Mechanism of action (Pharmacodynamics)
Nitroxoline exhibits a pronounced bacteriostatic effect. This means that the drug does not cause immediate death of the microorganism, but reliably halts its further growth and reproduction. Pharmacodynamics is based on two key sites of action:
- Selective inhibition of DNA synthesis: the active substance selectively blocks the formation of new bacterial DNA chains. Without duplication of genetic material, the microbial cell loses its ability to divide.
- Chelation (formation of complexes with metals): the drug binds to metal ions, which are essential components for the functioning of vital bacterial enzymes. By forming such stable complexes, nitroxoline disrupts the functioning of the microbial cell's enzyme systems, blocking its metabolism.
Antimicrobial spectrum
One of the main advantages of the drug is its broad antimicrobial spectrum. Unlike many highly specific agents, nitroxoline suppresses the activity of not only typical bacteria, but also a number of other pathogens.
- Gram-positive bacteria: the drug is effective against staphylococci, various species of streptococci (including pneumococci and enterococci), and also successfully suppresses the causative agent of diphtheria.
- Gram-negative bacteria: the spectrum of action includes the main causative agents of intestinal and urological infections — Escherichia coli, Salmonella, Shigella, Klebsiella, Proteus, and Enterobacter.
- Other microorganisms: 8-hydroxyquinoline derivatives are active against Mycobacterium tuberculosis. In addition, they act on protozoa (specifically, Trichomonas) and possess an antifungal effect, suppressing yeast-like fungi of the genus Candida and dermatophytes.
Pharmacokinetics and Clinical Application
A key feature of nitroxoline that determines its place in medicine lies in its pharmacokinetic profile. After oral administration, the drug demonstrates rapid and complete absorption from the gastrointestinal tract.
The most important thing for the clinician is its route of elimination. The drug is excreted by the kidneys unchanged. Due to this, extremely high concentrations of the active substance are created in the urine. This exact fact determines the primary profile of clinical application:
- Therapy: treatment of infectious and inflammatory diseases of the urinary tract, such as cystitis, urethritis, and pyelonephritis.
- Prophylaxis: prevention of infectious complications after surgical interventions on the kidneys and urinary tract structures.
Side effects and administration features
When prescribing nitroxoline, the attending physician must be aware of potential adverse reactions and inform the patient in advance about certain specific effects.
- Specific sign: during therapy, the patient's urine turns a rich saffron-yellow color. This is an absolutely normal consequence of drug elimination, but without prior warning, such a symptom may cause severe anxiety in the patient.
- Dyspeptic disorders: nausea and various digestive disturbances may occur from the gastrointestinal tract.
- 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 is capable of provoking allergic responses.
Association for the drug 5-NOX (Nitroxoline): Excreted unchanged by kidneys, Yellow (saffron-yellow) urine coloration, Chelates metals (enzyme complexation). Spectrum includes 5 groups: Gram(+), Gram(-), Mycobacterium tuberculosis, fungi, and protozoa.
Class and exam questions
Why is nitroxoline used specifically for urinary tract infections?
The drug is excreted by the kidneys unchanged. This makes it very high, therapeutically effective concentrations of the active substance in the urine, which are lethal to uropathogens.
What must a patient be warned about at an appointment before prescribing 5-NOX?
The patient must be warned that while taking the drug, the urine will acquire a bright saffron-yellow color. This is a safe specific sign that does not require discontinuation of treatment.
What is the mechanism of the bacteriostatic action of 8-hydroxyquinoline derivatives?
The drug selectively inhibits bacterial DNA synthesis and chelates metals that are part of microbial enzymes, which leads to disruption of their work and cessation of cell reproduction.
Does nitroxoline affect fungal flora?
Yes, the antimicrobial spectrum of the drug includes yeast-like fungi of the genus Candida and dermatophytes, which distinguishes it from many narrowly targeted antibacterial agents.
What else to study on this topic
- The mechanism of metal chelation in pharmacology
- Comparative characteristics of bacteriostatic and bactericidal action
- The role of enterococci and klebsiella in the development of urinary tract infections
- Neurological side effects of antimicrobial agents (ataxia and paresthesias)
- Prevention of postoperative infections in urology
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