Nitazoxanide in treatment of Helicobacter pylori: a clinical and in vitro study

Green "turn-off" luminescent nanosensors for the sensitive determination of desperately fluorescent antibacterial antiviral agent and its metabolite in various matrices

Nitazoxanide (NTX) is an antimicrobial drug that was used for the treatment of various protozoa. However, during the coronavirus pandemic, NTX has been redirected for the treatment of such virus that primarily infect the respiratory tract system. NTX is now used as a broad-spectrum antiviral agent. In this study, a highly sensitive and green spectrofluorometric method was developed to detect NTX in various dosage forms and its metabolite, tizoxanide (TX), in human plasma samples using nitrogen and sulfur co-doped carbon quantum dots nanosensors (C-dots). A simple and eco-friendly hydrothermal method was used to synthetize water soluble C-dots from citric acid and l-cysteine. After excitation at 345 nm, the luminescence intensity was measured at 416 nm. Quenching of C-dots luminescence occurred upon the addition of NTX and was proportional to NTX concentration. Assessment of the quenching mechanism was performed to prove that inner filter effect is the underlying molecular mechanism of NTX quenching accomplished. After optimizing all experimental parameters, the analytical procedure was evaluated and validated using the ICH guidelines. The method linearity, detection and quantification limits of NTX were 15 × 10-3-15.00 µg/mL, 56.00 × 10-4 and 15 × 10-3 µg/mL, respectively. The proposed method was applied for the determination of NTX in its commercial pharmaceutical products; Nanazoxid® oral suspension and tablets. The obtained % recovery, relative standard deviation and % relative error were satisfactory. Comparison with other reported spectrofluorimetric methods revealed the superior sensitivity of the proposed method. Such high sensitivity permitted the selective determination of TX, the main metabolite of NTX, in human plasma samples making this study the first spectrofluorimetric method in literature that determine TX in human plasma samples. Moreover, the method greenness was assessed using both Eco-Scale and AGREE approaches to prove the superiority of the proposed method greenness over other previously published spectrofluorimetric methods for the analysis of NTX and its metabolite, TX, in various dosage forms and in human plasma samples.

Molecular Mechanisms of Antibiotic Resistance and Novel Treatment Strategies for Helicobacter pylori Infections

Helicobacter pylori infects approximately 50% of the world's population and is considered the major etiological agent of severe gastric diseases, such as peptic ulcers and gastric carcinoma. Increasing resistance to standard antibiotics has now led to an ever-decreasing efficacy of eradication therapies and the development of novel and improved regimens for treatment is urgently required. Substantial progress has been made over the past few years in the identification of molecular mechanisms which are conducive to resistant phenotypes as well as for efficient strategies to counteract strain resistance and to avoid the use of ineffective antibiotics. These involve molecular testing methods, improved salvage therapies, and the discovery of novel and potent antimicrobial compounds. High rates of prevalence and gastric cancer are currently observed in Asian countries, including Japan, China, Korea, and Taiwan, where concomitantly intensive research efforts were initiated to explore advanced eradication regimens aimed at reducing the risk of gastric cancer. In this review, we present an overview of the known molecular mechanisms of antibiotic resistance and discuss recent intervention strategies for H. pylori diseases, with a view of the research progress in Asian countries.

Efficacy and safety of nitazoxanide in treating SARS-CoV-2 infection: a systematic review and meta-analysis of blinded, placebo-controlled, randomized clinical trials

Purpose

Nitazoxanide is a broad-spectrum antiparasitic that has been tested for COVID-19 due to its anti-inflammatory effects and in vitro antiviral activity. This study synthesized the best evidence on the efficacy and safety of nitazoxanide in COVID-19.

Methods

Searches for studies were performed in peer-reviewed and grey-literature from January 1, 2020 to May 23, 2022. The following elements were used to define eligibility criteria: (1) Population: individuals with COVID-19; (2) Intervention: nitazoxanide; (3) Comparison: placebo; (4) Outcomes: primary outcome was death, and secondary outcomes were viral load, positive RT-PCR status, serum biomarkers of inflammation, composite measure of disease progression (ICU admission or invasive mechanical ventilation), and any adverse events; (5) Study type: blinded, placebo-controlled, randomized clinical trials (RCTs). Treatment effects were reported as relative risk (RR) for dichotomous variables and standardized mean difference (SMD) for continuous variables with 95% confidence intervals (CI).

Results

Five blinded, placebo-controlled RCTs were included and enrolled individuals with mild or moderate SARS-CoV-2 infection. We found no difference between nitazoxanide and placebo in reducing viral load (SMD =  − 0.16; 95% CI − 0.38 to 0.05) and the frequency of positive RTP-PCR results (RR = 0.92; 95% CI 0.81 to 1.06). In addition, there was no decreased risk for disease progression (RR = 0.63; 95% CI 0.38 to 1.04) and death (RR = 0.81; 95% CI 0.36 to 1.78) among patients receiving nitazoxanide. Patients with COVID-19 treated with nitazoxanide had decreased levels of white blood cells (SMD =  − 0.15; 95% − 0.29 to − 0.02), lactate dehydrogenase (LDH) (SMD − 0.32; 95% − 0.52 to − 0.13), and D-dimer (SMD − 0.49; 95% CI − 0.68 to − 0.31) compared to placebo, but the magnitude of effect was considered small to moderate.

Conclusion

This systematic review showed no evidence of clinical benefits of the use of nitazoxanide to treat patients with mild or moderate COVID-19. In addition, we found a reduction in WBC, LDH, and D-dimer levels among nitazoxanide-treated patients, but the effect size was considered small to moderate.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-022-03380-5.

Identification of Antimotilins, Novel Inhibitors of Helicobacter pylori Flagellar Motility That Inhibit Stomach Colonization in a Mouse Model

New treatment options against the widespread cancerogenic gastric pathogen Helicobacter pylori are urgently needed. We describe a novel screening procedure for inhibitors of H. pylori flagellar biosynthesis. The assay is based on a flaA flagellin gene-luciferase reporter fusion in H. pylori and was amenable to multi-well screening formats with an excellent Z factor. We screened various compound libraries to identify virulence blockers ("antimotilins") that inhibit H. pylori motility or the flagellar type III secretion apparatus. We identified compounds that either inhibit both motility and the bacterial viability, or the flagellar system only, without negatively affecting bacterial growth. Novel anti-virulence compounds which suppressed flagellar biosynthesis in H. pylori were active on pure H. pylori cultures in vitro and partially suppressed motility directly, reduced flagellin transcript and flagellin protein amounts. We performed a proof-of-principle treatment study in a mouse model of chronic H. pylori infection and demonstrated a significant effect on H. pylori colonization for one antimotilin termed Active2 even as a monotherapy. The diversity of the intestinal microbiota was not significantly affected by Active2. In conclusion, the novel antimotilins active against motility and flagellar assembly bear promise to complement commonly used antibiotic-based combination therapies for treating and eradicating H. pylori infections. IMPORTANCE Helicobacter pylori is one of the most prevalent bacterial pathogens, inflicting hundreds of thousands of peptic ulcers and gastric cancers to patients every year. Antibacterial treatment of H. pylori is complicated due to the need of combining multiple antibiotics, entailing serious side effects and increasing selection for antibiotic resistance. Here, we aimed to explore novel nonantibiotic approaches to H. pylori treatment. We selected an antimotility approach since flagellar motility is essential for H. pylori colonization. We developed a screening system for inhibitors of H. pylori motility and flagellar assembly, and identified numerous novel antibacterial and anti-motility compounds (antimotilins). Selected compounds were further characterized, and one was evaluated in a preclinical therapy study in mice. The antimotilin compound showed a good efficacy to reduce bacterial colonization in the model, such that the antimotilin approach bears promise to be further developed into a therapy against H. pylori infection in humans.

Novel phenolic antimicrobials enhanced activity of iminodiacetate prodrugs against biofilm and planktonic bacteria

Prodrugs are pharmacologically attenuated derivatives of drugs that undergo bioconversion into the active compound once reaching the targeted site, thereby maximizing their efficiency. This strategy has been implemented in pharmaceuticals to overcome obstacles related to absorption, distribution, and metabolism, as well as with intracellular dyes to ensure concentration within cells. In this study, we provide the first examples of a prodrug strategy that can be applied to simple phenolic antimicrobials to increase their potency against mature biofilms. The addition of (acetoxy)methyl iminodiacetate groups increases the otherwise modest potency of simple phenols. Biofilm-forming bacteria exhibit a heightened tolerance toward antimicrobial agents, thereby accentuating the need for new antibiotics as well as those, which incorporate novel delivery strategies to enhance activity toward biofilms.

Safety and Efficacy of Nitazoxanide-Based Regimen for the Eradication of Helicobacter pylori Infection: A Systematic Review and Meta-Analysis

Background

Helicobacter pylori (HP) is the most common cause of gastritis worldwide. Clarithromycin-based triple therapy or bismuth-based quadruple therapy is usually considered the first-line treatment, however with around 30% failure rate for both regimens. Drug resistance of clarithromycin and metronidazole is a growing concern in some parts of the world. Therefore, there is a need for effective eradication regimen for HP. Nitazoxanide, a bactericidal thiazolide antibiotic, has been shown to be effective in HP infection. We conducted a systematic review and meta-analysis to evaluate the efficacy of nitazoxanide-based regimen for the eradication of HP.

Methods

We have searched PubMed, Embase, Ovid Medline and Cochrane library database from inception to December 9, 2020 to identify studies that utilized nitazoxanide in the treatment regimen for HP eradication. Our primary outcome was pooled eradication rate of HP.

Results

Thirteen studies including 1,028 patients met our inclusion criteria and were analyzed in a meta-analysis. HP eradication was successful in 867 patients with a pooled eradication rate of 86% (95% confidence interval (CI): 79-90%) with 84% heterogeneity. A subgroup analysis that included 230 patients who failed other prior eradication regimens revealed a pooled eradication rate of 85% (95% CI: 69-94%) without heterogeneity. In a subgroup analysis, highest eradication rates were achieved with levofloxacin, doxycycline, nitazoxanide and proton pump inhibitor with a pooled eradication rate of 92% (88-95%).

Conclusion

Nitazoxanide-based regimen is safe and effective in the eradication of HP infection. It is also successful as a salvage therapy in patients who have failed prior treatments.

Treatment of Helicobacter pylori with nitazoxanide-containing regimens: a systematic review

Background: Helicobacter pylori is one of the most common chronic infections and is a leading cause of gastric cancer. There are currently several short-course treatment options available for the treatment of H. pylori. However, there has been a significant increase in global resistance patterns for H. pylori and there is a need for alternative treatment regimens. Nitazoxanide (NTZ) is an anti-protozoal agent that has been evaluated within several studies for the treatment of H. pylori. The objective of this review is to evaluate the efficacy and safety of NTZ-based treatments for a H. pylori infection.Methods: Pubmed (1946-August 2019) and Embase (1947-August 2019) were queried using the following search terms: Helicobacter, Helicobacter infection, Helicobacter pylori, nitazoxanide, tizoxanide, thiazoles, thiazole derivative and NTZ. Appropriate studies were evaluated with varying treatment regimens and cure rates.Results: Ten studies that utilized a NTZ-based treatment for H. pylori were identified from the literature search. Eight of the ten studies demonstrated a cure rate of greater than 80% in at least one NTZ-based treatment arm. Gastrointestinal side effects were the most commonly reported adverse drug reaction in the studies.Conclusions: Nitazoxanide-based treatments appear to be an effective treatment for H. pylori. While the ideal NTZ combination therapy is uncertain, a combination with a proton-pump inhibitor and one to two antibiotics has demonstrated the highest rates of H. pylori eradication. Nitazoxanide-based treatments are well-tolerated and minimal discontinuation due to side effects were reported in the studies.

Thiazolides promote G1 cell cycle arrest in colorectal cancer cells by targeting the mitochondrial respiratory chain

Systemic toxicity and tumor cell resistance still limit the efficacy of chemotherapy in colorectal cancer. Therefore, alternative treatments are desperately needed. The thiazolide Nitazoxanide (NTZ) is an FDA-approved drug for the treatment of parasite-mediated infectious diarrhea with a favorable safety profile. Interestingly, NTZ and the thiazolide RM4819-its bromo-derivative lacking antibiotic activity-are also promising candidates for cancer treatment. Yet the exact anticancer mechanism(s) of these compounds still remains unclear. In this study, we systematically investigated RM4819 and NTZ in 2D and 3D colorectal cancer culture systems. Both compounds strongly inhibited proliferation of colon carcinoma cell lines by promoting G1 phase cell cycle arrest. Thiazolide-induced cell cycle arrest was independent of the p53/p21 axis, but was mediated by inhibition of protein translation via the mTOR/c-Myc/p27 pathway, likely caused by inhibition of mitochondrial respiration. While both thiazolides demonstrated mitochondrial uncoupling activity, only RM4819 inhibited the mitochondrial respiratory chain complex III. Interestingly, thiazolides also potently inhibited the growth of murine colonic tumoroids in a comparable manner with cisplatin, while in contrast to cisplatin thiazolides did not affect the growth of primary intestinal organoids. Thus, thiazolides appear to have a tumor-selective antiproliferative activity, which offers new perspectives in the treatment of colorectal cancer.

Next-Generation Phenotypic Screening in Early Drug Discovery for Infectious Diseases

Cell-based phenotypic screening has proven to be valuable, notably in recapitulating relevant biological conditions, for example, the host cell/pathogen niche. However, the corresponding methodological complexity is not readily compatible with high-throughput pipelines, and fails to inform either molecular target or mechanism of action, which frustrates conventional drug-discovery roadmaps. We review the state-of-the-art and emerging technologies that suggest new strategies for harnessing value from the complexity of phenotypic screening and augmenting powerful utility for translational drug discovery. Advances in cellular, molecular, and bioinformatics technologies are converging at a cutting edge where the complexity of phenotypic screening may no longer be considered a hinderance but rather a catalyst to chemotherapeutic discovery for infectious diseases.

Randomized controlled study of a novel triple nitazoxanide (NTZ)-containing therapeutic regimen versus the traditional regimen for eradication of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori infection has become more and more resistant to conventional first-line treatment regimens. So, there is a considerable interest in evaluating new antibiotic combinations and regimens. Nitazoxanide is an anti-infective drug with demonstrated activity against protozoa and anaerobic bacteria including H. pylori. This work is designed to evaluate the efficacy and safety of a unique triple nitazoxanide-containing regimen as a treatment regimen in Egyptian patients with H. pylori infection.

METHODS

Two hundred and 24 patients with upper gastrointestinal tract (GIT) dyspeptic symptoms in whom H. pylori -induced GIT disease was confirmed were included in the study. They have been randomized to receive either nitazoxanide 500 mg b.i.d., clarithromycin 500 mg b.i.d., and omeprazole 40 mg twice daily for 14 days or metronidazole 500 mg b.i.d., clarithromycin 500 mg b.i.d., and omeprazole 40  mg twice daily for 14 days. Laboratory evaluation for H. pylori antigen within the stool was performed 6 weeks after cessation of H. pylori treatment regimens to assess the response.

RESULTS

The response to treatment was significantly higher in group 1 of nitazoxanide treatment regimen than group 2 of traditional treatment regimen. One hundred and six cases (94.6%) of 112 patients who completed the study in group 1 showed complete cure, while only 63 cases (60.6%) of 104 patients who completed the study in group 2 showed the same response according to per-protocol (PP) analysis (P<.001). The regimen was well tolerated by all the patients enrolled in the study.

CONCLUSION

Nitazoxanide-containing triple therapy is a promising therapy for the first-line eradication of H. pylori. (ClinicalTrials.gov Identifier: NCT02422706).

Sensitivity to nitazoxanide among metronidazole resistant Helicobacter pylori strains in patients with gastritis

BACKGROUND

In this study, the efficacy of nitazoxanide in the treatment of Helicobacter pylori isolates, which were resistant to metronidazole, was examined.

METHODS

One hundred twenty two patients who underwent endoscopy examinations at Kasra and Laleh hospitals in Tehran from November 2014 to July 2015 were enrolled. Helicobacter pylori strains were isolated from the patients' endoscopy biopsies by bacteriological culture. Those bacterial isolates resistant to metronidazole were examined for susceptibility to nitazoxanide. Serial agar dilution method was utilized to determine the minimum inhibitory concentrations for the antibiotics.

RESULTS

From 122 gastric biopsy specimens, 55 H. pylori isolates were recovered (45%); of which, 40 (72.7%) were resistant to metronidazole. Comparing the MIC values of nitazoxanide with metronidazole revealed significant differences (p<0.05). The MIC50 and MIC90 values for nitazoxanide and metronidazole were 8 and ≥8μg/ml, and 32 and 64μg/ml, respectively.

CONCLUSION

The high levels of metronidazole resistance suggest that this medication may not be beneficial for first-line therapy in Iran. However, considering the relative effectiveness of nitazoxanide, it may be considered a suitable alternative for patients in Iran.

A 2-week Nitazoxanide-based quadruple treatment as a rescue therapy for Helicobacter pylori eradication: A single center experience

As there are increasing reports of fluoroquinolone resistance on use as a first- or second-line treatment for Helicobacter pylori (H pylori), we aimed at evaluation of the efficacy and safety of nitazoxanide-based regimen as a rescue regimen in Egyptian patients whose previous traditional treatment for H pylori infection failed.In total, 100 patients from the outpatient clinic of the Tropical medicine department, Tanta University hospital in whom the standard triple therapy (clarithromycin-based triple therapy) failed were enrolled in the study. Nitazoxanide (500 mg bid), levofloxacin (500 mg once daily), omeprazole (40 mg bid), and doxycyclin (100 mg twice daily) were prescribed for 14 days. Eradication was confirmed by stool antigen for H pylori 6 weeks after the end of treatment. Among the patients enrolled in the study, 44% of patients were men and the mean age for the participants in the study was 46.41 ± 8.05, 13% of patients were smokers, and 4% of patients had a previous history of upper gastro-intestinal bleeding. A total of 94 patients (94%) completed the study with excellent compliance. Only 1 patient (1%) discontinued treatment due to intolerable side effects and 5 patients (5%) did not achieve good compliance or were lost during follow up. However, 83 patients had successful eradication of H pylori with total eradication rates 83% (95 % CI 75.7-90.3%) and 88.30% (95 % CI 81.8-94.8%) according to an intention-to-treat and per-protocol analysis, respectively. Adverse events were reported in 21% of patients: abdominal pain (6%), nausea (9%) and constipation (12%), (2%) headache, and (1%) dizziness. A 2-week nitazoxanide-based regimen is an effective and safe rescue therapy in Egyptian patients whose previous standard triple therapy has failed.

Preclinical studies of amixicile, a systemic therapeutic developed for treatment of Clostridium difficile infections that also shows efficacy against Helicobacter pylori

Amixicile shows efficacy in the treatment of Clostridium difficile infections (CDI) in a mouse model, with no recurrence of CDI. Since amixicile selectively inhibits the action of a B vitamin (thiamine pyrophosphate) cofactor of pyruvate:ferredoxin oxidoreductase (PFOR), it may both escape mutation-based drug resistance and spare beneficial probiotic gut bacteria that do not express this enzyme. Amixicile is a water-soluble derivative of nitazoxanide (NTZ), an antiparasitic therapeutic that also shows efficacy against CDI in humans. In comparative studies, amixicile showed no toxicity to hepatocytes at 200 μM (NTZ was toxic above 10 μM); was not metabolized by human, dog, or rat liver microsomes; showed equivalence or superiority to NTZ in cytochrome P450 assays; and did not activate efflux pumps (breast cancer resistance protein, P glycoprotein). A maximum dose (300 mg/kg) of amixicile given by the oral or intraperitoneal route was well tolerated by mice and rats. Plasma exposure (rats) based on the area under the plasma concentration-time curve was 79.3 h · μg/ml (30 mg/kg dose) to 328 h · μg/ml (100 mg/kg dose), the maximum concentration of the drug in serum was 20 μg/ml, the time to the maximum concentration of the drug in serum was 0.5 to 1 h, and the half-life was 5.6 h. Amixicile did not concentrate in mouse feces or adversely affect gut populations of Bacteroides species, Firmicutes, segmented filamentous bacteria, or Lactobacillus species. Systemic bioavailability was demonstrated through eradication of Helicobacter pylori in a mouse infection model. In summary, the efficacy of amixicile in treating CDI and other infections, together with low toxicity, an absence of mutation-based drug resistance, and excellent drug metabolism and pharmacokinetic metrics, suggests a potential for broad application in the treatment of infections caused by PFOR-expressing microbial pathogens in addition to CDI.

A c-Myc activation sensor-based high-throughput drug screening identifies an antineoplastic effect of nitazoxanide

Deregulation of c-Myc plays a central role in the tumorigenesis of many human cancers. Yet, the development of drugs regulating c-Myc activity has been challenging. To facilitate the identification of c-Myc inhibitors, we developed a molecular imaging sensor-based high-throughput screening (HTS) system. This system uses a cell-based assay to detect c-Myc activation in a HTS format, which is established from a pure clone of a stable breast cancer cell line that constitutively expresses a c-Myc activation sensor. Optimization of the assay performance in the HTS format resulted in uniform and robust signals at the baseline. Using this system, we conducted a quantitative HTS against approximately 5,000 existing bioactive compounds from five different libraries. Thirty-nine potential hits were identified, including currently known c-Myc inhibitors. There are a few among the top potent hits that are not known for anti-c-Myc activity. One of these hits is nitazoxanide, a thiazolide for treating human protozoal infections. Validation of nitazoxanide in different cancer cell lines revealed a high potency for c-Myc inhibition with IC50 ranging between 10 and 500 nmol/L. Oral administration of nitazoxanide in breast cancer xenograft mouse models significantly suppressed tumor growth by inhibition of c-Myc and induction of apoptosis. These findings suggest a potential of nitazoxanide to be repurposed as a new antitumor agent for inhibition of c-Myc-associated neoplasia. Our work also demonstrated the unique advantage of molecular imaging in accelerating discovery of drugs for c-Myc-targeted cancer therapy.

Nitazoxanide suppresses IL-6 production in LPS-stimulated mouse macrophages and TG-injected mice

Suppression of interleukin (IL)-6 production has beneficial effects against various inflammatory diseases. Through a rapid screening system, we found that nitazoxanide, or 2-acetyloxy-N-(5-nitro-2-thiazolyl) benzamide, which is a well-known antiparasitic agent, suppressed lipopolysaccharide (LPS)-induced production of IL-6 from RAW 264.7 cells and mouse peritoneal macrophages, with 50% inhibitory concentrations (IC(50)s) of 1.54 mM and 0.17 mM, respectively. Nitazoxanide also inhibited the LPS-induced expression of IL-6 mRNA in RAW 264.7 cells. To investigate the effects of nitazoxanide in vivo, we orally administered nitazoxanide at a dose of 100mg/kg to mice 2h before a 1-mL intraperitoneal injection of 4% thioglycollate (TG). Six hours after TG injection, plasma IL-6 levels were markedly lower (by 90%) than the levels in vehicle-treated mice. These data suggest that nitazoxanide could be a promising lead compound for agents against various diseases associated with overproduction of IL-6.

Novel Helicobacter pylori therapeutic targets: the unusual suspects

Understanding the current status of the discovery and development of anti-Helicobacter therapies requires an overview of the searches for therapeutic targets performed to date. A summary is given of the very substantial body of work conducted in the quest to find Helicobacter pylori genes that could be suitable candidates for therapeutic intervention. The products of most of these genes perform metabolic functions, and others have roles in growth, cell motility and colonization. The genes identified as potential targets have been organized into three categories according to their degree of characterization. A short description and evaluation is provided of the main candidates in each category. Investigations of potential therapeutic targets have generated a wealth of information about the physiology and genetics of H. pylori, and its interactions with the host, but have yielded little by way of new therapies.

Effects of nitazoxanide on pharmacokinetics and pharmacodynamics of a single dose of warfarin

PURPOSE

The effects of nitazoxanide on warfarin pharmacokinetics and pharmacodynamics are examined.

METHODS

This was a Phase I, single-center, open-label, randomized, two-way, crossover study. Secondary endpoints included an evaluation of the effect of nitazoxanide on coagulation parameters observed after a single dose of warfarin and an assessment of the overall tolerability of study treatments. Fourteen healthy men were selected for the study. The study consisted of two treatment periods (Treatment A and Treatment B), each lasting 6 days, with a washout period of at least 21 days between both warfarin intakes. All subjects were scheduled to receive both Treatment A and Treatment B, according to the randomization list. Treatment A consisted of a single oral dose of 25 mg warfarin sodium (five 5-mg tablets). Treatment B consisted of a single oral intake of 25 mg warfarin sodium (five 5-mg tablets) and one 500-mg tablet of nitazoxanide (with nitazoxanide 500 mg continued twice daily for up to 6 days).

RESULTS

All 14 subjects received Treatment B, and 13 of the 14 subjects received Treatment A. Pharmacokinetic results were similar in both treatments, and pharmacodynamic parameters were similar in both treatments. Fourteen adverse events occurred in eight subjects after administration of at least one dose of the study drug. Eleven adverse events occurred in six subjects after treatment with warfarin and nitazoxanide, and three adverse events occurred in two subjects after treatment with warfarin alone. At discharge, a high hemoglobin level and a low total bilirubin level were reported in both groups.

CONCLUSION

Coadministration of nitazoxanide twice daily for six days did not affect the pharmacokinetic or pharmacodynamic properties of a single 25-mg dose of warfarin sodium. Administration of a single dose of warfarin or combined administration of a single dose of warfarin and multiple doses of nitazoxanide appeared safe and well tolerated.

Current Approaches to the Treatment of Gastrointestinal Infections: Focus on Nitazoxanide

Nitazoxanide is a broad-spectrum agent active against several protozoa, helminths, and bacteria, including C. difficile and H. pylori. It is available as an oral tablet and suspension, both with adequate bioavailability. Nitazoxanide is associated with minimal side effects, has an acceptable safety profile, and has been classified as a pregnancy category B agent. It is 99% protein bound, which could result in drug interactions. It is the preferred agent for the treatment of Cryptospordiosis and Giardiasis in immunocompetent patients and has shown promise for the treatment of rotavirus, mild to moderate initial C. difficile infection, refractory C. difficile infection, Amoebiasis, Blastocystosis, and Taenia saginata.

Brugia malayi: Effects of nitazoxanide and tizoxanide on adult worms and microfilariae of filarial nematodes

There is an urgent need for safe and effective antifilarials. Prior studies have shown that the nitazoxanide (NTZ) exhibits broad activity against anaerobic bacteria, protozoa, and certain intestinal helminths. We examined the effects of NTZ and tizoxanide (TZ) on Brugia malayi nematodes in vitro and in vivo. In vitro, NTZ and TZ reduced worm motility and viability in a dose-dependent manner. Worm viability was reduced by 50% with both compounds at 2.5 and 20 microg/ml killed adult worms. NTZ or TZ (5 microg/ml) significantly reduced microfilaria release. These compounds blocked worm's embryogenesis, and decreased microfilarial motility and viability. Treated worms had damaged cuticles and abnormal mitochondria. Wolbachia were not cleared by NTZ or TZ treatment. Neither NTZ nor TZ cleared adult worms or microfilariae in infected gerbils. These results show that NTZ and TZ have potent effects on B. malayi nematodes in vitro. However, they were not effective in vivo.

Nitazoxanide: clinical studies of a broad-spectrum anti-infective agent

Nitazoxanide is a new compound with broad-spectrum activity against numerous intestinal protozoa, helminths and anaerobic bacteria. It is approved for the treatment of diseases caused by Giardia intestinalis and Cryptosporidium species. The drug is well tolerated, with few side effects and requires a short course of treatment. Further investigations regarding its use in patients with AIDS is needed. Nitazoxanide represents a significant advance in the treatment of intestinal parasitic infections worldwide.

Nitazoxanide: a review of its use in the treatment of gastrointestinal infections

Nitazoxanide (Alinia, Daxon, Dexidex, Paramix, Kidonax, Colufase, Annita) has in vitro activity against a variety of microorganisms, including a broad range of protozoa and helminths. Nitazoxanide is effective in the treatment of protozoal and helminthic infections, including Cryptosporidium parvum or Giardia lamblia, in immunocompetent adults and children, and is generally well tolerated. 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.

Characterization of Giardia lamblia WB C6 clones resistant to nitazoxanide and to metronidazole

OBJECTIVES

The characterization of Giardia lamblia WB C6 strains resistant to metronidazole and to the nitro-thiazole nitazoxanide [2-acetolyloxy-N-(5-nitro 2-thiazolyl) benzamide] as the parent compound of thiazolides, a novel class of anti-infective drugs with a broad spectrum of activities against a wide variety of helminths, protozoa and enteric bacteria.

METHODS

Issuing from G. lamblia WB C6, we have generated two strains exhibiting resistance to nitazoxanide (strain C4) and to metronidazole (strain C5) and determined their susceptibilities to both drugs. Using quantitative RT-PCR, we have analysed the expression of genes that are potentially involved in resistance formation, namely genes encoding pyruvate oxidoreductases (POR1 and POR2), nitroreductase (NR), protein disulphide isomerases (PDI2 and PDI4) and variant surface proteins (VSPs; TSA417). We have cloned and expressed PDI2 and PDI4 in Escherichia coli. Using an enzyme assay based on the polymerization of insulin, we have determined the activities of both enzymes in the presence and absence of nitazoxanide.

RESULTS

Whereas C4 was cross-resistant to nitazoxanide and to metronidazole, C5 was resistant only to metronidazole. Transcript levels of the potential targets for nitro-drugs POR1, POR2 and NR were only slightly modified, PDI2 transcript levels were increased in both resistant strains and PDI4 levels in C4. This correlated with the findings that the functional activities of recombinant PDI2 and PDI4 were inhibited by nitazoxanide. Moreover, drastic changes were observed in VSP gene expression.

CONCLUSIONS

These results suggest that resistance formation in Giardia against nitazoxanide and metronidazole is linked, and possibly mediated by, altered gene expression in drug-resistant strains compared with non-resistant strains of Giardia.

Antiparasitic drug nitazoxanide inhibits the pyruvate oxidoreductases of Helicobacter pylori, selected anaerobic bacteria and parasites, and Campylobacter jejuni

Nitazoxanide (NTZ) exhibits broad-spectrum activity against anaerobic bacteria and parasites and the ulcer-causing pathogen Helicobacter pylori. Here we show that NTZ is a noncompetitive inhibitor (K(i), 2 to 10 microM) of the pyruvate:ferredoxin/flavodoxin oxidoreductases (PFORs) of Trichomonas vaginalis, Entamoeba histolytica, Giardia intestinalis, Clostridium difficile, Clostridium perfringens, H. pylori, and Campylobacter jejuni and is weakly active against the pyruvate dehydrogenase of Escherichia coli. To further mechanistic studies, the PFOR operon of H. pylori was cloned and overexpressed in E. coli, and the multisubunit complex was purified by ion-exchange chromatography. Pyruvate-dependent PFOR activity with NTZ, as measured by a decrease in absorbance at 418 nm (spectral shift from 418 to 351 nm), unlike the reduction of viologen dyes, did not result in the accumulation of products (acetyl coenzyme A and CO(2)) and pyruvate was not consumed in the reaction. NTZ did not displace the thiamine pyrophosphate (TPP) cofactor of PFOR, and the 351-nm absorbing form of NTZ was inactive. Optical scans and (1)H nuclear magnetic resonance analyses determined that the spectral shift (A(418) to A(351)) of NTZ was due to protonation of the anion (NTZ(-)) of the 2-amino group of the thiazole ring which could be generated with the pure compound under acidic solutions (pK(a) = 6.18). We propose that NTZ(-) intercepts PFOR at an early step in the formation of the lactyl-TPP transition intermediate, resulting in the reversal of pyruvate binding prior to decarboxylation and in coordination with proton transfer to NTZ. Thus, NTZ might be the first example of an antimicrobial that targets the "activated cofactor" of an enzymatic reaction rather than its substrate or catalytic sites, a novel mechanism that may escape mutation-based drug resistance.

Nitazoxanide, a broad-spectrum thiazolide anti-infective agent for the treatment of gastrointestinal infections

Colonisation of the gastrointestinal tract by anaerobic bacteria, protozoa, trematodes, cestodes and/or nematodes and other infectious pathogens, including viruses, represents a major cause of morbidity and mortality in Africa, South America and southeast Asia, as well as other parts of the world. Nitazoxanide is a member of the thiazolide class of drugs with a documented broad spectrum of activity against parasites and anaerobic bacteria. Moreover, the drug has recently been reported to have a profound activity against hepatitis C virus infection. In addition, nitazoxanide exhibits anti-inflammatory properties, which have prompted clinical investigations for its use in Crohn's disease. Studies with nitazoxanide derivatives have determined that there must be significantly different mechanisms of action acting on intracellular versus extracellular pathogens. An impressive number of clinical studies have shown that the drug has an excellent bioavailability in the gastrointestinal tract, is fast acting and highly effective against gastrointestinal bacteria, protozoa and helminthes. A recent Phase II study has demonstrated viral response (hepatitis C) to monotherapy, with a low toxicity and an excellent safety profile over 24 weeks of treatment. Pre-clinical studies have indicated that there is a potential for application of this drug against other diseases, not primarily affecting the liver or the gastrointestinal tract.

Mutations in Helicobacter pylori porD and oorD genes may contribute to furazolidone resistance

AIM

To determine the rate of furazolidone resistance of Helicobacter pylori (H. pylori) isolated from gastric biopsy specimens and to explore the relationship between genetic mutations in porD and oorD genes of H. pylori and its resistance to the antibiotic.

METHODS

Gastric biopsy was performed in 83 adult patients aged 31-77 years with gastric complaints. H. pylori was isolated from biopsy specimens of 46 patients. E-test and 2-fold agar dilution method were used to determine the rate of H. pylori resistance to furazolidone. The genes porD and oorD from susceptible and resistant isolates were amplified by polymerase chain reaction (PCR), and their PCR products were sequenced.

RESULTS

Resistance to furazolidone was found in 8.7% of H. pylori isolates and 6 mutations were detected in porD and oorD genes of the resistant isolates. Three mutations--G353A, A356G, and C357T--occurred in porD and the other mutations--A041G, A122G, C349A(G)--occurred in oorD genes.

CONCLUSIONS

Changes in 6 amino acids may be associated with the resistance of H. pylori to furazolidone.

Activities of tizoxanide and nitazoxanide compared to those of five other thiazolides and three other agents against anaerobic species

Agar dilution was used, and MICs of metronidazole, tizoxanide, nitazoxanide, denitrotizoxanide, RM 4803, RM 4807, RM 4809, RM 4819, amoxicillin-clavulanate, and clindamycin were measured against 412 anaerobes. Nitazoxanide, tizoxanide, RM 4807, and RM 4809 were active against all groups, except for gram-positive non-spore-forming rods with 50% minimum inhibitory concentrations (when the latter were excluded) of 1 to 2 microg/ml and 90% minimum inhibitory concentrations of 4 to 8 microg/ml, respectively. Metronidazole MICs were usually lower against all groups except clostridia.

In vitro effects of thiazolides on Giardia lamblia WB clone C6 cultured axenically and in coculture with Caco2 cells

The thiazolides represent a novel class of anti-infective drugs, with the nitrothiazole nitazoxanide [2-acetolyloxy-N-(5-nitro 2-thiazolyl) benzamide] (NTZ) as the parent compound. NTZ exhibits a broad spectrum of activities against a wide variety of helminths, protozoa, and enteric bacteria infecting animals and humans. In vivo, NTZ is rapidly deacetylated to tizoxanide (TIZ), which exhibits similar activities. We have here comparatively investigated the in vitro effects of NTZ, TIZ, a number of other modified thiazolides, and metronidazole (MTZ) on Giardia lamblia trophozoites grown under axenic culture conditions and in coculture with the human cancer colon cell line Caco2. The modifications of the thiazolides included, on one hand, the replacement of the nitro group on the thiazole ring with a bromide, and, on the other hand, the differential positioning of methyl groups on the benzene ring. Of seven compounds with a bromo instead of a nitro group, only one, RM4820, showed moderate inhibition of Giardia proliferation in axenic culture, but not in coculture with Caco2 cells, with a 50% inhibitory concentration (IC50) of 18.8 microM; in comparison, NTZ and tizoxanide had IC50s of 2.4 microM, and MTZ had an IC50 of 7.8 microM. Moreover, the methylation or carboxylation of the benzene ring at position 3 resulted in a significant decrease of activity, and methylation at position 5 completely abrogated the antiparasitic effect of the nitrothiazole compound. Trophozoites treated with NTZ showed distinct lesions on the ventral disk as soon as 2 to 3 h after treatment, whereas treatment with metronidazole resulted in severe damage to the dorsal surface membrane at later time points.

Use of nitazoxanide for gastrointestinal tract infections: Treatment of protozoan parasitic infection and beyond

The United States Food and Drug Administration has approved the parasiticidal agent nitazoxanide for treatment of diarrhea caused by Giardia lamblia/intestinalis or Cryptosporidium parvum. This novel agent has a broad spectrum of activity against many other gastrointestinal pathogens, including bacteria, roundworms, flatworms, and flukes. Nitazoxanide is used in many areas of the world, especially in Central and South America, as a broad-spectrum parasiticidal agent in adults and children. Nitazoxanide appears to be well tolerated, has a relatively low incidence of adverse effect, and displays no significant known drug-to-drug interactions. Recently, preliminary reports indicate that nitazoxanide may be an effective treatment for Clostridium difficile-associated diarrhea as well. Future work will likely solidify and further expand the role of nitazoxanide in the treatment of a wide range of intestinal pathogens.

Identification of Isoflavone Derivatives as Effective Anticryptosporidial Agents in Vitro and in Vivo

We report the preparation and antiparasitic activity in vitro and in vivo of a series of isoflavone derivatives related to genistein. These analogues retain the 5,7-dihydroxyisoflavone core of genistein: direct genistein analogues (2-H isoflavones), 2-carboethoxy isoflavones, and the precursor deoxybenzoins were all evaluated. Excellent in vitro activity against Cryptosporidium parvum was observed for both classes of isoflavones in cell cultures, and the lead compound 19, RM6427, shows high in vivo efficacy against an experimental infection.