Aztreonam

Uses

Aztreonam is used for the treatment of the following infections caused by susceptible Gram-negative microorganisms:

• Urinary Tract Infections (complicated and uncomplicated), including pyelonephritis and cystitis (initial and recurrent) caused by Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella oxytoca, Citrobacter species and Serratia marcescens.
• Lower Respiratory Tract Infections, including pneumonia and bronchitis caused by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Haemophilus influenzae, Proteus mirabilis, Enterobacter species and Serratia marcescens.
• Septicemia caused by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Serratia marcescens and Enterobacter species.
• Skin and Skin-Structure Infections, including those associated with postoperative wounds, ulcers and burns caused by Escherichia coli, Proteus mirabilis, Serratia marcescens, Enterobacter species, Pseudomonas aeruginosa, Klebsiella pneumoniae and Citrobacter species.
• Intra-abdominal Infections, including peritonitis caused by Escherichia coli, Klebsiella species including K. pneumoniae, Enterobacter species including E. cloacae, Pseudomonas aeruginosa, Citrobacter species including C. freundii and Serratia species including S. marcescens.
• Gynecologic Infections, including endometritis and pelvic cellulitis caused by Escherichia coli, Klebsiella pneumoniae, Enterobacter species including E. cloacae and Proteus mirabilis.Aztreonam is used for adjunctive therapy to surgery in the management of infections caused by susceptible organisms.

Aztreonam is also used to associated treatment for these conditions: Bloodstream Infections, Bone and Joint Infections, Febrile Neutropenia, Gynaecological infection, Intra-Abdominal Infections, Lower Respiratory Tract Infection (LRTI), Osteomyelitis, Respiratory Symptoms caused by Cystic fibrosis, Pseudomonas aeruginosa infection, Septic Arthritis, Skin Infections, Urinary Tract Infection, Uncomplicated Gonorrhea

How Aztreonam works

The bactericidal action of aztreonam results from the inhibition of bacterial cell wall synthesis due to a high affinity of aztreonam for penicillin binding protein 3 (PBP3). By binding to PBP3, aztreonam inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins. It is possible that aztreonam interferes with an autolysin inhibitor.

Dosage

Aztreonam dosage

Adults: The recommended dosage for Urinary tract infections , Moderately severe systemic infections and Severe systemic or life-threatening infections is 500 mg or 1 g , 1 g or 2 g, 2 g every 8 or 12, 8 or 12 and 6 or 8 hourly respectively.

Children:The recommended dosage for Mild to moderate infections (Over 1 week) and Moderate to severe infections (2 years or older) is 30 mg/kg and 50 mg/kg every 6 and 6 or 8 hourly respectively.Maximum recommended dose for adult is 8 g per day.Maximum recommended dose for pediatric patient is 120 mg/kg/day.

Pediatric use:Dosage information is not yet available for new born less than one week.

Renal impairment in adult patients:The dosage of Aztreonam should be halved in patients with estimated creatinine clearances between 10 mL/min/1.73 m2 and 30 mL/min/1.73 m2 after an initial loading dose of 1 g or 2 g. When only the serum creatinine concentration is available, the following formula (based on sex, weight, and age of the patient) may be used to approximate the creatinine clearance (Clcr):-Males: Clcr = {weight (kg) × (140-age)} / {72 × serum creatinine (mg/dL)}.

Females: Clcr = 0.85 × above valueIn patients with severe renal failure (creatinine clearance less than 10 mL/min/1.73 m2), the usual dose of 500 mg, 1 g or 2 g should be given initially. The maintenance dose should be one-fourth of the usual initial dose given at the usual fixed interval of 6, 8 or 12 hours. For serious or life-threatening infections, in addition to the maintenance doses, one-eighth of the initial dose should be given after each hemodialysis session.

Direction for reconstitution1. For IV- Bolus injection : 6 to 10 mL- Infusion: 3 mL*2. For IM- Injection: 3 mL*Intravenous infusion: The reconstituted solution must be further diluted with an appropriate infusion solution to final concentration less than 2% w/v (at least 50 ml solution per gram of Aztreonam).Appropriate infusion solution may be 0.9% Sodium Chloride Injection BP, 5% Glucose Intravenous Infusion BP, 5% or 10% Mannitol Intravenous Infusion BP.

Administration

Intravenous administration

Bolus injection: The dose should be slowly injected directly into a vein, or the tubing of a suitable administration set, over a period of 3 to 5 minutes.

Infusion: Infusion should be completed within a 20 to 60 minutes period.Intramuscular administration.

The dose should be given by deep injection into a large muscle mass. Aztreonam is well tolerated and should not be admixed with any local anesthetic agent.

Intramuscular administration: The dose should be given by deep injection into a large muscle mass. Aztreonam is well tolerated and should not be administered with any local anesthetic agent. For each gram of Aztreonam add at least 3 ml water for injection BP and shake well.

Intravenous administration: A bolus injection may be used to initiate therapy. The dose should be slowly injected directly into a vein, or the tubing of a suitable administration set, over a period of 3 to 5 minutes.

For infusion: Each gram of Aztreonam should be initially constituted with at least 3 ml of water for injection BP. The resulting solution should be diluted with an appropriate infusion solution to a final concentration not exceeding 2% w/v (at least 50 ml solution per gram Aztreonam). The Aztreonam infusion should be administered over a 20-60 minute period. A number of intravenous solutions may be used as diluents for the administration of Aztreonam by intravenous infusion.These include sodium chloride injection, dextrose and mixed injections of sodium chloride and dextrose, Ringers and lactated Ringers injection,water for injection etc.

Side Effects

Local reactions such as phlebitis/thrombophlebitis following IV administration and discomfort/swelling at the injection site following IM administration may occur. Systemic reactions like diarrhea, nausea and/or vomiting, and rash may occur. Other side effects include anaphylaxis, angioedema, bronchospasm, pancytopenia, neutropenia, thrombocytopenia, anemia, eosinophilia, leukocytosis, thrombocytosis, abdominal cramps, dermatitis, urticaria, pruritus, hypotension, flushing, seizure, weakness, headache, fever, malaise may occur.

Precaution

In patients with impaired hepatic or renal function, appropriate monitoring is recommended during therapy.

Interaction

Concomitant administration of probenecid or furosemide and Aztreonam causes clinically insignificant increases in the serum levels of Aztreonam.

Food Interaction

Aztreonam Disease Interaction

Major: colitisModerate: hemodialysis, renal dysfunction

Volume of Distribution

• 12.6 L

Elimination Route

Less than 1% absorbed from the gastrointestinal tract following oral administration. Completely absorbed following intramuscular administration.

Half Life

The serum half-life of aztreonam averaged 1.7 hours (1.5 to 2.0) in subjects with normal renal function, independent of the dose. In elderly patients and in patients with impaired renal function, the mean serum half-life of aztreonam increased (4.7 to 6 hours and 2.1 hours, respectively).

Clearance

• 91 mL/min [healthy]

Elimination Route

In healthy subjects, aztreonam is excreted in the urine about equally by active tubular secretion and glomerular filtration. Urinary excretion of a single parenteral dose was essentially complete by 12 hours after injection.

Pregnancy & Breastfeeding use

Aztreonam is a Pregnancy Category B drug. There are no adequate and well-controlled studies in pregnant women. Aztreonam is excreted in human milk in concentrations less than 1%; consideration should be given to temporary discontinuation of nursing.

Contraindication

Aztreonam is contraindicated in patients with known hypersensitivity to Aztreonam or any other component in the formulation.

Special Warning

Renal Impairment: In patients with impaired renal function, the normal recommended initial dose should be given. This should be followed by maintenance doses as below:

Creatinine clearance (10–30 ml/min): Maintenance dose is half of the initial dose.

Creatinine clearance (Less than 10 ml/min): One quarter of the initial dose.

The normal dose interval should not be altered. In patients on haemodialysis, a supplementary one eighth of the initial dose should be given after each dialysis.

Recommended for children of one week and older. Aztreonam for injection should be administered intravenously to pediatric patients with normal renal function. There are insufficient data regarding intramuscular administration to pediatric patients or dosing in pediatric patients with renal impairment.

Acute Overdose

If necessary, Aztreonam may be cleared from the serum by hemodialysis and/or peritoneal dialysis.

Interaction with other Medicine

Concomitant administration of probenecid or furosemide and Aztreonam causes clinically insignificant increases in the serum levels of Aztreonam.

Storage Condition

Aztreonam solutions for IV infusion at concentrations not exceeding 2% w/v must be used within 48 hours following constitution if kept at controlled room temperature (15 - 30 °C) or within 7 days if refrigerated (2 - 8 °C).

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