Mechanism of Action (Pharmacodynamics)
Nitroxoline exerts a pronounced bacteriostatic effect. This means the drug does not cause immediate microbial cell death, but rather reliably halts their continued growth and reproduction. Its pharmacodynamics are based on two key targets:
- Selective inhibition of DNA synthesis: The active substance selectively blocks the formation of new bacterial DNA chains. Without genetic material duplication, the microbial cell loses its ability to divide.
- Chelation (metal-complex formation): The drug binds to metal ions, which serve as essential components for the functioning of vital bacterial enzymes. By forming stable complexes, nitroxoline disrupts the enzyme systems of the microbial cell, blocking its metabolism.
Antimicrobial Spectrum
One of the drug's major advantages is its broad antimicrobial spectrum. Unlike many highly specialized agents, nitroxoline suppresses the activity of not only typical bacteria but also several other pathogens.
- Gram-positive bacteria: The drug is effective against staphylococci, various streptococci species (including pneumococci and enterococci), and successfully suppresses the diphtheria bacillus.
- Gram-negative bacteria: The spectrum includes major intestinal and urological pathogens — Escherichia coli, Salmonella, Shigella, Klebsiella, Proteus, and Enterobacter.
- Other microorganisms: 8-hydroxyquinoline derivatives are active against Mycobacterium tuberculosis. Additionally, they affect protozoa (specifically Trichomonas) and exhibit antifungal effects, inhibiting yeast-like fungi of the genus Candida and dermatophytes.
Pharmacokinetics and Clinical Application
The key feature of nitroxoline that determines its role in medicine lies in its pharmacokinetic profile. Following oral administration, the drug demonstrates rapid and complete absorption from the gastrointestinal tract.
Most importantly for the clinician is its excretion pathway. The drug is excreted by the kidneys unchanged. Due to this, extremely high concentrations of the active substance are achieved in the urine. This exact fact defines its primary clinical indications:
- Therapy: Treatment of infectious and inflammatory diseases of the urinary tract, such as cystitis, urethritis, and pyelonephritis.
- Prophylaxis: Prevention of infectious complications following surgical procedures on the kidneys and urinary tract structures.
Adverse Effects and Administration Considerations
When prescribing nitroxoline, the physician must keep potential adverse reactions in mind and inform the patient in advance about specific effects.
- Specific sign: During therapy, the patient's urine turns a saturated saffron-yellow color. This is an entirely normal consequence of drug excretion; however, without prior warning, this symptom can cause significant patient anxiety.
- Dyspeptic disorders: Gastrointestinal disturbances such as nausea and various digestive upsets may occur.
- Neurological disorders: In rare cases, the drug can affect the nervous system, causing ataxia (impaired coordination of movements) and paresthesias (sensory disturbances).
- Allergic reactions: Like any synthetic agent, nitroxoline can provoke allergic responses.