Randomized clinical study of nitazoxanide compared to metronidazole in the treatment of symptomatic giardiasis in children from Northern Peru

Glucuronidation of tizoxanide, an active metabolite of nitazoxanide, in liver and small intestine: Species differences in humans, monkeys, dogs, rats, and mice and responsible UDP-glucuronosyltransferase isoforms in humans

Tizoxanide (TZX) is an active metabolite of nitazoxanide (NTZ) originally developed as an antiparasitic agent, and is predominantly metabolized into TZX glucuronide. In the present study, TZX glucuronidation by the liver and intestinal microsomes of humans, monkeys, dogs, rats, and mice, and recombinant human UDP-glucuronosyltransferase (UGT) were examined. The kinetics of TZX glucuronidation by the liver and intestinal microsomes followed the Michaelis-Menten or biphasic model, with species-specific variations in the intrinsic clearance (CLint). Rats and mice exhibited the highest CLint values for liver microsomes, while mice and rats were the highest for intestinal microsomes. Among human UGTs, UGT1A1 and UGT1A8 demonstrated significant glucuronidation activity. Estradiol and emodin inhibited TZX glucuronidation activities in the human liver and intestinal microsomes in a dose-dependent manner, with emodin showing stronger inhibition in the intestinal microsomes. These results suggest that the roles of UGT enzymes in TZX glucuronidation in the liver and small intestine differ extensively across species and that UGT1A1 and/or UGT1A8 mainly contribute to the metabolism and elimination of TZX in humans. This study presents the relevant and novel-appreciative report on TZX metabolism catalyzed by UGT enzymes, which may aid in the assessment of the antiparasitic, antibacterial, and antiviral activities of NTZ for the treatment of various infections.

Impact of azithromycin and nitazoxanide on the enteric infections and child growth: Findings from the Early Life Interventions for Childhood Growth and Development in Tanzania (ELICIT) trial

BACKGROUND

Early childhood enteric infection with Shigella/EIEC, enteroaggregative E. coli (EAEC), Campylobacter, and Giardia has been associated with reduced child growth, yet a recent randomized trial of antimicrobial therapy to reduce these infections did not improve growth outcomes. To interrogate this discrepancy, we measured the enteric infections from this study.

METHODS

We leveraged the Early Life Interventions for Childhood Growth and Development in Tanzania (ELICIT) trial, a randomized double-blind placebo-controlled trial of antimicrobial therapy with azithromycin and nitazoxanide provided quarterly to infants from 6 to 15 months of age. We tested 5,479 stool samples at time points across the study for 34 enteropathogens using quantitative PCR.

RESULTS

There was substantial carriage of enteropathogens in stool. Azithromycin administration led to reductions in Campylobacter jejuni/coli, enteroaggregative E. coli, and Shigella/EIEC (absolute risk difference ranged from -0.06 to 0.24) 2 weeks after treatment however there was no effect after 3 months. There was no difference in Giardia after nitazoxanide administration (ARR 0.03 at the 12 month administration). When examining the effect of azithromycin versus placebo on the subset of children infected with specific pathogens at the time of treatment, a small increase in weight-for-age Z score was seen only in those infected with Campylobacter jejuni/coli (0.10 Z score, 95% CI -0.01-0.20; length-for-age Z score 0.07, 95% CI -0.06-0.20).

CONCLUSION

The antimicrobial intervention of quarterly azithromycin plus or minus nitazoxanide led to only transient decreases in enteric infections with Shigella/EIEC, enteroaggregative E. coli (EAEC), Campylobacter, and Giardia. There was a trend towards improved growth in children infected with Campylobacter that received quarterly azithromycin.

Antiparasitic Drugs against SARS-CoV-2: A Comprehensive Literature Survey

More than two years have passed since the viral outbreak that led to the novel infectious respiratory disease COVID-19, caused by the SARS-CoV-2 coronavirus. Since then, the urgency for effective treatments resulted in unprecedented efforts to develop new vaccines and to accelerate the drug discovery pipeline, mainly through the repurposing of well-known compounds with broad antiviral effects. In particular, antiparasitic drugs historically used against human infections due to protozoa or helminth parasites have entered the main stage as a miracle cure in the fight against SARS-CoV-2. Despite having demonstrated promising anti-SARS-CoV-2 activities in vitro, conflicting results have made their translation into clinical practice more difficult than expected. Since many studies involving antiparasitic drugs are currently under investigation, the window of opportunity might be not closed yet. Here, we will review the (controversial) journey of these old antiparasitic drugs to combat the human infection caused by the novel coronavirus SARS-CoV-2.

Effect of scheduled antimicrobial and nicotinamide treatment on linear growth in children in rural Tanzania: A factorial randomized, double-blind, placebo-controlled trial

BACKGROUND

Stunting among children in low-resource settings is associated with enteric pathogen carriage and micronutrient deficiencies. Our goal was to test whether administration of scheduled antimicrobials and daily nicotinamide improved linear growth in a region with a high prevalence of stunting and enteric pathogen carriage.

METHODS AND FINDINGS

We performed a randomized, 2 × 2 factorial, double-blind, placebo-controlled trial in the area around Haydom, Tanzania. Mother-child dyads were enrolled by age 14 days and followed with monthly home visits and every 3-month anthropometry assessments through 18 months. Those randomized to the antimicrobial arm received 2 medications (versus corresponding placebos): azithromycin (single dose of 20 mg/kg) at months 6, 9, 12, and 15 and nitazoxanide (3-day course of 100 mg twice daily) at months 12 and 15. Those randomized to nicotinamide arm received daily nicotinamide to the mother (250 mg pills months 0 to 6) and to the child (100 mg sachets months 6 to 18). Primary outcome was length-for-age z-score (LAZ) at 18 months in the modified intention-to-treat group. Between September 5, 2017 and August 31, 2018, 1,188 children were randomized, of whom 1,084 (n = 277 placebo/placebo, 273 antimicrobial/placebo, 274 placebo/nicotinamide, and 260 antimicrobial/nicotinamide) were included in the modified intention-to-treat analysis. The study was suspended for a 3-month period by the Tanzanian National Institute for Medical Research (NIMR) because of concerns related to the timing of laboratory testing and the total number of serious adverse events (SAEs); this resulted in some participants receiving their final study assessment late. There was a high prevalence of stunting overall (533/1,084, 49.2%). Mean 18-month LAZ did not differ between groups for either intervention (mean LAZ with 95% confidence interval [CI]: antimicrobial: -2.05 CI -2.13, -1.96, placebo: -2.05 CI -2.14, -1.97; mean difference: 0.01 CI -0.13, 0.11, p = 0.91; nicotinamide: -2.06 CI -2.13, -1.95, placebo: -2.04 CI -2.14, -1.98, mean difference 0.03 CI -0.15, 0.09, p = 0.66). There was no difference in LAZ for either intervention after adjusting for possible confounders (baseline LAZ, age in days at 18-month measurement, ward, hospital birth, birth month, years of maternal education, socioeconomic status (SES) quartile category, sex, whether the mother was a member of the Datoga tribe, and mother's height). Adverse events (AEs) and SAEs were overall similar between treatment groups for both the nicotinamide and antimicrobial interventions. Key limitations include the absence of laboratory measures of pathogen carriage and nicotinamide metabolism to provide context for the negative findings.

CONCLUSIONS

In this study, we observed that neither scheduled administration of azithromycin and nitazoxanide nor daily provision of nicotinamide was associated with improved growth in this resource-poor setting with a high force of enteric infections. Further research remains critical to identify interventions toward improved early childhood growth in challenging conditions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03268902.

Efficacy and tolerability of quinacrine monotherapy and albendazole plus chloroquine combination therapy in nitroimidazole-refractory giardiasis: a TropNet study

BACKGROUND

Giardiasis failing nitroimidazole first-line treatment is an emerging clinical problem in returning European travelers. We present data on the efficacy and tolerability of two second-line treatment regimens.

METHODS

Prospective, open-label, multi-center study assessing the efficacy and tolerability of quinacrine monotherapy (100mg TID for 5 days) and albendazole plus chloroquine combination therapy (400mg BID plus 155mg BID for 5 days) in nitroimidazole-refractory giardiasis, defined as cases with persisting or relapsing infection despite single or repeated courses of nitroimidazole treatment. The defined endpoints were the clinical outcome, assessed by a questionnaire, at week 5 after treatment and the parasitological outcome, assessed by microscopy of 2 stool samples, ≥2-≤5 weeks after treatment.

RESULT

106 patients were included in the study. Quinacrine achieved clinical and parasitological cure in 81% (59/73) and 100% (56/56), respectively. Albendazole plus chloroquine achieved clinical and parasitological cure in 36% (12/33) and 48% (12/25), respectively. All patients (9/9) who clinically and parasitologically failed albendazole plus chloroquine treatment and opted for re-treatment with quinacrine achieved clinical cure. Mild to moderate treatment-related adverse events were reported by 45% and 30% of patients treated with quinacrine and albendazole plus chloroquine, respectively. One patient treated with quinacrine developed severe neuropsychiatric side effects. The majority of nitroimidazole-refractory Giardia infections (57%) were acquired in India.

CONCLUSION

Quinacrine was a highly effective treatment in nitroimidazole-refractory giardiasis, but patients should be cautioned on the low risk of severe neuropsychiatric adverse event. Albendazole plus chloroquine had a low cure rate in nitroimidazole-refractory giardiasis. Nitroimidazole-refractory giardiasis was primarily seen in travelers returning from India.

Giardiasis treatment: an update with a focus on refractory disease

PURPOSE OF REVIEW

Giardiasis remains a common cause of diarrhea and intestinal enteropathy globally. Here we give an overview of clinical treatment studies and discuss potential mechanisms and molecular targets for in-vitro testing of drug resistance.

RECENT FINDINGS

Giardia is a cause of disease both in diarrheal and nondiarrheal cases. The prevalence of treatment refractory giardiasis is increasing. Recent studies reveal 5-nitroimidazole refractory infection occurs in up to 50% of cases. Mechanisms of drug resistance are not known. Placebo controlled studies of drug efficacy, taking the self-limiting course of giardiasis into account, has not been reported. No randomized controlled trials of treatment of refractory infection have been performed the last 25 years. Based on the clinical studies reported, combination treatment with a 5-nitroimidazole and a benzimidazole is more effective than repeated courses of 5-nitroimidazole or monotherapies in refractory cases. Quinacrine is effective in refractory cases, but potentially severe side effects limit its use.

SUMMARY

A combination of a 5-nitroimidazole and albendazole or mebendazole, and quinacrine monotherapy, are rational choices in nitroimidazole refractory infections, but randomized controlled studies are needed. Further research into more recent clinical isolates is necessary to uncover mechanisms for the increase in metronidazole refractory giardiasis observed during the last decade.

Risk factors for and management of metronidazole-refractory giardiasis in international travellers: A retrospective analysis

BACKGROUND

Giardia lamblia is a common cause of diarrhoea in returning travellers. Failure of the recommended first-line treatment, metronidazole, has frequently been observed. Recommendations for treatment of metronidazole-refractory giardiasis lack clarity and evidence.

METHODS

We conducted a retrospective data analysis of returned travellers with confirmed giardiasis at the Bernhard-Nocht-Clinic in Hamburg, Germany, between 2007 and 2016.

RESULTS

We identified 339 cases of giardiasis, mostly acquired in South Asia (n = 157). 308 patients received metronidazole as first-line treatment, leading to treatment failure in 93 cases. Statistical analysis suggested by far the highest risk of metronidazole treatment failure for travellers returning from South Asia (Odds Ratio 8.73). Second-line therapy consisted of various different therapy regimens. Combination therapy as second-line treatment seemed to be more effective than monotherapy. A repeat course of metronidazole proved to be futile.

CONCLUSION

This study reveals a strikingly low effectiveness of metronidazole, especially in patients returning from South Asia. Second-line treatment showed inconsistency of regimens and yielded unsatisfactory results. These findings require reconsideration of treatment strategies for giardiasis. Large prospective trials are urgently needed to assess new first-line treatment options and to help implement advice for effective, agreed second-line treatment strategies. Translational projects should be created to link the understanding of resistance mechanisms with epidemiological data and clinical outcome.

Strategy, Progress, and Challenges of Drug Repurposing for Efficient Antiviral Discovery

Emerging or re-emerging viruses are still major threats to public health. Prophylactic vaccines represent the most effective way to prevent virus infection; however, antivirals are more promising for those viruses against which vaccines are not effective enough or contemporarily unavailable. Because of the slow pace of novel antiviral discovery, the high disuse rates, and the substantial cost, repurposing of the well-characterized therapeutics, either approved or under investigation, is becoming an attractive strategy to identify the new directions to treat virus infections. In this review, we described recent progress in identifying broad-spectrum antivirals through drug repurposing. We defined the two major categories of the repurposed antivirals, direct-acting repurposed antivirals (DARA) and host-targeting repurposed antivirals (HTRA). Under each category, we summarized repurposed antivirals with potential broad-spectrum activity against a variety of viruses and discussed the possible mechanisms of action. Finally, we proposed the potential investigative directions of drug repurposing.

Synthesis, in vitro bioassays, and computational study of heteroaryl nitazoxanide analogs

Antiprotozoal drug nitazoxanide (NTZ) has shown diverse pharmacological properties and has appeared in several clinical trials. Herein we present the synthesis, characterization, in vitro biological investigation, and in silico study of four hetero aryl amide analogs of NTZ. Among the synthesized molecules, compound 2 and compound 4 exhibited promising antibacterial activity against Escherichia coli (E. coli), superior to that displayed by the parent drug nitazoxanide as revealed from the in vitro antibacterial assay. Compound 2 displayed zone of inhibition of 20 mm, twice as large as the parent drug NTZ (10 mm) in their least concentration (12.5 µg/ml). Compound 1 also showed antibacterial effect similar to that of nitazoxanide. The analogs were also tested for in vitro cytotoxic activity by employing cell counting kit-8 (CCK-8) assay technique in HeLa cell line, and compound 2 was identified as a potential anticancer agent having IC50 value of 172 µg which proves it to be more potent than nitazoxanide (IC50  = 428 µg). Furthermore, the compounds were subjected to molecular docking study against various bacterial and cancer signaling proteins. The in vitro test results corroborated with the in silico docking study as compound 2 and compound 4 had comparatively stronger binding affinity against the proteins and showed a higher docking score than nitazoxanide toward human mitogen-activated protein kinase (MAPK9) and fatty acid biosynthesis enzyme (FabH) of E. coli. Moreover, the docking study demonstrated dihydrofolate reductase (DHFR) and thymidylate synthase (TS) as probable new targets for nitazoxanide and its synthetic analogs. Overall, the study suggests that nitazoxanide and its analogs can be a potential lead compound in the drug development.

Effect of nitazoxanide on diarrhea: A systematic review and network meta-analysis of randomized controlled trials

We aimed to systematically review evidence pertaining to the safety and efficacy of nitazoxanide in treating infectious diarrhea. On September 21, 2017, we identified relevant studies using 12 databases. The estimates of the included studies were pooled as a risk ratio (RR). We conducted a network and pairwise random-effects meta-analysis for both direct and indirect comparisons of different organisms that are known to cause diarrhea. The primary and secondary analysis outcomes were clinical response until cessation of illness, parasitological response and adverse events. We included 18 studies in our analysis. In cryptosporidiosis, the overall estimate favored nitazoxanide in its clinical response in comparison with placebo RR 1.46 [95% CI 1.22-1.74; P-value <0.0001]. Network meta-analysis among patients with Giardia intestinalis showed an increase in the probability of diarrheal cessation and parasitological responses in comparison with placebo, RR 1.69 [95% CI 1.08-2.64, P-score 0.27] and RR 2.91 [95% CI 1.72-4.91, P-score 0.55] respectively. In Clostridium difficile infection, the network meta-analysis revealed a non-significantly superior clinical response effect of nitazoxanide to metronidazole 31 days after treatment RR 1.21 [95% CI 0.87-1.69, P-score 0.26]. In Entamoeba histolytica, the overall estimate significantly favored nitazoxanide in parasitological response with placebo RR 1.80 [95% CI 1.35-2.40, P-value < 0.001]. We highlighted the effectiveness of nitazoxanide in the cessation of diarrhea caused by Cryptosporidium, Giardia intestinalis and Entamoeba histolytica infection. We also found significant superiority of NTZ to metronidazole in improving the clinical response to G. intestinalis, thus it may be a suitable candidate for treating infection-induced diarrhea. To prove the superiority of NTZ during a C. difficile infection may warrant a larger-scale clinical trial since its superiority was deemed insignificant. We recommend nitazoxanide as an appropriate option for treating infectious diarrhea.

Repositioning of Anthelmintic Drugs for the Treatment of Cancers of the Digestive System

Tumors of the digestive system, when combined together, account for more new cases and deaths per year than tumors arising in any other system of the body and their incidence continues to increase. Despite major efforts aimed at discovering and validating novel and effective drugs against these malignancies, the process of developing such drugs remains lengthy and costly, with high attrition rates. Drug repositioning (also known as drug repurposing), that is, the process of finding new uses for approved drugs, has been gaining popularity in oncological drug development as it provides the opportunity to expedite promising anti-cancer agents into clinical trials. Among the drugs considered for repurposing in oncology, compounds belonging to some classes of anthelmintics—a group of agents acting against infections caused by parasitic worms (helminths) that colonize the mammalian intestine—have shown pronounced anti-tumor activities and attracted particular attention due to their ability to target key oncogenic signal transduction pathways. In this review, we summarize and discuss the available experimental and clinical evidence about the use of anthelmintic drugs for the treatment of cancers of the digestive system.

Nitazoxanide in the Treatment of Intestinal Parasitic Infections in Children: A Systematic Review and Meta-Analysis

OBJECTIVES

To evaluate the efficacy and safety of nitazoxanide in intestinal parasitic infections in children.

METHODS

Four databases, PubMed, EMBASE, Web of Science and Cochrane Library, have been systematically searched from the inception of each database up to March 1st, 2019. The enrolled studies were limited to randomized clinical trials in children, comparing nitazoxanide with placebo or other antiparasitic drugs. The data extraction and quality assessment of pooled studies were conducted by two reviewers independently. For meta-analysis, Stata12.0 was used and a randomized effect model or a fixed effect model was selected according to the outcomes of heterogeneity test.

RESULTS

A total of 1645 subjects in 13 randomized controlled trials (RCTs) were enrolled, including 768 cases in the trial group and 877 cases in the control group. The effect of nitazoxanide vs. placebo and other antiparasitic drugs on the excretion rate of pathogens was uncertain (OR = 2.06, 95%CI [1.01,4.20], P = 0.047; I² = 84.7%; very low quality evidence). Compared with placebo, subgroup analysis suggested that nitazoxanide could significantly improve the excretion rate of pathogens (OR = 7.01, 95%CI [1.82,26.94], P = 0.005; I² = 79.1%; moderate quality evidence), while it made little or no difference compared with antiparasitic drugs (OR = 0.72, 95%CI [0.47,1.09], P = 0.124; I² = 33.1%; low quality evidence). Meanwhile, nitazoxanide might increase the remission rate of diarrhea with OR = 5.12, 95%CI [2.00,13.08], P = 0.001; I² = 72.3%; low quality evidence). However, it might also increase the rate of adverse events (OR = 1.47, 95%CI [1.05,2.07], P = 0.026; I² = 44.7%; low quality evidence).

CONCLUSIONS

The authors are uncertain whether or not nitazoxanide could improve the excretion rate of pathogens. Based on low-certainty evidence, nitazoxanide may improve the remission rate of diarrhea in children with intestinal parasite infections, but it may be associated with an increased risk of adverse reactions. Hence, more RCTs with a low risk of bias are still needed to assess the efficacy and safety of nitazoxanide.

Efficacy and Safety of Nitazoxanide in Addition to Standard of Care for the Treatment of Severe Acute Respiratory Illness

BACKGROUND

Effective therapeutics for respiratory viruses are needed. Early data suggest that nitazoxanide (NTZ) may be beneficial for treating acute respiratory viral illness.

METHODS

From March 2014 through March 2017, a double-blind, placebo-controlled trial was conducted in 260 participants ≥1 year old hospitalized with influenza-like illness at 6 hospitals in Mexico. Participants were randomized 1:1 to NTZ (age ≥12 years, 600 mg twice daily; age 4-11 years and 1-3 years, 200 or 100 mg twice daily, respectively) or placebo for 5 days in addition to standard of care. The primary endpoint was time from first dose to hospital discharge. Influenza reverse-transcription polymerase chain reaction and Respifinder 22 multiplex test were used for virus detection.

RESULTS

Of 260 participants enrolled, 257 were randomized and took at least 1 dose of study treatment (intention-to-treat population): 130 in the NTZ group and 127 in the placebo group. The Kaplan-Meier estimate of the median duration of hospitalization was 6.5 (interquartile range [IQR], 4.0-9.0) days in the NTZ group vs 7.0 (IQR, 4.0-9.0) days in the placebo group (P = .56). Duration of hospitalization between the 2 treatments was similar in children (P = .29) and adults (P = .62), influenza A and B (P = .32), and other respiratory viruses. Seven (5.4%) and 6 (4.7%) participants in the NTZ and placebo groups, respectively, reported serious adverse events.

CONCLUSIONS

Treatment with NTZ did not reduce the duration of hospital stay in severe influenza-like illness. Further analyses based on age and evaluations by virus did not reveal any subgroups that appeared to benefit from NTZ.

CLINICAL TRIALS REGISTRATION

NCT02057757.

Treatment-refractory giardiasis: challenges and solutions

Giardia is the commonest parasitic diarrheal pathogen affecting humans and a frequent cause of waterborne/foodborne parasitic diseases worldwide. Prevalence of giardiasis is higher in children, living in poor, low hygiene settings in developing countries, and in travelers returning from highly endemic areas. The clinical picture of giardiasis is heterogeneous, with high variability in severity of clinical disease. It can become chronic or be followed by post-infectious sequelae. An alarming increase in cases refractory to the conventional treatment with nitroimidazoles (ie, metronidazole) has been reported in low prevalence settings, such as European Union countries, especially in patients returning from Asia. In view of its relevance, we aim in this review to recapitulate present clinical knowledge about Giardia, with a special focus on the challenge of treatment-refractory giardiasis. We propose a working definition of clinically drug-resistant giardiasis, summarize knowledge regarding resistance mechanisms, and discuss its clinical management according to research-based evidence and medical practice. Advances in development and identification of novel drugs and potential non-pharmacological alternatives are also reviewed with the overall aim to define knowledge gaps and suggest future directions for research.

Ocular Parasitosis Caused by Protozoan Infection during Travel: Focus on Prevention and Treatment

International travel is rising quickly worldwide. Many people travel to tropical and subtropical areas, where there has been increasing exposure of travelers to infectious pathogens. Ocular parasitic infections are more prevalent in these geographical areas and they can lead to morbidity and mortality, often due to late or misdiagnosis due to the unfamiliarity of health staff with these diseases. This is an up-to-date comprehensive review article that familiarizes physicians with ocular signs and symptoms, treatment, prevention, and geographic distribution of some parasites associated with travel.

Nitazoxanide is active against Mycobacterium leprae

Nitazoxanide (NTZ) is an anti-parasitic drug that also has activity against bacteria, including Mycobacterium tuberculosis. Our data using both radiorespirometry and live-dead staining in vitro demonstrate that NTZ similarly has bactericidal against M. leprae. Further, gavage of M. leprae-infected mice with NTZ at 25mg/kg provided anti-mycobacterial activity equivalent to rifampicin (RIF) at 10 mg/kg. This suggests that NTZ could be considered for leprosy treatment.

Nitazoxanide: a first-in-class broad-spectrum antiviral agent

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. A Phase 2b/3 clinical trial recently published in The Lancet Infectious Diseases found that oral administration of nitazoxanide 600mg twice daily for five days reduced the duration of clinical symptoms and reduced viral shedding compared to placebo in persons with laboratory-confirmed influenza. The same study also suggested a potential benefit for subjects with influenza-like illness who did not have influenza or other documented respiratory viral infection. 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. Nitazoxanide is orally bioavailable and safe with extensive post-marketing experience involving more than 75 million adults and children. 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. It is synergistic with neuraminidase inhibitors, and combination therapy with oseltamivir is being studied in humans as part of ongoing Phase 3 clinical development. 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.

Management of chronic Giardia infection

Advances in our understanding of chronic giardiasis (CG) may improve our care of patients in this stage of the disease. This review proposes a new concept of CG and highlights the recent advances in our understanding and management of this condition. According to this review, management requires, initially, an accurate diagnosis, which may exclude several conditions that can mimic CG. Optimal treatment requires a tailored approach which includes the recognition of the known modifiable causes of this health condition, assessment of symptoms and potential complications, their treatment utilizing, if necessary, a multidisciplinary team, and an ongoing monitoring for the effect of therapy - weighing the efficacy of individual drugs - all of these together may lead to a successful treatment of CG.

Nitazoxanide for chronic hepatitis C

BACKGROUND

Hepatitis C infection is a disease of the liver caused by the hepatitis C virus. The estimated number of chronically infected people with hepatitis C virus worldwide is about 150 million people. Every year, another three to four million people acquire the infection. Chronic hepatitis C is a leading cause of liver-related mortality and morbidity. It is estimated that around 5% to 20% of people with the infection will develop liver cirrhosis, which increases the risk of hepatocellular carcinoma and liver failure. Until 2011, the combination therapy of pegylated interferon-alpha (peginterferon) and ribavirin was the approved standard treatment for chronic hepatitis C. In 2011, first-generation direct-acting antivirals have been licensed, for use in combination with peginterferon and ribavirin for treating hepatitis C virus genotype 1 infection. Nitazoxanide is another antiviral drug with broad antiviral activity and may have potential as an effective alternative, or an addition to standard treatment for the treatment of the hepatitis C virus.

OBJECTIVES

To assess the benefits and harms of nitazoxanide in people with chronic hepatitis C virus infection.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register (last searched April 2013), The Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 3), MEDLINE (Ovid SP, 1948 to April 2013), EMBASE (Ovid SP, 1980 to April 2013), LILACS (1983 to April 2013), and Science Citation Index EXPANDED (ISI Web of Knowledge, 1900 to April 2013), using the search strategies and the expected time spans. We also scanned reference lists of identified studies.We also searched ClinicalTrials.gov and the World Health Organization's International Clinical Trials Registry Platform search portal for registered trials, either completed or ongoing (April 2013).

SELECTION CRITERIA

We included randomised clinical trials that examined the effects of nitazoxanide versus placebo, no intervention, or any other intervention in patients with chronic hepatitis C. We considered any co-intervention, including standard treatment, if delivered to all intervention groups of the randomised trial concerned.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We assessed the risk of systematic errors ('bias') by evaluation of bias risk domains. We used Review Manager 5.2 for the statistical analyses of dichotomous outcome data with risk ratio (RR) and of continuous outcome data with mean difference (MD). For meta-analyses, we used a fixed-effect model and a random-effects model, along with an assessment of heterogeneity. We assessed risk of random errors ('play of chance') using trial sequential analysis. We assessed the quality of the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system to present review results in 'Summary of findings' tables.

MAIN RESULTS

We included seven randomised clinical trials with a total of 538 participants with chronic hepatitis C. Participants were 18 years of age or older, all diagnosed with chronic hepatitis C genotype 1 or 4. All of the trials had a high risk of bias. All of the trials compared nitazoxanide with placebo or no intervention, and six out of seven of the trials included different antiviral co-interventions administered equally to all intervention groups. Only one trial, comparing nitazoxanide plus peginterferon and ribavirin versus no intervention plus peginterferon and ribavirin, provided information that there were no deaths due to any cause or due to chronic hepatitis C (100 participants, very low quality evidence). The relative effect of nitazoxanide versus placebo or no intervention on adverse events was uncertain (37 out of 179 (21%) versus 30 out of 152 (20%); RR 1.10; 95% CI 0.71 to 1.71; I(2) = 65%; four trials; very low quality evidence). Nitazoxanide decreased the risk of failure to achieve sustained virological response when compared with placebo or no intervention (159 out of 290 (55%) versus 133 out of 208 (64%); RR 0.85; 95% CI 0.75 to 0.97; I(2) = 0%; seven trials; low quality evidence) and also the risk of failure to achieve virological end-of-treatment response (125 out of 290 (43%) versus 110 out of 208 (53%); RR 0.81; 95% CI 0.69 to 0.96; I(2) = 46%; seven trials; low quality evidence). Trial sequential analysis supported the meta-analysis result for sustained virological response, but not the meta-analysis for virological end-of-treatment response. Meta-analysis also showed that nitazoxanide did not decrease the number of participants who showed no improvement in alanine aminotransferase and aspartate aminotransferase serum levels when compared with placebo or no intervention (52 out of 97 (54%) versus 47 out of 95 (49%); RR 1.09; 95% CI 0.84 to 1.42; I(2) = 0%; three trials; very low quality evidence). None of the included trials assessed the effects of nitazoxanide on morbidity or on quality of life. Histological changes were only reported on a subset of three participants out of thirteen participants included in a long term-follow-up trial.

AUTHORS' CONCLUSIONS

We found very low quality, or no, evidence on nitazoxanide for clinically- or patient-relevant outcomes, such as all-cause mortality, chronic hepatitis C-related mortality, morbidity, and adverse events in participants with chronic hepatitis C genotype 1 or 4 infection. Our results of no improvement in alanine aminotransferase and aspartate aminotransferase serum levels were also uncertain. No conclusion could be drawn about liver histology because of a lack of data. Our results indicate that nitazoxanide might have an effect on sustained virological response and virological end-of-treatment response. However, both results could be influenced by systematic errors because all the trials included in the review had a high risk of bias. Furthermore, only the beneficial effect on number of participants achieving sustained virological response was supported when we applied trial sequential analysis. The results on virological end-of-treatment response might, therefore, be caused by a random error. We totally lack information on the effects of nitazoxanide in participants with chronic hepatitis C genotypes 2 or 3 infection. More randomised clinical trials with a low risk of bias are needed to assess the effects of nitazoxanide for chronic hepatitis C.

Management of acute infectious diarrhea for children living in resource-limited settings

Acute infectious gastroenteritis continues to be a leading cause of morbidity and mortality in children below 5 years of age, with the majority of deaths concentrated in 35 'low income' countries. In these countries the under five years of age mortality rates reach 100 per 1000 live births, of which a significant proportion are associated with acute diarrhea. Rotavirus, cryptosporidium, Shigella spp and enterotoxigenic Escherichia coli are the main pathogens causing disease in these settings, although other bacteria and parasites can cause moderate to severe disease in different regions and situations. Treatment of children in these setting should be focused on appropriate rehydration, early hospitalization of severely malnourished children, zinc supplementation, and in specific situations, antimicrobials should be considered. The rationale for antimicrobial use should be based on the potential benefits based on published literature and the opportunity for use. This review provides a pathogen-specific update on the potential benefits of antimicrobials and suggests an empirical management approach for children suffering an acute watery or bloody diarrhea in a resource-limited region.

Efficacy of 5-nitroimidazoles for the treatment of giardiasis: a systematic review of randomized controlled trials

Background

Giardiasis is one of the most common causes of diarrheal disease worldwide and 5-nitroimidazoles (5-NI) are the most commonly prescribed drugs for the treatment of giardiasis. We evaluated the efficacy of 5-nitroimidazoles (5-NI) in the treatment of giardiasis in a systematic review of randomized controlled trials (RCTs).

Methodology/Principal Findings

We conducted a comprehensive literature search in PubMed-Medline, Scopus, Web of Science and Cochrane Library for RCTs evaluating the efficacy of 5-NI vs. control (placebo or active treatment) on parasitological cure in patients with parasitologically-demonstrated giardiasis. The search was performed in May 2013 with no language restriction by two authors independently. The efficacy outcome was parasitological cure, and harmful outcomes were abdominal pain, bitter or metallic taste, and headache. We included 30 RCTs (n = 3,930). There was a significant and slightly higher response rate with 5-NI in giardiasis treatment (RR 1.06, 95%CI 1.02–1.11, p = 0.005). There was high heterogeneity among studies (I² = 72%). The response rates for metronidazole, tinidazole and secnidazole were similar (RR 1.05, 95%CI 1.01–1.09, p = 0.01; RR 1.32 95%CI 1.10–1.59, p = 0.003; and RR 1.18 95%CI 0.93–1.449, p = 0.18, respectively). On subgroup analyses, the response rates did not vary substantially and high heterogeneity persisted (I² = 57%–80%). Harmful outcomes were uncommon, and 5-NIs were associated with lower risk of abdominal pain, and higher risk of both bitter or metallic taste and headache.

Conclusions

Studies investigating the efficacy of 5-NI in giardiasis treatment are highly heterogeneous. 5-NIs have a slightly better efficacy and worse profile for mild harmful outcomes in the treatment of giardiasis in comparison to controls. Larger high quality RCTs are needed to further assess efficacy and safety profiles of 5-NI.

Giardiasis is a major diarrheal disease with worldwide distribution. 5-nitroimidazoles, which include metronidazole and tinidazole, are the most commonly used drugs in the treatment of giardiasis. In recent years, many other drugs with variable efficacies and adverse effects have been proposed for the treatment of giardiasis. No systematic review has evaluated efficacy of 5-nitroimidazoles as a group in comparison to the other antigiardial drugs. In this context, we performed a systematic review of the literature to identify randomized controlled trials comparing the efficacies of 5-nitroimidazoles with a control drug with the aim of assessing effectiveness of 5-nitroimidazoles in the treatment of giardiasis. Four research databases were searched; 30 trials with 3,930 subjects met our inclusion criteria. Results show that there was a high variation of study outcomes between included studies. 5-nitroimidazoles were associated with higher giardiasis cure rates than controls; also, 5-nitroimidazoles are associated with lower risk of abdominal pain, and higher risks of bitter or metallic taste and headache than controls.

Management of protozoa-related diarrhea in HIV infection

Protozoa infections are an important cause of chronic diarrhea in patients infected with HIV. The introduction of highly active antiretroviral treatment to the management of HIV in the mid 1990s has led to a dramatic reduction in the incidence of these opportunistic infections in Europe and America. In contrast, in the developing world where such treatments are not readily affordable, protozoa-related diarrhea remains a major cause of morbidity and mortality in HIV-infected individuals. In this review, the optimum investigations required to diagnose these pathogens in HIV-related diarrhea, as well as current treatment options, will be discussed.

The principal conductance in Giardia lamblia trophozoites possesses functional properties similar to the mammalian ClC-2 current

The human intestinal pathogen Giardia lamblia is a flagellated unicellular protozoan with pronounced medical and biological relevance. However, the basic physiology of Giardia trophozoites has been sparsely studied, especially the electrical and ionic properties of their cellular membrane which are virtually unknown. In this study, we were able to record and characterize the macroscopic ionic currents of Giardia trophozoite membrane by electrophysiological methods of the patch clamp technique. Giardia trophozoites showed a high current density (∼600 pA/pF at -140 mV) that was activated upon hyperpolarization. This current was carried by a chloride-selective channel (I Cl-G) and it was the most important determinant of the membrane potential in Giardia trophozoites. Moreover, this conductance was able to carry other halide anions and the sequence of permeability was Br(-) > Cl(-) ≈ I(-) ≫ F(-). Besides the voltage-dependent inward-rectifying nature of I Cl-G, its activation and deactivation kinetics were comparable to those observed in ClC-2 channels. Extracellular pH modified the voltage-dependent properties of I Cl-G, shifting the activation curve from a V 1/2 = -79 ± 1 mV (pH 7.4) to -93 ± 2 mV (pH 8.4) and -112 ± 2 mV (pH 5.4). Furthermore, the maximal amplitude of I Cl-G measured at -100 mV showed dependence to external pH in a bell-shaped fashion reported only for ClC-2 channels. Therefore, our results suggest that I Cl-G possesses several functional properties similar to the mammalian ClC-2 channels.

Efficacy of nitazoxanide against clinical isolates of Mycobacterium tuberculosis

Nitazoxanide (NTZ) has bactericidal activity against the H37Rv laboratory strain of Mycobacterium tuberculosis with a MIC of 16 μg/ml. However, its efficacy against clinical isolates of M. tuberculosis has not been determined. We found that NTZ's MIC against 50 clinical isolates ranged from 12 to 28 μg/ml with a median of 16 μg/ml and was unaffected by resistance to first- or second-line antituberculosis drugs or a diversity of spoligotypes.

Prevalence of intestinal protozoa infection among school-aged children on Pemba Island, Tanzania, and effect of single-dose albendazole, nitazoxanide and albendazole-nitazoxanide

Background

Pathogenic intestinal protozoa infections are common in school-aged children in the developing world and they are frequently associated with malabsorption syndromes and gastrointestinal morbidity. Since diagnosis of these parasites is difficult, prevalence data on intestinal protozoa is scarce.

Methods

We collected two stool samples from school-aged children on Pemba Island, Tanzania, as part of a randomized controlled trial before and 3 weeks after treatment with (i) single-dose albendazole (400 mg); (ii) single-dose nitazoxanide (1,000 mg); (iii) nitazoxanide-albendazole combination (1,000 mg–400 mg), with each drug given separately on two consecutive days; and (iv) placebo. Formalin-fixed stool samples were examined for the presence of intestinal protozoa using an ether-concentration method to determine the prevalence and estimate cure rates (CRs).

Results

Almost half (48.7%) of the children were diagnosed with at least one of the (potentially) pathogenic protozoa Giardia intestinalis, Entamoeba histolytica/E. dispar and Blastocystis hominis. Observed CRs were high for all treatment arms, including placebo. Nitazoxanide showed a significant effect compared to placebo against the non-pathogenic protozoon Entamoeba coli.

Conclusions

Intestinal protozoa infections might be of substantial health relevance even in settings where they are not considered as a health problem. Examination of a single stool sample with the ether-concentration method lacks sensitivity for the diagnosis of intestinal protozoa, and hence, care is indicated when interpreting prevalence estimates and treatment effects.

Drugs for treating giardiasis

BACKGROUND

Giardiasis infection may be asymptomatic, or can cause diarrhoea (sometimes severe), weight loss, malabsorption, and, in children, failure to thrive. It is usually treated with metronidazole given three times daily for five to 10 days.

OBJECTIVES

To evaluate the relative effectiveness of alternative antibiotic regimens for treating adults or children with symptomatic giardiasis.

SEARCH METHODS

We searched the Cochrane Infectious Disease Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 6 2012); MEDLINE, EMBASE, LILACS and the International Clinical Trials Registry Platform Search Portal (3 July 2012).

SELECTION CRITERIA

We included randomized controlled trials (RCT) comparing metronidazole administered for five to 10 days with any of the following drugs: metronidazole (single dose), tinidazole, albendazole, mebendazole, and nitazoxanide. The primary outcomes were parasitological and clinical cure.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion, performed the risk of bias assessment, and extracted data. We summarized data using risk ratios and mean differences and we presented the results in forest plots and performed meta-analyses where possible. We assessed heterogeneity using the Chi(2) test, I(2) statistic and visual inspection; and we explored this by using subgroup analyses.We assessed the quality of evidence by using the GRADE approach.

MAIN RESULTS

We included 19 trials, involving 1817 participants, of which 1441 were children. Studies were generally small, with poor methods reporting. . Most reported parasitological outcomes rather than clinical improvement.Ten trials, from India, Mexico, Peru, Iran, Cuba, and Turkey, compared albendazole (400 mg once daily for five to 10 days) with metronidazole (250 mg to 500 mg three times daily for five to 10 days). This once-daily regimen of albendazole is probably equivalent to metronidazole at achieving parasitological cure (RR 0.99, 95% CI 0.95 to 1.03; 932 participants, 10 trials; moderate quality evidence), and improving symptoms (RR 0.98, 95% confidence interval (CI) 0.93 to 1.04; 483 participants, five trials; moderate quality evidence), but the duration of follow-up was short (two to three weeks). Albendazole probably has fewer side effects than metronidazole (gastrointestinal side effects: RR 0.29, 95% CI 0.13 to 0.63; 717 participants, eight trials; moderate quality evidence; neurological side effects: RR 0.34, 95% CI 0.18 to 0.64; 453 participants, five trials; low quality evidence).Five trials from Turkey, Spain and the UK compared mebendazole (200 mg three times daily for five to 10 days) with metronidazole (5 mg/kg (or 250 mg) three times daily for five to 10 days). These trials were small in size, and at high risk of bias. Consequently, reliable conclusions on the relative effectiveness cannot be made (very low quality evidence).Five further trials, from Iran, Spain and Peru, have evaluated shortened regimens of tinidazole (single dose; 179 participants, three trials), metronidazole (single dose; 55 participants, one trial), and nitazoxanide (three days; 55 participants, one trial). Again, these trials were at high risk of bias and too small to reliably detect or exclude important differences (very low quality evidence).

AUTHORS' CONCLUSIONS

Albendazole may be of similar effectiveness to metronidazole, may have fewer side effects, and has the advantage of a simplified regimen. Large, high quality trials, assessing clinical outcomes (such as diarrhoea) will help assess further alternatives.

Nitazoxanide for the empiric treatment of pediatric infectious diarrhea

We conducted a double-blind, placebo-controlled clinical trial to demonstrate the efficacy of nitazoxanide suspension for the treatment of presumed infectious diarrhea in children. Eligible patients must have had diarrheal illness lasting 3-29 days. Patients were randomized to receive either nitazoxanide or placebo twice daily for three days. The primary endpoint was time from first dose to resolution of symptoms. One hundred children mean age 3.3 years were enrolled. The median time to resolution of symptoms for nitazoxanide treated patients was 23 hours (IQR 4-48 hours) vs 103.5 hours (IQR 63->168 hours) for placebo (p<0.001). An analysis by disease subset indicated nitazoxanide treated patients had statistically shorter durations of diarrheal illness associated with Giardia lamblia (n=32, p<0.001) and those with no identified enteropathogen (n=38, p=0.008), when compared to placebo. The study medication was well tolerated. Overall, nitazoxanide was effective at reducing the duration of diarrheal illness associated with multiple etiologies, including patients with no identified enteropathogen. These results suggest nitazoxanide may be a viable therapeutic option for the empiric treatment of diarrheal illness in children where the etiology is unknown or presumed to be of infectious origin. Clinical trial registry number NCT01326338.

Hospitalization of Cuban children for giardiasis: a retrospective study in a paediatric hospital in Havana

The medical records of the 185 children who, in 2007, were admitted to the Academic Paediatric Hospital 'Centro Habana', in the Cuban capital of Havana, because of giardiasis were analysed retrospectively. A standardized form was used to collect data on the socio-demographic characteristics, clinical features, laboratory diagnosis, treatment and length of stay of each child. Information on the 15 children who had incomplete medical records was excluded from the data analysis. Of the remaining 170 children, 85 (50·0%) were aged 1-4 years, 97 (57·1%) were male, and 106 (62·4%), 92 (54·1%) and 69 (40·6%) had presented with diarrhoea, vomiting, and/or abdominal pain, respectively. Most (91·2%) of the cases had been diagnosed by the microscopical examination of a duodenal aspirate, and the drugs that had been most used frequently were quinacrine and tinidazole, which had been given to 72 (42·4%) and 62 (36·5%) of the cases, respectively. The mean length of hospital stay was 4·9 days. Such information on the clinical characteristics of giardiasis among children living in an endemic area may be valuable to paediatricians and public-health officials who wish to screen for the disease.

Future novel therapeutic agents for Clostridium difficile infection

IMPORTANCE OF THE FIELD

Clostridium difficile is the most important definable cause of healthcare acquired diarrhea. The increasing incidence and mortality associated with this enteric pathogen and the significant rate of treatment failures and recurrences with current antibiotics emphasize the need for the discovery of new and improved therapeutic and preventative agents.

WHAT THE READER WILL GAIN

We review upcoming novel therapeutic agents and the clinical evidence to support their efficacy in treating C. difficile infection. We also provide an extensive comparison of antimicrobial susceptibilities of C. difficile based on in vitro susceptibilities published in the literature.

AREAS COVERED IN THIS REVIEW

This review was conducted by a thorough examination of the public sources, including journals and scientific meeting abstracts, up to February 2009.

TAKE HOME MESSAGE

A number of new therapeutic agents are in development and being tested in clinical trials. However, high costs and concerns for resistance may limit the use of these antimicrobials for the treatment of C. difficile infection. Passive and active immunotherapy may have important future roles as therapeutic and preventative strategies for C. difficile infection.

Thiazolides: a new class of antiviral drugs

BACKGROUND

Thiazolides have emerged as a new class of broad-spectrum antiviral drugs, and the first thiazolide, nitazoxanide, is in late-stage clinical trials for treating chronic hepatitis C.

OBJECTIVE

To review the chemistry, pharmacology, toxicology and efficacy of thiazolides as antiviral agents with emphasis on clinical development of nitazoxanide in treating chronic hepatitis C.

METHODS

Literature search, information from Romark Laboratories and my personal experience with the discovery and development of thiazolides serve as the sources for this review.

CONCLUSIONS

Thiazolides are metabolically stable, highly bound to plasma proteins and are associated with a favorable toxicology profile. Phase II clinical trials have demonstrated efficacy and safety of nitazoxanide added to peginterferon with or without ribavirin in treating patients with chronic hepatitis C. More limited clinical data indicated potential in treating chronic hepatitis B, and three randomized controlled trials have demonstrated efficacy in reducing the duration of viral gastroenteritis. New generation thiazolides with the nitro group of nitazoxanide replaced by a non-reducible group are not active against anaerobes but retain broad-spectrum activity against viruses. Further studies are needed. Research indicates that these drugs may play an important and complementary role in combination with other classes of antiviral drugs.

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.

The treatment of giardiasis in children: single-dose tinidazole compared with 3 days of nitazoxanide

Giardia lamblia is among the commonest intestinal protozoa world-wide and may cause significant morbidity, especially in children. Although 5-nitroimidazole compounds have formed the mainstay of giardiasis treatment for several years, the increasing number of reports of refractory cases given these and other antigiardial agents has raised concern and led to a search for other compounds. The aim of the present study was to compare the efficacy and safety, in the treatment of children infected with G. lamblia, of nitazoxanide, given at a dose of 7.5 mg/kg twice a day for 3 days, with those of tinidazole, given as a single dose of 50 mg/kg. Overall, 166 children, each proven to be infected with G. lamblia by the microscopical examination of a faecal sample, were included in the open and randomized trial, each being allocated to receive nitazoxanide or tinidazole. The parents of each treated child were asked to collect two faecal samples from the child between 5 and 10 days after the completion of treatment, for the parasitological follow-up. Only if no G. lamblia were found in both post-treatment samples from a child was that child considered cured. Among the 137 children who completed the study (74 given nitazoxanide and 63 given tinidazole), the frequency of parasitological cure following a single dose of tinidazole was significantly higher than that following six doses of nitazoxanide (90.5% v. 78.4%; P<0.05). Both treatment schedules were well accepted and well tolerated, with only mild, transient and self-limited side-effects reported. The commonest symptom on enrolment, diarrhoea, generally cleared 2-6 days after the initiation of treatment. Although apparently less efficacious than tinidazole, nitazoxanide remains a good candidate for the treatment of children with G. lamblia infection.

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, tizoxanide and other thiazolides are potent inhibitors of hepatitis B virus and hepatitis C virus replication

Nitazoxanide (NTZ), a thiazolide anti-infective, is active against anaerobic bacteria, protozoa, and a range of viruses in cell culture models, and is currently in phase II clinical development for treating chronic hepatitis C. In this report, we characterize the activities of NTZ and its active metabolite, tizoxanide (TIZ), along with other thiazolides against hepatitis B virus (HBV) and hepatitis C virus (HCV) replication in standard antiviral assays. NTZ and TIZ exhibited potent inhibition of both HBV and HCV replication. NTZ was equally effective at inhibiting replication of lamivudine (LMV) and adefovir dipovoxil (ADV)-resistant HBV mutants and against 2'-C-methyl cytidine (2'CmeC) and telaprevir (VX-950)-resistant HCV mutants. NTZ displayed synergistic interactions with LMV or ADV against HBV, and with recombinant interferon alpha-2b (IFN) or 2'CmeC against HCV. Pre-treatment of HCV replicon-containing cells with NTZ potentiated the effect of subsequent treatment with NTZ plus IFN, but not NTZ plus 2'CmeC. NTZ induced reductions in several HBV proteins (HBsAg, HBeAg, HBcAg) produced by 2.2.15 cells, but did not affect HBV RNA transcription. NTZ, TIZ, and other thiazolides are promising new antiviral agents that may enhance current or future anti-hepatitis therapies.

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.

Giardiasis: a pharmacotherapy review

Giardia lamblia, the cause of human giardiasis, is among the most common intestinal protozoa worldwide. Human infection may range from asymptomatic shedding of giardial cysts to symptomatic giardiasis, being responsible for abdominal cramps, nausea, acute or chronic diarrhoea, with malabsorption and failure of children to thrive. At present, treatment options include the nitroimidazoles derivatives; especially metronidazole, which has been the mainstay of treatment for decades and is still widely used. The increasing number of reports of refractory cases with this group of drugs and other antigiardial agents, has raised concern and led to a search for other compounds, some of which have arisen due to the introduction of drugs initially addressed to other diseases. The present article examines some of the most important points of antigiardial pharmacotherapy available at present and the future prospects of development of new agents.

Nitazoxanide in the treatment of amoebiasis

Amoebiasis is a significant cause of morbidity worldwide and is the third leading cause of death from parasitic diseases. This study evaluated nitazoxanide, a thiazolide anti-infective, in the treatment of intestinal and hepatic amoebiasis. Prospective, randomised, double-blind, placebo-controlled studies were conducted in outpatients with intestinal amoebiasis from the Nile Delta of Egypt. Nitazoxanide was administered twice daily for 3 days at doses of 500mg (age > or =12 years), 200mg (age 4-11 years) or 100mg (age 1-3 years). Seventeen adults hospitalised with hepatic amoebiasis were treated with 500mg nitazoxanide twice daily for 10 days. Four days after completion of therapy, 32 (94%) of 34 nitazoxanide-treated patients with intestinal amoebiasis resolved symptoms compared with 15 (50%) of 30 patients who received placebo (P<0.001). Thirty-two (94%) of 34 nitazoxanide-treated patients were free of Entamoeba histolytica in two post-treatment stool specimens compared with only 13 (43%) of 30 patients receiving placebo (P<0.0001). All patients with hepatic amoebiasis responded to nitazoxanide therapy. Nitazoxanide is effective in treating invasive intestinal amoebiasis and in eliminating E. histolytica colonisation of the intestinal tract. Further studies are warranted in patients with hepatic amoebiasis.

WITHDRAWN: Drugs for treating giardiasis

BACKGROUND

There can be a high rate of recurrence of disease after initial drug treatment for giardiasis. These drugs also have a range of adverse effects.

OBJECTIVES

The objective of this review was to assess the effects of drug treatments for giardiasis.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, EMBASE, Current Contents, and reference lists of articles.

SELECTION CRITERIA

Randomised and quasi-randomised trials of drug therapy for giardiasis compared with placebo or another drug.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Thirty-four trials were included. Only one trial was without serious methodological flaws. Compared with placebo, drug treatment was associated with an improved cure rate (odds ratio 11.51, 95% confidence interval 2.29 to 57.98). Metronidazole treatment longer than three days had a better parasitological cure rate than other long treatment courses (odds ratio 2.41, 95% confidence interval 1.31 to 4.44), but there was significant heterogeneity between the trials. Available evidence has not detected a difference in cure between single dose therapy and longer treatment courses (odds ratio 0.33, 95% confidence interval 0.08 to 1.34). Within the single dose regimens, the available evidence did not demonstrate a difference in parasitological cure rate between tinidazole and other short therapies (odds ratio 3.39, 95% confidence interval 0.95 to 12.04), but had a higher clinical cure rate (odds ratio 5.33, 95% 2.66 to 10.67).

AUTHORS' CONCLUSIONS

A single dose of tinidazole appears to give the highest clinical cure rate for giardiasis with relatively few adverse effects.

Nitazoxanide in the treatment of Ascaris lumbricoides in a rural zone of Colima, Mexico

Intestinal parasites in Mexico are an endemic problem. A study was conducted in children, teenagers and adults in a rural community in Colima, Mexico to examine the prevalence and intensity of Ascaris lumbricoides infection and to evaluate the parasitological and clinical efficacy of nitazoxanide (NTZ). Two hundred and eighty children, teenagers and adults participated in this study. Parasitological diagnosis from faeces was confirmed by three consecutive stool samples using the floatation concentration Faust method. Egg counts were performed as described by the Kato-Katz technique before and after treatment. A questionnaire was systematically applied to obtain information about socio-economic status and hygienic habits. One hundred and six participants (38%) were diagnosed as harbouring intestinal parasites, and 86 of them (81%) were infected with A. lumbricoides. All patients with ascariasis infections underwent a complete physical examination before and after NTZ treatment. NTZ resolved 88% of the ascariasis cases, with a 89% clinical efficacy, and there was a 97.5% reduction in the levels of morbidity. The most intense infections for A. lumbricoides were found in housewives, and statistically significant associations were found between ascariasis and the absence of drainage and living in houses with dirt floors.

Nitazoxanide in the treatment of viral gastroenteritis: a randomized double-blind placebo-controlled clinical trial

BACKGROUND

Enteric viruses including noroviruses and rotavirus are leading causes of diarrhoeal disease and gastroenteritis worldwide, and there is no effective treatment.

AIM

To evaluate nitazoxanide, a thiazolide anti-infective agent, in treating viral gastroenteritis in adults and adolescents.

METHODS

50 out-patients at least 12 years of age (mean 33.5 years) presenting with diarrhoea and stool-positive by enzyme-linked immunosorbent assay for norovirus, rotavirus or adenovirus were enrolled in a double-blind, placebo-controlled clinical trial. Patients were randomly assigned either nitazoxanide 500 mg or placebo twice daily for 3 days. The primary end point was time from first dose to resolution of symptoms. Analysis was modified intent-to-treat for 45 patients, excluding five patients with other identified enteropathogens at baseline.

RESULTS

The median time from first dose to resolution of symptoms was 1.5 days (IQR: 0.5-2.5) for nitazoxanide-treated patients and 2.5 days (IQR: 1.5-4.5) for the placebo group. Significant reductions in time to resolution of symptoms were observed for all patients analysed (P < 0.0001) and for subsets of patients with rotavirus (P = 0.0052) and norovirus (P = 0.0295). The number of patients with adenovirus (n = 5) was too small to draw any conclusion. No significant adverse events were reported.

CONCLUSIONS

Nitazoxanide may play an important role in managing viral gastroenteritis in adults.

Treatment options for the eradication of intestinal protozoa

Pathogenic intestinal protozoa are responsible for clinically important infections in both the developed and the developing world. These organisms are responsible for both acute and chronic diarrhea, and Entamoeba histolytica, which affects the colon, can spread to involve the liver. Many of these pathogens, particularly the intracellular protozoa that predominantly affect the small intestine, produce their most devastating effects in patients with HIV/AIDS and other forms of immune deficiency. There are also various intestinal protozoa that do not seem to have any adverse effects on humans and can, therefore, be regarded as harmless commensal organisms. Although treatment has been available for several decades for giardiasis, isosporiasis and amoebiasis, until recently there have been no effective remedies for infection with intestinal coccidia--Cryptosporidium, Microsporidium and Cyclospora species. Cyclospora respond well to co-trimoxazole, microsporidia respond variably to albendazole, and cryptosporidia can often be eradicated by nitazoxanide. In chronically infected HIV-positive patients, treatment with multidrug regimens usually results in rapid resolution of the diarrhea and, in many instances, eradication of the parasite.

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.

Cytotoxic effect of curcumin on Giardia lamblia trophozoites

Giardia lamblia is one of the most important worldwide causes of intestinal infections produced by protozoa. Thus, the search for new alternative therapeutic approaches for this parasitic disease is very important. Common drugs used to control and eradicate this infection, frequently exhibit side effects that force patients to abandon treatment. The present work evaluates the anti-protozoan activity of curcumin, the main constituent of turmeric. Axenic G. lamblia (Portland 1 strain) cultures were exposed to different concentrations of curcumin. Its effects were evaluated on parasite growth, adhesion capacity and parasite morphology. We also evaluated the capacity of curcumin to induce an apoptosis-like effect. All curcumin concentrations inhibited trophozoite growth and adhesion in more than 50% in dose and time dependent manner. Morphological changes were described as protrusions formed under the cytoplasmic membrane, deformation due to swelling and cell agglutination. Curcumin induced apoptosis-like nuclear staining in dose and time dependent manner. In conclusion, curcumin exhibited a cytotoxic effect in G. lamblia inhibiting the parasite growth and adherent capacity, induced morphological alterations, provoked apoptosis-like changes. Future in vitro and in vivo experiments are endowed to elucidate the effect of curcumin in an experimental model of G. lamblia infection, analyze the involvement of ion channels in the swelling effect of curcumin during an apparent osmotic deregulation in G. lamblia trophozoites. This will lead to the proposal of the action mechanism of curcumin as well as the description of mechanism involved during the activation process for the apoptotic-like effect.