Pharmacokinetics of Aztreonam

Study Notes

Common: gastric distress, diarrhea, nausea/vomiting, hypersensitivity, and thrombophlebitis at the injection site
Rare: anaphylaxis, hepatitis, jaundice, thrombocytopenia, and prolonged bleeding time
Caution: low risk of allergic reaction in those allergic to penicillins or cephalosporins

Includes: amikacin, gentamycin, tobramycin, and neomycin (oral)
Mechanism of Action: bind irreversibly to the 30S ribosomal subunit, inhibiting protein synthesis and leading to cell death
Indications: serious or life-threatening Gram-negative infections, especially those caused by Pseudomonas, E. coli, Proteus, Klebsiella, Serratia, and enterococci
Pharmacokinetics:
- Strongly polar molecules, do not distribute to the CNS
- Tissue concentrations are low
- Eliminated by the kidneys in people with normal renal function
- Plasma half-life: 2-3 hours
- Monitoring plasma concentrations is essential to ensure therapeutic concentrations without adverse reactions

Bacteriostatic agent effective against Gram-negative and Gram-positive organisms and anaerobes
Indications: Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis
Contraindications: pre-existing bone marrow suppression and/or blood dyscrasias
Mechanism of Action: inhibits protein synthesis by binding to the 50S sub-unit of the bacterial ribosome

Includes: lincomycin and clindamycin
Mechanism of Action: inhibits protein synthesis by binding to the 50S ribosomal sub-unit and preventing peptide bond formation
Indications: serious streptococcal and staphylococcal infections
Pharmacokinetics:
- Half-life in adults: 2-3 hours
- Reaches peak blood concentrations within 0.75-1 hour of oral administration in adults, 1 hour in children, and 3 hours after IM injection
- May cause thrombocytopenia, leucopenia, eosinophilia, and neutropenia; full blood count should be monitored during therapy

Includes: doxycycline, minocycline, and tetracycline
Mechanism of Action: inhibits protein synthesis by reversibly blocking the 30S sub-unit of the ribosome and preventing access of tRNA to the mRNA-ribosome complex
Indications: acne vulgaris, actinomycosis, anthrax, bacterial urinary tract infections (UTIs), bronchitis, and numerous systemic bacterial infections
Adverse Reactions:
- Common: dizziness (minocycline), esophagitis (doxycycline), ataxia, gastrointestinal distress, photosensitivity, discoloration of infants' or children's teeth
- Rare: hepatotoxicity, pancreatitis, and benign intracranial hypertension

Includes: ciprofloxacin, moxifloxacin, norfloxacin, and ofloxacin
Mechanism of Action: interferes with bacterial topoisomerase II (DNA gyrase) and topoisomerase IV, essential for DNA duplication, transcription, and repair
Indications: bone and joint infections, Legionella pneumonia, epididymo-orchitis, prostatitis, and complicated UTIs
Combination with trimethoprim is synergistic, blocking a further step in folic acid synthesis

Used to treat UTIs
Mechanism of Action: formaldehyde is released, which may be bactericidal or bacteriostatic, causing denaturation of bacterial protein
Effective in acid medium, ineffective in alkaline urine
Indications: long-term suppression of infections, due to its low toxicity and low incidence of resistance

Bactericidal agent effective against E. coli and S. aureus
Mechanism of Action: reduced by bacteria to reactive substances that inactivate or alter cell wall synthesis, bacterial ribosomal proteins, and DNA and RNA function
Indications: acute UTIs and prophylaxis of recurrent UTIs
Pharmacokinetics:
- Well absorbed
- Half-life: 20-60 minutes
- 65% excreted, mainly as unchanged drug in the urine
Adverse Effects:
- Acute allergic pneumonitis
- Rarely, chronic irreversible interstitial pulmonary fibrosis in older patients following chronic treatment (>6 months)
- Contraindications: nitrofurantoin hypersensitivity, peripheral neuropathy, lung disease, or moderate-to-severe renal impairment