#azactam

Common Brand Names: Azactam

Therapeutic Class: A monobactam antibiotic

Common Injectable Dosage Forms:

Powder for Injection (Lyophilized cake): 500 mg, 1 g, 2 g as either vials for injection or 100 mL infusion bottles

Frozen Premixed Solution: 1 g, 2 g

Dosage Ranges:

For the treatment of lower respiratory tract infections (including pneumonia and bronchitis), septicemia, skin and skin structure infections (including those associated with postoperative wounds or ulcers or burns), intra-abdominal infections (including peritonitis), and gynecologic infections (including endometritis and pelvic cellulitis) caused by susceptible gram-negative bacteria: 1-2 g every 8-12 hours.

For the treatment of complicated and uncomplicated urinary tract infections (including pyelonephritis and cystitis): 500 mg or 1 g every 8-12 hours.

For the treatment of moderately severe systemic infections: Adults should receive 1-2 g every 8-12 hours. Severe systemic or life-threatening infections, especially those involving P. aeruginosa, may require 2 g every 6-8 hours. The maximum adult dosage recommended is 8 g/day.

Pediatric dosage (1 month to 15 years) has been established at 30-59 mg/kg every 4-8 hours.

Administration and Stability: For direct IV injection, the dose should be diluted with 6-10 mL of diluent and injected over a period of 3-5 minutes. For intermittent IV fusion, aztreonam should be diluted with a compatible solution to a final concentration not exceeding 20 mg/mL and infused over a period of 20-60 minutes. For IM injection at least 3 mL of an appropriate diluent should be added per gram of aztreonam and injected deeply into a large muscle. pH: 4.5-7.5

Pharmacology/Pharmacokinetics: Aztreonam is a synthetic monobactam antibiotic that exhibits its bactericidal effect by inhibiting bacterial cell wall synthesis. Aztreonam is active against many gram-negative bacteria, including most Enterobacteriaceae and P. aeruginosa, but has little or no activity against gram-positive or anaerobic bacteria. Aztreonam is 100% bioavailable when given IM, producing peak serum levels in 1 hours. The drug is excreted primarily unchanged in the urine and has an elimination half-life of 1.7 hours, which is prolonged in renal failure, requiring dosage adjustments.

Drug and Lab Interactions: Aztreonam, like most cephalosporins, can produce false-positive Benedict’s test for urine glucose. The antibacterial activity is additive or synergistic with aztreonam is combined with other antibiotics such as aminoglycosides, beta-lactams, and clindamycin, and should always be used in combination in the treatment of mixed infections, or those of unknown etiology, to ensure coverage gram-positive and anaerobic bacteria.

Contraindications/Precautions: Care should be taken to determine if patients have any previous history of hypersensitivity to any beta-lactams, as some degree of cross-sensitivity has been demonstrated. Aztreonam appears to lack the nephrotoxic effects seen with aminoglycosides, but elevations in hepatic function tests have been frequent. As with other antibiotics, superinfections are a concern during aztreonam therapy. Pregnancy Category B.

Monitoring Parameters: LFTs, BUN, Cr

Adverse Effects: Nausea, vomiting, diarrhea, and other GI effects have been reported with aztreonam therapy. Skin rash, phlebitis, and blood dyscrasias have also been reported as other adverse effects associated with the use of aztreonam.