for 28 days; administer in repeated cycles of 28 days on drug, followed by 28 days off drug (Lahiri 2016; Tiddens 2015; manufacturer's labeling).


Reconstitute with 1 mL of sterile diluent (saline) immediately prior to use. Squeeze diluent into opened glass vial. Replace rubber stopper and gently swirl vial until contents have completely dissolved.


Administer using only an Altera nebulizer system; administer alone; do not mix with other nebulizer medications. Administer a bronchodilator before administration of aztreonam (short-acting: 15 minutes to 4 hours before; long-acting: 30 minutes to 12 hours before). For patients on multiple inhaled therapies, administer bronchodilator first, then mucolytic, and lastly, aztreonam.

To administer Cayston, pour reconstituted solution into the handset of the nebulizer system, turn unit on. Place the mouthpiece in the patient’s mouth and encourage to breathe normally through the mouth. Administration time is usually 2 to 3 minutes. Administer doses ≥4 hours apart.


Prior to reconstitution, store at 2°C to 8°C (36°F to 46°F). Once removed from refrigeration, aztreonam and the diluent may be stored at room temperature (up to 25°C [77°F]) for ≤28 days. Protect from light. Use immediately after reconstitution.

Drug Interactions

There are no known significant interactions.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.


Gastrointestinal: Pharyngolaryngeal pain (12%)

Respiratory: Cough (54%), nasal congestion (16%), wheezing (16%)

Miscellaneous: Fever (13%; more common in children)

1% to 10%:

Cardiovascular: Chest discomfort (8%)

Dermatologic: Skin rash (2%)

Gastrointestinal: Abdominal pain (7%), vomiting (6%)

Respiratory: Bronchospasm (3%; patients experienced ≥15% reduction in FEV1)

<1%, postmarketing, and/or case reports: Arthralgia, facial rash, facial swelling, hypersensitivity reaction, joint swelling, pharyngeal edema


Concerns related to adverse effects:

• Beta-lactam allergy: Rare cross-allergenicity to penicillins, cephalosporins, or carbapenems may occur; use with caution in patients with a history of hypersensitivity to beta-lactams.

• Bronchospasm: May occur following nebulization; administer a bronchodilator prior to treatment.

Dosage form specific issues:

• Appropriate use: Compare patient's baseline FEV1 prior to therapy and the presence of other symptoms when deciding if post-treatment FEV1 changes (eg, decline) are caused by a pulmonary exacerbation. Reserve use for cystic fibrosis (CF) patients with known Pseudomonas aeruginosa.

Monitoring Parameters

Consider measuring FEV1 prior to initiation of therapy

Pregnancy Considerations

Aztreonam crosses the placenta and reaches the fetal circulation following IV administration; however, peak plasma concentrations following inhalation of aztreonam are significantly less than those observed following aztreonam IV.

Due to its poor systemic absorption, use of aztreonam inhalation is likely acceptable for the management of cystic fibrosis in pregnant patients with Pseudomonas aeruginosa (Kroon 2018; Middleton 2019). When required, use may continue during pregnancy (Middleton 2019).

Patient Education

What is this drug used for?

• It is used in some people with cystic fibrosis to make breathing better.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Vomiting

• Stuffy nose

• Sore throat

• Abdominal pain

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Chest pain

• Persistent cough

• Trouble breathing

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.