Nitazoxanide

Nitazoxanide belongs to the class of drugs known as thiazolides. Nitazoxanide (NTZ) is a broad-spectrum anti-infective drug that markedly modulates the survival, growth, and proliferation of a range of extracellular and intracellular protozoa, helminths, anaerobic and microaerophilic bacteria, in addition to viruses. This drug is effective in the treatment of gastrointestinal infections including Cryptosporidium parvum or Giardia lamblia in healthy subjects. It is generally well tolerated. Nitazoxanide is a first-line, standard treatment for illness caused by C. parvum or G. lamblia infection in healthy (not immunosuppressed) adults and children and may also be considered in the treatment of illnesses caused by other protozoa or helminths . Recently, this drug has been studied as a broad-spectrum antiviral agent due to its ability to inhibit the replication of several RNA and DNA viruses .

Nitazoxanide is a thiazolide anti-infective used to treat infections by protozoa, helminths, anaerobic bacteria, microaerophilic bacteria, and viruses.

For the treatment of diarrhea in adults and children caused by the protozoa Giardia lamblia, and for the treatment of diarrhea in children caused by the protozoan, Cryptosporidium parvum .

Nitazoxanide has not been shown to be superior to placebo medication for the management of diarrhea caused by Cryptosporidium parvum in patients with HIV/immunodeficiency .

• Ascariasis
• Cestode infections
• Clostridium difficile infection recurrence
• Cryptosporidiosis infection
• Diarrhea caused by Cryptosporidium parvum
• Diarrhea caused by Giardia lamblia
• Giardiasis
• Trichuriasis

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 .

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 .

The relative bioavailability of the suspension compared to the tablet was 70%. When administered with food the AUC and C_max increased by two-fold and 50%, respectively, for the tablet and 45 to 50% and ≤ 10%, respectively, for the oral suspension .

Very High (greater than 99%), bound to proteins in the plasma .

Tizoxanide is excreted in the urine, bile and feces, and tizoxanide glucuronide is excreted in urine and bile. Approximately 2/3 of the oral dose of nitazoxanide is excreted in the faeces and 1/3 in the urine .

7.3h

Nitazoxanide is cleared in the urine and feces. The metabolite, tizoxanide, is also found in the urine, plasma, and breastmilk . The drug is not found unchanged in the urine .

Data on nitazoxanide overdosage is not available . In studies in rodents and dogs, the oral LD50 was higher than 10,000 mg/kg. One-time oral doses of up to 4000 mg nitazoxanide have been given to healthy adult volunteers without severe adverse effects. Gastric lavage may be appropriate soon after oral administration if overdose occurs. Supportive and symptomatic treatment should also be administered .

According to previous studies , less than 1% of the patients age 12 years and older participating in clinical trials with NTZ suffered from the following adverse effects: Systemic: asthenia, fever, pain, allergic reaction, pelvic pain, back pain, chills, fever, flu-like syndrome. Central Nervous System: dizziness, somnolence, insomnia, tremor, hypesthesia. Gastrointestinal System: vomiting, dyspepsia, anorexia, flatulence, constipation, dry mouth, thirst. Urogenital System: discolored urine, dysuria, amenorrhea, metrorrhagia, kidney pain, edema labia. Metabolic & Nutrition: increased SGPT. Hemic & Lymphatic Systems: anemia, leukocytosis. Skin: rash, pruritus. Special Senses: eye discoloration, ear ache. Respiratory System: epistaxis, lung disease, pharyngitis. Cardiovascular System: tachycardia, syncope, hypertension. Muscular System: myalgia, leg cramps, spontaneous bone fracture.

• Take with food. Food improves oral bioavailability.