Antibiotics (Properties, Applications, Interactions) - Posokhova K.A., Viktorov O.P. 2005

Penicillins
Monobactams

The structural feature of monobactam Antibiotics lies in the fact that their core is based on a simple ß-lactam ring, which, unlike Penicillins and Cephalosporins, is not fused to a thiazolidine ring.

Aztreonam (azactam) is a monobactam antibiotic with limited clinical use. It is active exclusively against Gram-negative Bacteria, particularly the family Enterobacteriaceae, including Escherichia coli, Klebsiella, Proteus, and Pseudomonas aeruginosa. However, staphylococci, pneumococci, S. faecalis, S. pyogenes, bacteroids, and other anaerobes are virtually resistant to it. Against Gram-negative bacteria, the efficacy of aztreonam is identical to that of third-generation cephalosporins. It is resistant to beta-lactamases.

Pharmacokinetics. Approximately 20% of the drug is absorbed from the gastrointestinal tract. It is most commonly administered parenterally. It penetrates well into all Tissues, including across the Blood-Brain barrier (in meningitis). It is excreted mainly unchanged in the urine.

Clinical Use. For hospital-acquired infections of various localizations caused by Gram-negative microorganisms, aztreonam is often combined with Aminoglycosides, clindamycin, metronidazole, and vancomycin. For Urinary Tract infections, it is used as an empirical therapy agent.

Aztreonam is administered intravenously or intramuscularly at a dose of 1.0–2.0 g 4 times a day; for infectious processes caused by P. aeruginosa, the dose is 2.0–3.0 g 4 times a day.

Side Effects. Allergic reactions (urticaria, Skin pruritus, erythema, eosinophilia, arthralgia, vasculitis, angioedema, bronchospasm, anaphylactic Shock) are observed less frequently than with penicillins and cephalosporins. Nausea, vomiting, and diarrhea may occur, but intestinal dysbiosis is less pronounced than during Treatment with cephalosporins. At the same time, cases of vaginal candidiasis and pseudomembranous colitis have been reported. Intravenous administration of aztreonam may cause phlebitis. Headaches, dizziness, thrombocytopenia, leukopenia, and hepatic and Renal Dysfunction are observed rarely.

Interactions. Synergism is observed between aztreonam and aminoglycosides. Pharmaceutical incompatibility exists between aztreonam and heparin or other beta-lactam antibiotics (they must not be mixed in solutions). Given the rarity of cross-allergy between aztreonam and penicillins or cephalosporins, it can be used with caution, if necessary, in patients sensitized to these antibiotics.