NETAZOX OF

Mechanism of action

The most widely accepted mechanism of nitazoxanide is the disruption of energy metabolism in anaerobic microbes by inhibition of the pyruvate:ferredoxin/flavodoxin oxidoreductase (PFOR) cycle. It induces lesions in cell membranes and depolarizes the mitochondrial membrane, inhibiting enzymes such as quinone oxidoreductase NQO1, nitroreductase-1, and protein disulfide isomerase. Additionally, it inhibits glutathione-S-transferase, modulates the Avr-14 gene in nematodes, and exhibits various antibacterial mechanisms, including inhibition of pyruvate dehydrogenase in E. coli and disruption of Mycobacterium tuberculosis membrane potential. Nitazoxanide also suppresses viral replication by inhibiting maturation of viral hemagglutinin and activating antiviral intracellular proteins.

Pharmacodynamics

Nitazoxanide prevents microbial activity by disrupting essential energy pathways necessary for survival and proliferation. It exhibits antiprotozoal activity by interfering with the PFOR-dependent electron transfer reaction, crucial for anaerobic energy metabolism. This interference inhibits the sporozoites of Cryptosporidium parvum and trophozoites of Giardia lamblia, relieving diarrhea symptoms. The disruption of the PFOR enzyme-dependent reaction is one of several pathways through which nitazoxanide exerts its antiprotozoal effects.

Pharmacokinetics

Nitazoxanide is rapidly absorbed and extensively metabolized in the liver to its active metabolite, tizoxanide. The drug is excreted primarily in the urine and feces. The pharmacokinetics of nitazoxanide can be influenced by factors such as age, liver function, and co-administration of other medications. The half-life of nitazoxanide is approximately 1 to 3 hours, while tizoxanide has a longer half-life, allowing for

Adverse effects

• Abdominal pain
• Diarrhea
• Nausea
• Headache
• Dizziness

Precautions

• Use with caution in patients with hepatic impairment
• Monitor for gastrointestinal side effects

Pregnancy

Nitazoxanide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Data on the use of nitazoxanide in pregnant women is limited.

Breast-feeding

It is not known whether nitazoxanide is excreted in human milk. Caution should be exercised when administering to breastfeeding women.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• Oral suspension
• Tablet

Indications

• Bacterial infections
• Complicated urinary-tract infections
• Lower respiratory-tract infections
• Skin infections
• Gonorrhoea
• Pelvic inflammatory disease
• Prostatitis
• Acute pyelonephritis

Dosage

Children: Refer to the BNF for Children for specific dosing guidance.

Adults: 200–400 mg daily for 3 days for uncomplicated urinary-tract infections; for severe or complicated infections, the dose may be increased to 400 mg twice daily for 7–10 days. In cases of renal impairment, the dose should be adjusted based on creatinine clearance.

Mechanism of action

Ofloxacin acts by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes crucial for DNA replication and transcription. This inhibition prevents normal cell division, leading to cell death. Ofloxacin has a significantly higher affinity for bacterial DNA gyrase compared to mammalian enzymes, making it effective against infectious pathogens.

Pharmacodynamics

As a quinolone antibiotic, ofloxacin demonstrates bactericidal activity, meaning it kills bacteria rather than merely inhibiting their growth. Its mechanism is primarily through the disruption of DNA supercoiling, a vital process for bacterial cell division and viability. The drug's broad-spectrum activity allows it to target a wide variety of bacterial pathogens, enhancing its utility in clinical settings.

Pharmacokinetics

Ofloxacin is well-absorbed after oral administration, with a bioavailability of approximately 98%. It is primarily metabolized in the liver and excreted through the kidneys, necessitating caution in patients with hepatic or renal impairment. The elimination half-life is about 4 to 7 hours, which supports twice-daily dosing for effective therapeutic levels.

Contra-indications

• Hypersensitivity to ofloxacin or other quinolones
• History of tendon disorders related to fluoroquinolone use
• Severe hepatic impairment
• History of QT interval prolongation
• Concurrent use of drugs that prolong the QT interval

Adverse effects

• Nausea
• Diarrhea
• Headache
• Dizziness
• Tendonitis and tendon rupture
• QT interval prolongation
• Photosensitivity
• Rash
• Anaphylaxis

Interactions

• Antacids containing magnesium or aluminum (may reduce absorption)
• Cationic drugs (e.g., iron salts, sucralfate)
• Warfarin (may enhance anticoagulant effect)
• Drugs that prolong the QT interval (e.g., class IA and III antiarrhythmics)

Precautions

• Use with caution in patients with a history of seizures or CNS disorders
• Monitor for signs of tendon damage
• Assess renal function prior to dosing, especially in elderly patients
• Caution in patients with a history of myasthenia gravis

Pregnancy

Manufacturer advises use only if the benefit outweighs the risk, as systemic quinolones have been associated with risks during pregnancy.

Breast-feeding

Ofloxacin is excreted in breast milk; caution is advised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Protect from light.

Formulations

• 200 mg tablets
• 400 mg tablets
• Injectable solution (200 mg in 100 mL)
• Eye drops (0.3% solution)

Mechanism of action

The most widely accepted mechanism of NTZ is believed to be the disruption of the energy metabolism in anaerobic microbes by inhibition of the pyruvate: ferredoxin/flavodoxin oxidoreductase (PFOR) cycle. In parasitic-protozoa, Nitazoxanide also induces lesions in the cell membranes and depolarizes the mitochondrial membrane while inhibiting quinone oxidoreductase NQO1, nitroreductase-1 and protein disulphide isomerase enzymes. In addition, this drug also inhibits the glutathione-S-transferase (a major detoxifying enzyme) and modulates the Avr-14 gene, encoding for the alpha-type subunit of glutamate-gated chloride ion channel present in nematodes. Aside from its well understood non-competitive inhibition of the PFOR in anaerobic bacteria, NTZ also demonstrates various other antibacterial mechanisms. It inhibits pyruvate dehydrogenase in E Coli, disrupts the membrane potential and pH homeostasis in the Mycobacterium tuberculosis, suppresses the chaperone/usher (CU) pathway of the gram-negative bacteria, and stimulates host macrophage autophagy in tuberculosis patients. NTZ also suppresses viral replication by inhibiting the maturation of the viral hemagglutinin and the viral transcription factor immediate early 2 (IE2) as well as by activating the eukaryotic translation initiation factor 2α (an antiviral intracellular protein). Lastly, NTZ exhibits an inhibitory effect on tumor cell progression by altering drug detoxification (glutathione-S-transferase P1), unfolded protein response, autophagy, anti-cytokines activity, and c-Myc inhibition.

Pharmacodynamics

The general effect of this medication is the prevention of microbe activity through disruption of important energy pathways for survival and proliferation. Nitazoxanide exhibits antiprotozoal activity by interfering with the pyruvate ferredoxin/flavodoxin oxidoreductase dependent electron transfer reaction, an essential reaction need for anaerobic energy metabolism of various microorganisms. Sporozoites of Cryptosporidium parvum and trophozoites of Giardia lamblia are therefore inhibited, relieving symptoms of diahrrea. Interference with the PFOR enzyme-dependent electron transfer reaction may only be one of the many pathways by which nitazoxanide exhibits antiprotozoal activity.

Mechanism of action

Ofloxacin acts on DNA gyrase and toposiomerase IV, enzymes which, like human topoisomerase, prevents the excessive supercoiling of DNA during replication or transcription. By inhibiting their function, the drug thereby inhibits normal cell division. Quinolone(s) (QNs) is widely used in infection therapy due to its good antimicrobial characteristics. However, QNs-induced arthropathy of immature animals has led to restrictions on the therapeutic use of these antimicrobial agents. The exact mechanism(s) of QNs-induced chondrotoxicity remain unknown. In the present study, .../the authors/ investigated the possible mechanism of ofloxacin (one typical QNs)-induced injuries of chondrocytes. Juvenile rabbit joint chondrocytes cultured in alginate microspheres were incubated with ofloxacin at concentrations of 0, 2, 5, 10, 20, and 40 microg/mL for up to 96 hr. Concentration of 10 microg/mL ofloxacin induced apoptosis of chondrocyte with visible apoptotic signs, including degradation of poly(ADP-ribose) polymerase, caspase-3 activation, and DNA ladder formation. Furthermore, extracellular signal-regulated kinase 1/2 (phospho-ERK1/2) and growth factor receptor-bound protein 2 (Grb2) were significantly reduced, and similar changes were also observed in the beta(1)-integrin receptor as assessed by immunoblotting. However, the mRNA level of beta(1)-integrin obtained from reverse transcription-polymerase chain reaction remained unchanged. Results of beta(1)-integrin immunoprecipitation have also shown that beta(1)-integrin did not interact with activated intracellular signaling proteins. In addition, ofloxacin did not induce apoptosis and decrease beta(1)-integrin expression in chondrocytes supplemented with Mg(2+), and the ofloxacin-induced apoptosis was caspase-8-dependent, inhibition of which did not affect the expression mode of phospho-ERK1/2 and beta(1)-integrin. Our results demonstrate that ofloxacin affects beta(1)-integrin receptor functions and the ERK mitogen-activated protein kinase signaling pathway, causing caspase-8-dependent apoptosis after exposure of 48 hr. Quinolones are widely used in infection therapy due to their good antimicrobial characteristics. However, there potential joint chondrotoxicity on immature animals has stood in the way of the therapeutic application of these agents, the exact mechanism of which is still unclear. This study was undertaken to investigate the role of oxidative damage in ofloxacin (one typical quinolones)-induced arthropathy. Chondrocytes from juvenile rabbit joints were incubated with ofloxacin at concentrations of 0, 5, 10, 20, 40 and 80 ug/mL, respectively. The extent of oxidative damage was assessed by measuring the reactive oxygen species level, activities of antioxidant enzymes, and oxidative damage to some macromolecules. It was observed that ofloxacin induced a concentration-dependent increase in intracellular reactive oxygen species production, which may be an early mediator of ofloxacin cytotoxicity. Similarly, ofloxacin resulted in a significant lipid peroxidation, revealed by a concentration-dependent increase in the level of thiobarbituric acid reactive substances. At the same time, ofloxacin induced DNA damage in a concentration-dependent manner for 24 hr measured by comet assay, which may be a cause for overproduction of reactive oxygen species. Furthermore, antioxidant enzyme activities, such as glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD), were rapidly decreased after treatment with ofloxacin. In addition, SOD decline and reactive oxygen species production were strongly inhibited, and the loss in cell viability was partly abated by additional glutathione (GSH), N-acetylcysteine (NAC) and dithiothreitol (DTT). In conclusion, these results clearly demonstrated that ofloxacin could induce oxidative stress, lipid peroxidation and DNA oxidative damage to chondrocytes. Ofloxacin is a quinolone antimicrobial agent. The mechanism of action of ofloxacin and o

Pharmacodynamics

Ofloxacin is a quinolone/fluoroquinolone antibiotic. Ofloxacin is bactericidal and its mode of action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase, which allows the untwisting required to replicate one DNA double helix into two. Notably the drug has 100 times higher affinity for bacterial DNA gyrase than for mammalian. Ofloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria.