Chemically, nitazoxanide is the prototype member of the thiazolides, a class of drugs which are synthetic nitrothiazolyl-salicylamide derivatives with antiparasitic and antiviral activity.[4][6][8]Tizoxanide, an active metabolite of nitazoxanide in humans, is also an antiparasitic drug of the thiazolide class.[4][9]
Nitazoxanide tablets were approved as a generic medication in the United States in 2020.[10]
Nitazoxanide alone has shown preliminary evidence of efficacy in the treatment of chronic hepatitis B over a one-year course of therapy.[17] Nitazoxanide 500 mg twice daily resulted in a decrease in serum HBV DNA in all of 4 HBeAg-positive patients, with undetectable HBV DNA in 2 of 4 patients, loss of HBeAg in 3 patients, and loss of HBsAg in one patient. Seven of 8 HBeAg-negative patients treated with nitazoxanide 500 mg twice daily had undetectable HBV DNA and 2 had loss of HBsAg. Additionally, nitazoxanide monotherapy in one case and nitazoxanide plus adefovir in another case resulted in undetectable HBV DNA, loss of HBeAg and loss of HBsAg.[18] These preliminary studies showed a higher rate of HBsAg loss than any currently licensed therapy for chronic hepatitis B. The similar mechanism of action of interferon and nitazoxanide suggest that stand-alone nitazoxanide therapy or nitazoxanide in concert with nucleos(t)ide analogs have the potential to increase loss of HBsAg, which is the ultimate end-point of therapy. A formal phase 2 study is being planned for 2009.[19]
Chronic hepatitis C
Romark initially decided to focus on the possibility of treating chronic hepatitis C with nitazoxanide.[20] The drug garnered interest from the hepatology community after three phase II clinical trials involving the treatment of hepatitis C with nitazoxanide produced positive results for treatment efficacy and similar tolerability to placebo without any signs of toxicity.[20] A meta-analysis from 2014 concluded that the previous held trials were of low-quality and withheld with a risk of bias. The authors concluded that more randomized trials with low risk of bias are needed to determine if Nitazoxanide can be used as an effective treatment for chronic hepatitis C patients.[21]
The side effects of nitazoxanide do not significantly differ from a placebo treatment for giardiasis;[1] these symptoms include stomach pain, headache, upset stomach, vomiting, discolored urine, excessive urinating, skin rash, itching, fever, flu syndrome, and others.[1][22] Nitazoxanide does not appear to cause any significant adverse effects when taken by healthy adults.[1][2]
Overdose
Information on nitazoxanide overdose is limited. Oral doses of 4 grams in healthy adults do not appear to cause any significant adverse effects.[1][2] In various animals, the oral LD50 is higher than 10 g/kg.[1]
The anti-protozoal activity of nitazoxanide is believed to be due to interference with the pyruvate:ferredoxin oxidoreductase (PFOR) enzyme-dependent electron-transfer reaction that is essential to anaerobic energy metabolism.[1][8] PFOR inhibition may also contribute to its activity against anaerobic bacteria.[23]
It has also been shown to have activity against influenza A virus in vitro.[24] The mechanism appears to be by selectively blocking the maturation of the viral hemagglutinin at a stage preceding resistance to endoglycosidase H digestion. This impairs hemagglutinin intracellular trafficking and insertion of the protein into the host plasma membrane.[citation needed]
Nitazoxanide modulates a variety of other pathways in vitro, including glutathione-S-transferase and glutamate-gated chloride ion channels in nematodes, respiration and other pathways in bacteria and cancer cells, and viral and host transcriptional factors.[23]
Pharmacokinetics
Following oral administration, nitazoxanide is rapidly hydrolyzed to the pharmacologically active metabolite, tizoxanide, which is 99% protein bound.[1][9] Tizoxanide is then glucuronide conjugated into the active metabolite, tizoxanide glucuronide.[1] Peak plasma concentrations of the metabolites tizoxanide and tizoxanide glucuronide are observed 1–4 hours after oral administration of nitazoxanide, whereas nitazoxanide itself is not detected in blood plasma.[1]
Roughly 2⁄3 of an oral dose of nitazoxanide is excreted as its metabolites in feces, while the remainder of the dose excreted in urine.[1] Tizoxanide is excreted in the urine, bile and feces.[1] Tizoxanide glucuronide is excreted in urine and bile.[1]
Chemistry
This section needs expansion. You can help by adding to it. (January 2016)
Acetic acid [2-[(5-nitro-2-thiazolyl)amino]-oxomethyl]phenyl ester is a carboxylic ester and a member of benzamides. It is functionally related to a salicylamide.
Nitazoxanide[25] is the prototype member of the thiazolides, which is a drug class of structurally-related broad-spectrum antiparasitic compounds. Nitazoxanide belongs to the class of drugs known as thiazolides. It is a broad-spectrum anti-infective drug that significantly modulates the survival, growth, and proliferation of a range of extracellular and intracellular protozoa, helminths, anaerobic and microaerophilic bacteria, in addition to viruses.[4] Nitazoxanide is a light yellow crystalline powder. It is poorly soluble in ethanol and practically insoluble in water.
The molecular formula of Nitazoxanide is C12H9N3O5S and its molecular weight is 307.28 g/mol2.
Tizoxanide, an active metabolite of nitazoxanide in humans, is also an antiparasitic drug of the thiazolide class.
Nitazoxanide was originally discovered in the 1980s by Jean-François Rossignol at the Pasteur Institute. Initial studies demonstrated activity versus tapeworms. In vitro studies demonstrated much broader activity. Dr. Rossignol co-founded Romark Laboratories, with the goal of bringing nitazoxanide to market as an anti-parasitic drug. Initial studies in the USA were conducted in collaboration with Unimed Pharmaceuticals, Inc. (Marietta, GA) and focused on development of the drug for treatment of cryptosporidiosis in AIDS. Controlled trials began shortly after the advent of effective anti-retroviral therapies. The trials were abandoned due to poor enrollment and the FDA rejected an application based on uncontrolled studies.[citation needed]
Subsequently, Romark launched a series of controlled trials. A placebo-controlled study of nitazoxanide in cryptosporidiosis demonstrated significant clinical improvement in adults and children with mild illness. Among malnourished children in Zambia with chronic cryptosporidiosis, a three-day course of therapy led to clinical and parasitologic improvement and improved survival. In Zambia and in a study conducted in Mexico, nitazoxanide was not successful in the treatment of cryptosporidiosis in advanced infection with human immunodeficiency virus at the doses used. However, it was effective in patients with higher CD4 counts. In treatment of giardiasis, nitazoxanide was superior to placebo and comparable to metronidazole. Nitazoxanide was successful in the treatment of metronidazole-resistant giardiasis. Studies have suggested efficacy in the treatment of cyclosporiasis, isosporiasis, and amebiasis.[29] Recent studies have also found it to be effective against beef tapeworm (Taenia saginata).[18]
Pharmaceutical products
Dosage forms
Nitazoxanide is currently available in two oral dosage forms: a tablet (500 mg) and an oral suspension (100 mg per 5 ml when reconstituted).[1]
An extended release tablet (675 mg) has been used in clinical trials for chronic hepatitis C; however, this form is not currently marketed or available for prescription.[20]
Brand names
Nitazoxanide is sold under the brand names Adonid, Alinia,[30] Allpar, Annita, Celectan, Colufase, Daxon, Dexidex, Diatazox, Kidonax, Mitafar, Nanazoxid,[31] Parazoxanide, Netazox, Niazid, Nitamax, Nitax, Nitaxide, Nitaz, Nizonide, NT-TOX, Pacovanton, Paramix, Toza, and Zox.
^ abcdeStockis A, Allemon AM, De Bruyn S, Gengler C (May 2002). "Nitazoxanide pharmacokinetics and tolerability in man using single ascending oral doses". International Journal of Clinical Pharmacology and Therapeutics. 40 (5): 213–220. doi:10.5414/cpp40213. PMID12051573.
^"Nitazoxanide". PubChem. National Center for Biotechnology Information, U.S. National Library of Medicine. Retrieved 3 January 2016.
^ abcdeDi Santo N, Ehrisman J (September 2013). "Research perspective: potential role of nitazoxanide in ovarian cancer treatment. Old drug, new purpose?". Cancers. 5 (3): 1163–1176. doi:10.3390/cancers5031163. PMC3795384. PMID24202339. Nitazoxanide [NTZ: 2-acetyloxy-N-(5-nitro-2-thiazolyl)benzamide] is a thiazolide antiparasitic agent with excellent activity against a wide variety of protozoa and helminths. ... Nitazoxanide (NTZ) is a main compound of a class of broad-spectrum anti-parasitic compounds named thiazolides. It is composed of a nitrothiazole-ring and a salicylic acid moiety which are linked together by an amide bond ... NTZ is generally well tolerated, and no significant adverse events have been noted in human trials [13]. ... In vitro, NTZ and tizoxanide function against a wide range of organisms, including the protozoal species Blastocystis hominis, C. parvum, Entamoeba histolytica, G. lamblia and Trichomonas vaginalis [13]
^ abcdefRossignol JF (October 2014). "Nitazoxanide: a first-in-class broad-spectrum antiviral agent". Antiviral Research. 110: 94–103. doi:10.1016/j.antiviral.2014.07.014. PMC7113776. PMID25108173. Originally developed and commercialized as an antiprotozoal agent, nitazoxanide was later identified as a first-in-class broad-spectrum antiviral drug and has been repurposed for the treatment of influenza. ... From a chemical perspective, nitazoxanide is the scaffold for a new class of drugs called thiazolides. These small-molecule drugs target host-regulated processes involved in viral replication. ... A new dosage formulation of nitazoxanide is presently undergoing global Phase 3 clinical development for the treatment of influenza. Nitazoxanide inhibits a broad range of influenza A and B viruses including influenza A(pH1N1) and the avian A(H7N9) as well as viruses that are resistant to neuraminidase inhibitors. ... Nitazoxanide also inhibits the replication of a broad range of other RNA and DNA viruses including respiratory syncytial virus, parainfluenza, coronavirus, rotavirus, norovirus, hepatitis B, hepatitis C, dengue, yellow fever, Japanese encephalitis virus and human immunodeficiency virus in cell culture assays. Clinical trials have indicated a potential role for thiazolides in treating rotavirus and norovirus gastroenteritis and chronic hepatitis B and chronic hepatitis C. Ongoing and future clinical development is focused on viral respiratory infections, viral gastroenteritis and emerging infections such as dengue fever.
^ abAnderson VR, Curran MP (2007). "Nitazoxanide: a review of its use in the treatment of gastrointestinal infections". Drugs. 67 (13): 1947–1967. doi:10.2165/00003495-200767130-00015. PMID17722965. S2CID260860340. Nitazoxanide is effective in the treatment of protozoal and helminthic infections ... Nitazoxanide is a first-line choice for the treatment of illness caused by C. parvum or G. lamblia infection in immunocompetent adults and children, and is an option to be considered in the treatment of illnesses caused by other protozoa and/or helminths.
^Roberts T, Stark D, Harkness J, Ellis J (May 2014). "Update on the pathogenic potential and treatment options for Blastocystis sp". Gut Pathogens. 6: 17. doi:10.1186/1757-4749-6-17. PMC4039988. PMID24883113. Blastocystis is one of the most common intestinal protists of humans. ... A recent study showed that 100% of people from low socio-economic villages in Senegal were infected with Blastocystis sp. suggesting that transmission was increased due to poor hygiene sanitation, close contact with domestic animals and livestock, and water supply directly from well and river [10]. ...
^Muñoz P, Valerio M, Eworo A, Bouza E (December 2011). "Parasitic infections in solid-organ transplant recipients". Current Opinion in Organ Transplantation. 16 (6): 565–575. doi:10.1097/MOT.0b013e32834cdbb0. PMID22027588. S2CID23861504. Nitazoxanide: intestinal amoebiasis: 500 mg po bid x 3 days
^Hagel I, Giusti T (October 2010). "Ascaris lumbricoides: an overview of therapeutic targets". Infectious Disorders Drug Targets. 10 (5): 349–367. doi:10.2174/187152610793180876. PMID20701574. S2CID15403331. new anthelmintic alternatives such as tribendimidine and Nitazoxanide have proved to be safe and effective against A. lumbricoides and other soil-transmitted helminthiases in human trials.
^Shoff WH (5 October 2015). Chandrasekar PH, Talavera F, King JW (eds.). "Cyclospora Medication". Medscape. WebMD. Retrieved 11 January 2016. Nitazoxanide, a 5-nitrothiazole derivative with broad-spectrum activity against helminths and protozoans, has been shown to be effective against C cayetanensis, with an efficacy 87% by the third dose (first, 71%; second 75%). Three percent of patients had minor side effects.
^World Journal of Gastroenterology 2009 April 21, Emmet B Keeffe MD, Professor, Jean-François Rossignol The Romark Institute for Medical Research, Tampa
^Li TC, Chan MC, Lee N (September 2015). "Clinical Implications of Antiviral Resistance in Influenza". Viruses. 7 (9): 4929–4944. doi:10.3390/v7092850. PMC4584294. PMID26389935. Oral nitazoxanide is an available, approved antiparasitic agent (e.g., against cryptosporidium, giardia) with established safety profiles. Recently, it has been shown (together with its active metabolite tizoxanide) to possess anti-influenza activity by blocking haemagglutinin maturation/trafficking, and acting as an interferon-inducer [97]. ... A large, multicenter, Phase 3 randomized-controlled trial comparing nitazoxanide, oseltamivir, and their combination in uncomplicated influenza is currently underway (NCT01610245). Figure 1: Molecular targets and potential antiviral treatments against influenza virus infection
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