Schedule H

Intravenous (IV), Intramuscular (IM)

Powder for Injection:

• Aztreonam 500 mg per vial

• Aztreonam 1 g per vial

• Aztreonam 2 g per vial

Inhalation Formulation (Aztreonam lysine): NOT AVAILABLE in India

Note: Aztreonam requires reconstitution before administration. Reconstitute with sterile water for injection or compatible IV fluid.

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

1. Complicated Urinary Tract Infections / Pyelonephritis

Parameter Dosing Details

Starting dose 1 g IV/IM every 8–12 hours

Titration Increase to 2 g every 8 hours for severe infection

Usual maintenance dose 1–2 g IV every 8–12 hours

Maximum dose 8 g/day

Key Clinical Notes:

• Excellent activity against aerobic Gram-negative organisms including Pseudomonas aeruginosa

• Achieves high urinary concentrations

• Duration: 7–14 days based on clinical response

• IM route acceptable for moderate infections; IV preferred for severe

1. Lower Respiratory Tract Infections (Gram-negative, including HAP/VAP)

Parameter Dosing Details

Starting dose 1–2 g IV every 8 hours

Titration Not applicable

Usual maintenance dose 2 g IV every 8 hours

Maximum dose 8 g/day

Key Clinical Notes:

• Covers Pseudomonas aeruginosa and other aerobic Gram-negatives

• NO Gram-positive or anaerobic coverage — must combine with appropriate agents for polymicrobial pneumonia

• Duration: 7–14 days based on clinical response and culture results

1. Septicaemia / Bloodstream Infections (Gram-negative)

Parameter Dosing Details

Starting dose 2 g IV every 6–8 hours

Titration Not applicable

Usual maintenance dose 2 g IV every 6–8 hours

Maximum dose 8 g/day

Key Clinical Notes:

• Use IV route only for sepsis (IM not appropriate)

• First dose should not be delayed for cultures

• Administer as IV infusion over 20–60 minutes

• De-escalate based on culture sensitivity at 48–72 hours

1. Complicated Intra-abdominal Infections

Parameter Dosing Details

Starting dose 2 g IV every 8 hours

Titration Not applicable

Usual maintenance dose 2 g IV every 8 hours

Maximum dose 8 g/day

Key Clinical Notes:

• MUST combine with metronidazole or clindamycin — aztreonam has NO anaerobic activity

• MUST add Gram-positive coverage (vancomycin or alternative) if Gram-positive involvement suspected

• Duration: 4–7 days with adequate source control

1. Skin and Soft Tissue Infections (Gram-negative)

Parameter Dosing Details

Starting dose 1–2 g IV every 8 hours

Titration Not applicable

Usual maintenance dose 2 g IV every 8 hours

Maximum dose 8 g/day

Key Clinical Notes:

• Use only when Gram-negative coverage specifically required (e.g., ecthyma gangrenosum, burn wound infections)

• Add Gram-positive coverage for polymicrobial soft tissue infections

• NOT for cellulitis or streptococcal/staphylococcal skin infections

1. Gynaecological Infections (Gram-negative Component)

Parameter Dosing Details

Starting dose 1–2 g IV every 8–12 hours

Titration Not applicable

Usual maintenance dose 1–2 g IV every 8 hours

Maximum dose 8 g/day

PAEDIATRIC DOSING (Specialist Only)

Primary Indications

Same indications as adults: Gram-negative UTI, pneumonia, sepsis, intra-abdominal infections

⚠️ Use under paediatric infectious disease specialist supervision

Age-Based Dosing:

Neonates 0–7 days 30 mg/kg IV Every 12 hours 60 mg/kg/day

Neonates 8–28 days 30 mg/kg IV Every 8 hours 90 mg/kg/day

Infants 1–12 months 30 mg/kg IV Every 6–8 hours 120 mg/kg/day

Children 1–12 years 30–50 mg/kg IV Every 6–8 hours 120 mg/kg/day (max 8 g/day)

Adolescents ≥12 years Adult dosing — 8 g/day

Indication-Specific Paediatric Dosing:

Indication Dose Notes

Moderate infections (UTI, pneumonia) 30 mg/kg IV every 8 hours Max 1 g/dose

Severe infections (sepsis) 50 mg/kg IV every 6–8 hours Max 2 g/dose

Cystic fibrosis exacerbation 50 mg/kg IV every 6–8 hours Max 8 g/day; specialist only

Key Clinical Notes:

• Administer as IV infusion over 20–30 minutes

• IM route may be used for moderate infections in older children

• Adjust dose for renal impairment

Secondary Indications — Paediatric (Off-label)

Indication Dose Duration Notes

Febrile Neutropenia (β-lactam allergic) (OFF-LABEL) 50 mg/kg IV every 6–8 hours (max 2 g/dose) Until ANC recovery Specialist only. Safe in β-lactam allergy. Combine with vancomycin.

Clear Statement: Neonatal use requires neonatologist/NICU supervision. Safe for use from birth with appropriate weight-based dosing and renal function monitoring.

Safety Monitoring in Children:

• Renal function at baseline and during therapy

• LFTs if therapy >7 days

• CBC weekly for prolonged therapy

• Monitor for diarrhoea and GI symptoms

Creatinine Clearance (mL/min) Initial Dose Maintenance Dose Notes

30 Standard dose No adjustment

10–30 Standard loading dose 50% of usual dose; maintain interval OR give usual dose at extended interval

<10 (not on dialysis) Standard loading dose 25% of usual dose; maintain interval

Haemodialysis Standard loading dose 500 mg–1 g after each dialysis session Moderately dialysable (~25–50% removed)

CAPD Standard loading dose 25% of usual dose every 12 hours

CRRT (CVVH/CVVHDF) Standard loading dose 1–2 g every 8–12 hours Adjust based on effluent rate

• Known hypersensitivity to aztreonam

• History of severe allergic reaction (anaphylaxis) to aztreonam

Note on β-lactam cross-reactivity: Aztreonam has a unique monocyclic β-lactam structure with minimal cross-reactivity with penicillins, cephalosporins, or carbapenems. It is generally SAFE in patients with IgE-mediated penicillin/cephalosporin allergy. However, cross-reactivity with ceftazidime exists due to identical R1 side chain — avoid in patients with documented ceftazidime allergy.

• History of allergy to ceftazidime — cross-reactivity possible due to shared side chain

• Renal impairment — mandatory dose adjustment; neurotoxicity risk with accumulation

• History of seizures — increased risk with high doses or renal impairment

• History of Clostridioides difficile infection or antibiotic-associated colitis

• Prolonged therapy — risk of superinfection with Gram-positive organisms or fungi

• Limited spectrum — NO activity against Gram-positive organisms or anaerobes; do NOT use as monotherapy for mixed infections

• Elderly patients — often have reduced renal function; calculate CrCl

Parameter Details

Risk Category Generally considered safe; limited human data but no evidence of teratogenicity in animal studies

Preferred alternatives Cephalosporins (ceftriaxone, cefotaxime) preferred when tolerated. Aztreonam reserved for patients with β-lactam allergy.

When may be used When Gram-negative coverage specifically required and patient has severe penicillin/cephalosporin allergy

Monitoring Monitor maternal renal function; no specific fetal monitoring required

Parameter Details

Compatibility Compatible with breastfeeding

Preferred alternatives None required; aztreonam acceptable during lactation

Drug levels in milk Low (<1% of maternal dose reaches breast milk)

Infant monitoring Monitor for diarrhoea, oral thrush; no need to interrupt breastfeeding

Parameter Recommendation

Starting dose Standard adult dosing, but MUST calculate creatinine clearance (CrCl) using Cockcroft-Gault formula

Titration Adjust based on renal function; serum creatinine may underestimate renal impairment in elderly

Special risks Neurotoxicity (confusion, seizures) with dose accumulation in renal impairment; C. difficile colitis risk increased; superinfection with Gram-positives

Monitoring Baseline and serial renal function; neurological assessment if high doses or renal impairment

Interacting Drug Mechanism & Effect Management

Aminoglycosides (concurrent administration) Physical incompatibility in IV line (inactivation); potential additive nephrotoxicity Do NOT mix in same IV line. Flush between drugs. Monitor renal function daily.

Probenecid Inhibits renal tubular secretion; increases aztreonam serum levels Avoid combination; if used, monitor for toxicity

Vancomycin Physical incompatibility in IV line Administer separately; flush line between drugs

Chloramphenicol Potential antagonism (bacteriostatic vs bactericidal) Avoid combination for serious infections

Interacting Drug Effect Management

Loop Diuretics (Furosemide, high-dose) Potential additive nephrotoxicity Monitor renal function

Oral Anticoagulants (Warfarin) Possible INR elevation (rare; mechanism unclear — altered gut flora) Monitor INR during and after therapy

Live Vaccines (BCG, Typhoid oral) Antibiotic may reduce vaccine efficacy Avoid live vaccines during therapy

Other Nephrotoxic Drugs Additive nephrotoxicity Monitor renal function

• Diarrhoea

• Injection site reactions (pain, phlebitis, swelling)

• Rash (maculopapular)

• Nausea, vomiting

• Elevated hepatic transaminases (transient)

• Eosinophilia

Adverse Effect Clinical Notes

Anaphylaxis / Severe Hypersensitivity Rare (aztreonam generally well-tolerated even in β-lactam allergic patients). Discontinue immediately; emergency management.

Clostridioides difficile-Associated Diarrhoea (CDAD) Can occur during or weeks after therapy; discontinue if severe; treat appropriately

Seizures / Neurotoxicity Risk factors: renal impairment, high doses, elderly. Discontinue; usually reversible.

Blood Dyscrasias (neutropenia, thrombocytopenia, eosinophilia) With prolonged therapy (>2 weeks); monitor CBC; usually reversible

Hepatotoxicity (cholestatic hepatitis) Rare; monitor LFTs in prolonged therapy; discontinue if significant elevation

Superinfection Gram-positive or fungal superinfection due to narrow spectrum; monitor for new fever, new site of infection

During treatment Renal function every 2–3 days (ICU) or twice weekly (ward); daily assessment for hypersensitivity (first 48 hours); monitor for diarrhoea

Prolonged therapy (>7 days) CBC weekly; LFTs weekly; assess for superinfection

Special populations In elderly/renal impairment: neurological assessment for signs of neurotoxicity

Plain Aztreonam:

• Azactam® (Bristol-Myers Squibb) — originator

• Azinam® (Lupin)

• Aztreonam® (Glenmark)

• Ztreonam® (Unichem)

• Azirest® (Aristo)

• Aztreo® (various generics)

Note: Only injectable formulations available in India. Inhaled aztreonam (Cayston®) for cystic fibrosis is NOT marketed in India.

Note: Aztreonam is NOT listed in NLEM 2022. Not under NPPA price ceiling. Prices vary significantly by brand. Limited government supply; primarily available through private pharmacy channels.

1. Safe in severe β-lactam allergy — Aztreonam has minimal cross-reactivity with penicillins, cephalosporins, and carbapenems. It is the preferred option for Gram-negative coverage in patients with documented IgE-mediated (anaphylactic) penicillin or cephalosporin allergy.

1. Exception: Ceftazidime allergy — Aztreonam and ceftazidime share an identical R1 side chain, creating potential cross-reactivity. Avoid aztreonam in patients with documented ceftazidime allergy.

1. Gram-negative ONLY — Aztreonam has NO activity against Gram-positive organisms (Staphylococcus, Streptococcus, Enterococcus) or anaerobes. Never use as monotherapy for polymicrobial infections — always combine with appropriate agents.

1. Not a substitute for broad-spectrum β-lactams — Aztreonam's narrow spectrum makes it unsuitable for empiric therapy in most situations. Reserve for targeted therapy or when β-lactam allergy precludes other options.

1. Excellent anti-pseudomonal activity — Comparable to ceftazidime for Pseudomonas aeruginosa. Consider for Pseudomonas infections in β-lactam allergic patients.

1. Renal dosing is critical — Aztreonam accumulation in renal impairment can cause neurotoxicity. Always calculate CrCl and adjust dose appropriately.

monobactam; Gram-negative; Pseudomonas; beta-lactam-allergy-safe; penicillin-allergy-safe; sepsis; ICU-antibiotic; renal-dose-adjust; Schedule-H; narrow-spectrum; Aztreonam

RxIndia v1.0 — 06 Jun 2025

• CDSCO Drug Database

• Indian Pharmacopoeia 2022

• National Formulary of India (NFI) 2021

• API Textbook of Medicine (11th Edition)

• ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes (2019)

• AIIMS Antibiotic Policy (2023)

• PGIMER Chandigarh Antimicrobial Guidelines

• IAP Drug Formulary — Paediatric Dosing

• Harrison's Principles of Internal Medicine (21st Edition)

• Goodman & Gilman's The Pharmacological Basis of Therapeutics (14th Edition)

• Product package inserts (Azactam®)

• WHO Model List of Essential Medicines (supportive — paediatric data)