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Aztreonam

Comprehensive Guide to Aztreonam: Uses, Dosage, Side Effects, and More

What is Aztreonam?

Aztreonam is a monobactam antibiotic used to treat severe bacterial infections, particularly those caused by Gram-negative bacteria. This medication inhibits bacterial cell wall synthesis, making it effective against pathogens like Pseudomonas aeruginosa. Marketed under the brand name Azactam and as generics, it is available as an intravenous or intramuscular injection. Aztreonam’s benefits include its utility in penicillin-allergic patients, but it requires monitoring for side effects like diarrhea or rash.

Overview

Generic Name: Aztreonam

Brand Name: Azactam, generics

Drug Group: Monobactam antibiotic

This medication is used to:

  • Treat complicated urinary tract infections (UTIs) caused by Gram-negative bacteria.
  • Manage lower respiratory tract infections, including pneumonia.
  • Address intra-abdominal infections and septicemia.
  • Off-label uses include cystic fibrosis exacerbations or neutropenic fever under specialist guidance.

Key Characteristics

Form: Powder for injection (500 mg, 1 g, 2 g) administered IV or IM.

Two vials of Aztreonam for injection, USP, showing 1 gram and 2 gram dosages, single-dose vials for IV or IM use after constitution, a common antibiotic.
Aztreonam (Azactam) for injection, available in 1 gram and 2 gram single-dose vials, is a monobactam antibiotic used intravenously or intramuscularly to treat various bacterial infections.

Mechanism: Inhibits peptidoglycan synthesis by binding to penicillin-binding proteins (PBPs), leading to bacterial cell lysis.

Approval: FDA-approved (1986 for Azactam) and EMA-approved for Gram-negative infections.

Indications and Uses of Aztreonam

Aztreonam is indicated for:

Complicated Urinary Tract Infections: Treats infections caused by Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis.

Lower Respiratory Tract Infections: Manages pneumonia or bronchitis due to Haemophilus influenzae or Pseudomonas aeruginosa.

Intra-Abdominal Infections: Addresses peritonitis or abscesses caused by Gram-negative pathogens.

Off-Label Uses: Used in cystic fibrosis patients with chronic Pseudomonas infections or as empiric therapy in neutropenic fever, guided by clinical studies.

Note: This drug is most effective against aerobic Gram-negative bacteria and should be combined with other antibiotics for mixed infections.

Dosage of Aztreonam

Important Note: The dosage of this monobactam must be prescribed by a healthcare provider. Dosing is adjusted based on infection severity, renal function, and patient response.

Dosage for Adults

Uncomplicated Infections: 1 g IV or IM every 8–12 hours.

Moderate to Severe Infections: 2 g IV every 6–8 hours, up to a maximum of 8 g/day.

Urinary Tract Infections: 500 mg to 1 g IV or IM every 8–12 hours.

Dosage for Children

1 month and older: 30 mg/kg IV every 6–8 hours, up to 120 mg/kg/day (maximum 8 g/day).

Neonates: 30 mg/kg IV every 8–12 hours, adjusted for gestational age and renal function.

Dosage for Pregnant Women

Pregnancy Category B: Limited data; use only if benefits outweigh risks. Consult an infectious disease specialist or obstetrician.

Dosage Adjustments

Renal Impairment:

  • CrCl 10–30 mL/min: Reduce to 50% of normal dose.
  • CrCl <10 mL/min: Reduce to 25% and monitor levels.

Hepatic Impairment: No adjustment needed, but monitor for toxicity.

Elderly: Start with lower doses (e.g., 1 g every 12 hours); adjust based on renal function.

Additional Considerations

  • Administer this active ingredient IV over 20–60 minutes or IM as a deep injection.
  • Monitor renal function and adjust dose if creatinine clearance changes.

How to Use Aztreonam

Administration: Reconstitute powder with sterile water or saline (e.g., 10 mL per 1 g) and administer IV over 20–60 minutes or IM; rotate injection sites to prevent irritation.

Timing: Dose every 6–12 hours as prescribed, maintaining consistent intervals.

Monitoring: Watch for signs of rash, diarrhea, or injection site reactions.

Additional Tips:

  • Use a new needle and syringe for each dose to prevent contamination.
  • Report severe abdominal pain or fever immediately.

Contraindications for Aztreonam

  • Patients with hypersensitivity to Aztreonam or other monobactams.
  • Patients with a history of severe allergic reactions to beta-lactam antibiotics (caution advised).

Warnings & Precautions for Aztreonam

General Warnings

Allergic Reactions: Risk of anaphylaxis or cross-reactivity with other beta-lactams; monitor for rash or swelling.

Clostridium difficile Infection: Diarrhea may indicate pseudomembranous colitis; discontinue if severe.

Renal Toxicity: Elevated creatinine or oliguria; monitor renal function.

Superinfection: Risk of fungal or resistant bacterial overgrowth; assess during prolonged use.

Neuromuscular Effects: Rare seizures or weakness; use cautiously in patients with renal impairment.

Use in Specific Populations

Pregnancy: Category B; limited human data; use only if necessary.

Breastfeeding: Excreted in breast milk; use with caution and monitor infant.

Elderly: Increased risk of renal side effects; adjust dose and monitor closely.

Children: Approved for 1 month and older; monitor growth and development.

Renal/Hepatic Impairment: Adjust dose in renal failure; monitor liver function if prolonged use.

Additional Precautions

  • Inform your doctor about kidney disease, allergies, or prior antibiotic reactions before starting this medication.
  • Avoid concurrent nephrotoxic drugs unless benefits outweigh risks.

Overdose and Management of Aztreonam

Overdose Symptoms

Overdose may cause:

  • Nausea, vomiting, or diarrhea.
  • Neuromuscular irritability (e.g., tremors, seizures).
  • Renal dysfunction or electrolyte imbalance.

Immediate Actions

Contact Emergency Services: Call 911 or seek immediate medical help.

Supportive Care: Provide hydration, monitor renal function, and administer anticonvulsants if seizures occur.

Monitor: Check creatinine clearance, electrolytes, and neurological status for 24–48 hours.

Additional Notes

  • Overdose is rare with proper dosing; store securely.
  • Report persistent symptoms (e.g., confusion, rash) promptly.

Side Effects of Aztreonam

Common Side Effects

  • Diarrhea (5–10%, often mild)
  • Injection site pain (5–8%, related to IM use)
  • Rash (3–7%, typically self-limiting)
  • Nausea (2–5%, manageable with food)

These effects may decrease with continued use.

Serious Side Effects

Allergic: Severe rash, swelling, or difficulty breathing (anaphylaxis).

Gastrointestinal: Persistent diarrhea with blood or mucus (C. difficile).

Renal: Reduced urine output or swelling (renal failure).

Neurological: Seizures or severe headache.

Additional Notes

  • Regular monitoring for renal function and allergic reactions is recommended.
  • Report any unusual symptoms (e.g., fever, jaundice) immediately.

Drug Interactions with Aztreonam

This active ingredient may interact with:

Aminoglycosides: Enhanced nephrotoxicity; monitor renal function if combined.

Probenecid: Increases Aztreonam levels by reducing renal excretion; adjust dose.

Warfarin: Potential increase in bleeding risk; monitor INR.

Loop Diuretics: May exacerbate renal effects; use cautiously.

Action: Provide your healthcare provider with a complete list of medications and supplements.

Patient Education or Lifestyle

Medication Adherence: Take this monobactam as prescribed to treat bacterial infections, completing the full course to prevent resistance.

Monitoring: Report diarrhea, rash, or reduced urine output immediately.

Lifestyle: Maintain hydration to support kidney function; avoid alcohol during treatment.

Diet: No specific restrictions; take with food if nausea occurs.

Emergency Awareness: Know signs of allergic reactions or severe infection; seek care if present.

Follow-Up: Schedule regular check-ups to assess infection resolution and renal function.

Pharmacokinetics of Aztreonam

Absorption: Poor oral bioavailability; peak plasma concentration at 1–2 hours post-IM, 30 minutes post-IV.

Distribution: Volume of distribution ~0.2 L/kg; 56–60% protein-bound; penetrates cerebrospinal fluid with inflammation.

Metabolism: Minimal hepatic metabolism; excreted largely unchanged.

Excretion: Primarily renal (60–70% unchanged via glomerular filtration); half-life 1.7–2.9 hours, extended in renal impairment.

Half-Life: 1.7–2.9 hours (up to 6–8 hours in severe renal failure).

Pharmacodynamics of Aztreonam

This drug exerts its effects by:

Binding to penicillin-binding protein 3 (PBP3), inhibiting peptidoglycan cross-linking in Gram-negative bacteria.

Causing cell wall weakening and lysis, effective against Pseudomonas aeruginosa and Enterobacteriaceae.

Offering a beta-lactam structure with low cross-reactivity to penicillins, ideal for allergic patients.

Demonstrating concentration-dependent killing, with efficacy enhanced by prolonged infusion in severe infections.

Storage of Aztreonam

Temperature: Store at 20–25°C (68–77°F); protect from moisture.

Protection: Keep in original carton until use to shield from light.

Safety: Store out of reach of children.

Disposal: Dispose of unused vials per local regulations or consult a pharmacist.

Frequently Asked Questions (FAQs)

Q: What does Aztreonam treat?
A: This medication treats UTIs, pneumonia, and intra-abdominal infections.

Q: Can this active ingredient cause diarrhea?
A: Yes, diarrhea is a risk; report persistent or bloody stools immediately.

Q: Is Aztreonam safe for children?
A: Approved for 1 month and older; consult a pediatrician.

Q: How is this drug taken?
A: Via IV or IM injection, as directed by a healthcare provider.

Q: How long is Aztreonam treatment?
A: Typically 7–14 days, depending on infection severity.

Q: Can I use Aztreonam if allergic to penicillin?
A: Often safe, but consult your doctor to confirm.

Regulatory Information

This medication is approved by:

  • U.S. Food and Drug Administration (FDA): Approved in 1986 (Azactam) for Gram-negative infections.
  • European Medicines Agency (EMA): Approved for similar indications.
  • Other Agencies: Approved globally for bacterial infections; consult local guidelines.

References

  1. U.S. Food and Drug Administration (FDA). (2023). Azactam (Aztreonam) Prescribing Information.
    • Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
  2. European Medicines Agency (EMA). (2023). Aztreonam Summary of Product Characteristics.
    • EMA’s comprehensive information on the medication’s indications and precautions in Europe.
  3. National Institutes of Health (NIH). (2023). Aztreonam: MedlinePlus Drug Information.
    • NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
  4. World Health Organization (WHO). (2023). WHO Model List of Essential Medicines: Aztreonam.
    • WHO’s inclusion of Aztreonam for severe bacterial infections.
  5. Journal of Antimicrobial Chemotherapy. (2021). Aztreonam in Gram-Negative Infections.
    • Peer-reviewed article on Aztreonam efficacy (note: access may require a subscription).
Disclaimer: This article provides general information about Aztreonam for educational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare provider, such as an infectious disease specialist or primary care physician, before using this drug or making any medical decisions. Improper use of this active ingredient can lead to serious health risks, including bacterial resistance or allergic reactions.

 

Dr. Andrew Parker is a board-certified internal medicine physician with over 10 years of clinical experience. He earned his medical degree from the University of California, San Francisco (UCSF), and has worked at leading hospitals including St. Mary’s Medical Center. Dr. Parker specializes in patient education and digital health communication. He now focuses on creating clear, accessible, and evidence-based medical content for the public.

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