In vitro efficacy of nitro- and halogeno-thiazolide/thiadiazolide derivatives against Sarcocystis neurona

Sarcocystis neurona is an obligate intracellular parasite that causes equine protozoal myeloencephalitis (EPM). The aim of this work was to document inhibitory activities of nitazoxanide (NTZ, [2-acetolyloxy-N-(5-nitro 2-thiazolyl) benzamide]) and new thiazolides/thiadiazolides on S. neurona in vitro development, and investigate their structure-activity relationships. S. neurona was grown in bovine turbinate cell cultures. At concentrations varying from 1.0 to 5.0mg/L, nitazoxanide and 21 of 32 second generation thiazolide/thiadiazolide agents exerted a > or =95% maximum inhibition on S. neurona development. Most active agents were either NO(2) or halogen substituted in position 5 of their thiazole moiety. In contrast, other 5-substitutions such as hydrogen, methyl, SO(2)CH(3), and CH(3) negatively impacted activity. Compared with derivatives with an acetylated benzene moiety, deacetylated compounds which most probably represent primary metabolites exhibited similar inhibitory activities. Present data provide the first evidence of in vitro inhibitory activities of nitazoxanide and new thiazolides/thiadiazolides on S. neurona development. Active halogeno-thiazolide/thiadiazolides may provide a valuable nitro-free alternative to nitazoxanide for EPM treatment depending on further evaluation of their in vivo activities.

Clinical trial: randomized, double-blind, placebo-controlled study of nitazoxanide monotherapy for the treatment of patients with chronic hepatitis C genotype 4

BACKGROUND

Nitazoxanide, licensed in the US for treatment of Cryptosporidium parvum and Giardia lamblia, inhibits hepatitis C virus replication in replicon systems.

AIM

To evaluate the safety and efficacy of nitazoxanide monotherapy for the treatment of chronic hepatitis C.

METHODS

This multicentre, randomized, double-blind, placebo-controlled study randomized 50 adult patients with chronic hepatitis C genotype 4 at three centres in Egypt to nitazoxanide 500 mg tablet or placebo twice daily for 24 weeks. Patients were followed up every 4 weeks during treatment and for 24 weeks after therapy.

RESULTS

Seven of 23 patients (30.4%) in the nitazoxanide group achieved undetectable serum HCV RNA compared to 0 of 24 in the placebo group during therapy (P = 0.004). Each of the seven responders had baseline HCV RNA levels < or =400 000 IU/mL. Six of the seven virological responders were followed up for 24 weeks after the end of treatment, and four patients (17.4% of 23 treated) had a sustained virological response. Adverse events were similar in the nitazoxanide and placebo groups.

CONCLUSION

Nitazoxanide monotherapy is safe and effective in achieving sustained virological response in a modest number of patients with chronic hepatitis C genotype 4, particularly in patients with low baseline serum HCV RNA levels.

Double-blind, randomized, placebo-controlled study of nitazoxanide in the treatment of fascioliasis in adults and children from northern Peru

BACKGROUND

Human fascioliasis is a significant world-wide health problem, and massive or repeated infections by Fasciola hepatica can lead to considerable morbidity.

AIM

: To evaluate the safety and efficacy of nitazoxanide, when compared with placebo, in the treatment of fascioliasis in adults and children from northern Peru.

METHODS

A double-blind, placebo-controlled study was carried out in 50 adults and 50 children infected with F. hepatica. The diagnosis of infection was based on the presence of F. hepatica eggs in one stool sample obtained before inclusion in the study. Patients were randomized to receive treatment with either a 7-day course of nitazoxanide (100 mg b.d., age range 2-3 years; 200 mg b.d., age range 4-11 years; 500 mg b.d., age > 12 years) or matching placebo. Three post-treatment stool examinations were carried out between 30 and 90 days after initiation of treatment.

RESULTS

The parasite was eliminated in 18 of 30 (60%) adults completing the study who received nitazoxanide vs. one of eight adults in the placebo group (P = 0.042), and similarly in 14 of 35 (40%) children completing the treatment vs. none of eight in the placebo group (P = 0.038). Only mild, transient adverse events were reported.

CONCLUSIONS

A 7-day course of nitazoxanide was effective in adults and children in the treatment of F. hepatica, when compared with placebo.

Treatment of diarrhea caused by Giardia intestinalis and Entamoeba histolytica or E. dispar: a randomized, double-blind, placebo-controlled study of nitazoxanide

A prospective randomized, double-blind, placebo-controlled study was conducted to assess the efficacy and safety of nitazoxanide in the treatment of diarrhea caused by Giardia intestinalis or Entamoeba histolytica and/or E. dispar in 89 adults and adolescents, 22 of whom were diagnosed with G. intestinalis, 53 with E. histolytica and/or E. dispar, and 14 with both G. intestinalis and E. histolytica and/or E. dispar. The study medication was administered as 1 nitazoxanide 500-mg tablet or a matching placebo twice daily for 3 days. Thirty-eight (81%) of 47 patients in the nitazoxanide treatment group resolved diarrhea within 7 days (median, 3 days) after initiation of treatment, versus 17 (40%) of 42 in the placebo group (P=.0002). With its efficacy in treating a broad spectrum of enteric protozoan pathogens, nitazoxanide could play an important role in the management of diarrhea caused by enteric protozoa, reducing morbidity and costs associated with these diarrheal illnesses.

Treatment of diarrhea caused by Cryptosporidium parvum: a prospective randomized, double-blind, placebo-controlled study of Nitazoxanide

A prospective randomized, double-blind, placebo-controlled study was conducted in 50 adults and 50 children from the Nile delta of Egypt, to evaluate the efficacy of nitazoxanide in treating diarrhea caused by Cryptosporidium parvum. Nitazoxanide was administered in 500-mg doses twice daily for 3 days in adults and adolescents, in 200-mg doses twice daily for 3 days in children aged 4-11 years, and in 100-mg doses twice daily for 3 days in children aged 1-3 years. At 7 days after initiation of therapy, diarrhea had resolved in 39 (80%) of the 49 patients in the nitazoxanide treatment group, compared with 20 (41%) of 49 in the placebo group (P<.0001). Diarrhea was resolved in most patients receiving nitazoxanide within 3 or 4 days of treatment initiation. Nitazoxanide treatment reduced the duration of both diarrhea (P<.0001) and oocyst shedding (P<.0001).

Cryptosporidiosis in Benha, study of some recent modalities in diagnosis and treatment

A total prevalence of cryptosporidiosis was carried out on 1087 diarrheal patients of all age groups attending the outpatient clinics using modified Ziehl-Neelsen stain (MZN) and Meriflour direct immunofluorescent technique (IFA). IFA was more sensitive, specific and gave positive results 19.5% than MZN stain which gave a positivity 13.5% Cases were divided into 3 groups, each group was treated by one of nitazoxanid (NTZ), or co-trimoxazole or placebo. The most effective drug was NTZ which cured 39 patients (79.6%) out of 49 patients followed by co-trimoxazole that gave cure of 20 (41.6%) out of 48 patients. Placebo cured 20 (40%) out of 50 patients.

Nitazoxanide: pharmacokinetics and metabolism in man

OBJECTIVES

Nitazoxanide (N), a new broad-spectrum parasiticidal agent, is rapidly deacetylated to tizoxanide (T). The objective of the study was to determine if metabolites other than T are present in the plasma and excreted after single dose oral administration of radiocarbon-labelled N in healthy subjects.

METHODS

Six healthy volunteers received a single 500 mg oral dose of N labelled with 2.92 MBq radiocarbon. The radioactivity in blood, plasma, urine, feces and expired air was monitored at scheduled intervals for up to 10 days. Selected samples were assayed by HPLC for T and submitted to metabolite identification by mass spectrometry. In vitro experiments were also conducted (incubation with animal and human microsomes, deacetylation kinetics). Plasma and bile samples obtained in a patient treated with N for sporozoal infection were also assayed for T.

RESULTS

Elimination of radiocarbon occurred both in the urine (31.5% of the dose on average) and in the feces (66.2% on average). T and T-glucuronide contributed 15% of total urine radioactivity. N was found to deacetylate extremely rapidly to T in plasma (half-life of about 6 minutes at 37 degrees C) as well as in presence of liver microsomes. T was the only species obtained by incubation with human microsomes while rat microsomes yielded hydroxylated T in addition. The main species identified in human plasma, urine and bile was T-glucuronide, the identification of which was confirmed by comparison with an authentic sample. No species other than T was detected in feces, indicating intensive intestinal deconjugation, while radioactivity and absorbance detectors showed largely unresolved clusters.

Nitazoxanide, a potential drug for eradication of Helicobacter pylori with no cross-resistance to metronidazole

Nitazoxanide, a thiazolide compound, and its desacetyl derivative, tizoxanide, have antimicrobial properties against anaerobic bacteria, as well as against helminths and protozoa. Because the treatment of Helicobacter pylori infection may be jeopardized by metronidazole resistance, nitazoxanide and tizoxanide were tested in vitro against these bacteria. The MICs of these two compounds were determined by agar dilution and were compared to those of metronidazole. Exposure to subinhibitory concentrations of nitazoxanide was also carried out by the method of Szybalski (W. Szybalski and V. Bryson, J. Bacteriol. 64:489-499, 1952). The MICs of nitazoxanide and tizoxanide for 103 strains ranged from 0.25 to 8 microg/ml, with the MIC at which 50% of strains are inhibited (MIC50) being 1 microg/ml and the MIC90 being 4 microg/ml, and no resistant strain was detected, whereas strains resistant to metronidazole were detected. When 10 strains were successively subcultured on medium containing nitazoxanide, no significant change in the MICs of this compound was observed. A pilot study of nitazoxanide for the treatment of H. pylori infection was carried out with 86 patients in association with 20 mg of omeprazole. An eradication rate of 83% (95% confidence interval, 64% to 94%) was obtained in a per-protocol analysis in the group receiving 1 g of nitazoxanide orally twice daily, and a few side effects were observed. The failures could not be explained by the selection of resistant strains since the MICs of nitazoxanide were similar for six pairs of isolates (proven to be the same strain by random amplified polymorphic DNA analysis in four cases) cultured before and after the treatment failure. Nitazoxanide exhibits good antimicrobial activity against H. pylori without the problem of acquired resistance which is encountered with metronidazole and has been demonstrated to have a satisfactory effect in a dose-ranging pilot study. It is therefore a good candidate to be included in treatment regimens aimed at the eradication of H. pylori.

A double-'blind' placebo-controlled study of nitazoxanide in the treatment of cryptosporidial diarrhoea in AIDS patients in Mexico

Sixty-six patients with human immunodeficiency virus infection and diarrhoea caused by Cryptosporidium parvum were enrolled in a double-'blind' placebo-controlled study to evaluate the safety and efficacy of nitazoxanide in the treatment of cryptosporidiosis related to the acquired immune deficiency syndrome. Patients were randomly assigned to one of 3 treatment groups and received either 500 mg twice daily of nitazoxanide, 1000 mg twice daily of nitazoxanide, or placebo orally for 14 d; the patients on nitazoxanide then crossed over to placebo while the placebo patients crossed over to nitazoxanide therapy at either the high or low dose depending on their randomization. Three post-treatment faecal examinations were conducted on days 15, 22 and 29 following initiation of treatment: patients were considered 'cured' if none revealed any C. parvum oocysts. Both doses of nitazoxanide produced parasitological cure rates superior to the placebo responses (12/19 [63%, P = 0.016] for patients receiving 1 g/d and 10/15 [67%, P = 0.013] for those receiving 2 g/d). Parasitological cure was correlated with the complete resolution of the diarrhoeal syndrome in 19 of the 22 treated patients who were considered parasitologically cured (86%). Both doses of nitazoxanide were well tolerated by the patients.

Parasitic gut infections

Emerging spore-forming protozoa such as cryptosporidia and microsporidia are becoming major public health problems in developing countries as well as in the developed world. They are a new addition to an already long list of intestinal parasites, but their diagnosis is much more difficult than for well-known protozoa and helminths. Fortunately, enzyme immunoassay and polymerase chain reaction techniques are becoming available not only for the detection of Cryptosporidium parvum and the microsporidia, but also for Entamoeba histolytica and Giardia lamblia. These assays are not only increasing the sensitivity of detection but are also allowing, for the first time, species differentiation such as Entamoeba histolytica/dispar or Encephalitozoon intestinalis/Enterocytozoon bieneusi.

Nitazoxanide in the treatment of cryptosporidial diarrhea and other intestinal parasitic infections associated with acquired immunodeficiency syndrome in tropical Africa

Eighteen patients hospitalized with intestinal parasitic infections associated with diarrhea and dehydration completed a study of nitazoxanide in the treatment of Cryptosporidium parvum and other intestinal parasitic infections. Seventeen of the 18 patients were positive for human immunodeficiency virus. Twelve patients were diagnosed with clinical Stage 4 acquired immunodeficiency syndrome (AIDS) according to the 1990 World Health Organization proposed clinical classification system and cryptosporidiosis. Nitazoxanide (500 mg tablets) were administered orally, one tablet twice a day for seven consecutive days. Cryptosporidium parvum oocysts were eradicated or reduced by more than 95% in seven of the 12 Stage 4 AIDS patients who completed the study based upon two post-treatment fecal examinations conducted on days 7 and 14 following the initiation of treatment. The elimination or reduction of C. parvum oocysts was associated with a complete resolution of diarrhea in four of the seven patients. The test drug was also effective against cases of Isospora belli, Entamoeba histolytica, Giardia lamblia, Ascaris lumbricoides, Enterobius vermicularis, Hymenolepis nana, and Dicrocoelium dentriticum. Treatment with nitazoxanide was well tolerated by the patients. There were no abnormalities in blood chemistry or hematology data that were considered to be attributable to nitazoxanide therapy. Transient episodes of vomiting were observed in four patients, all with Stage 4 AIDS and cryptosporidiosis, which resolved spontaneously without discontinuation of treatment and were not considered to be related to administration of nitazoxanide.

In vitro evaluation of activities of nitazoxanide and tizoxanide against anaerobes and aerobic organisms

The antibacterial activities of nitazoxanide and its main metabolite, tizoxanide, were tested against a broad range of bacteria, including anaerobes. Metronidazole, amoxicillin, amoxicillin-clavulanic acid, piperacillin, cefoxitin, imipenem, and clindamycin were used as positive controls. MICs were determined by reference agar dilution methods. The 241 anaerobes were all inhibited by nitazoxanide, with the MICs at which 90% of isolates are inhibited (MIC90S) being between 0.06 and 4 mg/liter with the exception of those for Propionibacterium species, for which the MIC90 was 16 mg/liter. The MIC90s of nitazoxanide were 0.5 mg/liter for the Bacteroides fragilis group (80 strains), 0.06 mg/liter for Clostridium difficile (21 strains), and 0.5 mg/liter for Clostridium perfringens (16 strains). Metronidazole showed a level of activity comparable to that of nitazoxanide except against Bifidobacterium species, against which it was poorly active, and Propionibacterium species, which were resistant to metronidazole. The other antibiotics showed various levels of activity against anaerobes, with imipenem along with nitazoxanide being the most active agents tested. Tizoxanide was less effective than nitazoxanide except against the B. fragilis group, against which its activity was similar to that of nitazoxanide. Under aerobic conditions, nitazoxanide demonstrated poor activity against members of the family Enterobacteriacae and Pseudomonas, Staphylococcus, and Enterococcus species. The same results were obtained when culture was performed under anaerobic conditions with the notable exception of the results against Staphylococcus aureus. The MICs of nitazoxanide were in the range of 2 to 4 mg/liter for 34 clinical isolates of S. aureus, 12 of which were methicillin resistant, while tizoxanide was not effective.

Pharmacokinetics of nitazoxanide after single oral dose administration in 6 healthy volunteers

The objective of this study was to gather first information on the time course of plasma concentrations and urinary excretion of the antiprotozoal nitazoxanide (N) and to identify potential metabolites in healthy subjects after a single oral dose of 500 mg of nitazoxanide. The clinical trial was conducted as an open single oral dose study in 6 healthy male subjects. After a standardized continental breakfast the subjects took a single oral dose of 500 mg nitazoxanide (coated tablet) with 100 ml tap water. The plasma concentration and the urinary excretion of nitazoxanide (N), desacetyl-nitazoxanide (DN), aminonitrothiazole (ANT), acetylsalicylate (AS), salicylate (S), gentisate (G) and salicylurate (SU) were monitored up to 72 h after administration. The only measurable species in plasma was DN, which reached a Cmax of 1.9 mg/l (range 1.1-2.5) 2-6 h after dosing, and an AUC of 3.9-11.3 mg x h/l. Its terminal half-life ranged from 1.03 to 1.6 h. DN was extensively bound to plasma proteins (> 97.5%). Only 8% of the dose was recovered in the urine, in the form of DN (5%), SU (3%), and traces of ANT (0.1%). In vitro N was very rapidly hydrolyzed to DN by plasma esterases.

Treatment of imported cases of falciparum malaria in France with halofantrine

Halofantrine is a 9-phenanthrenemethanol which is effective against multi-drug resistant strains of Plasmodium falciparum. It has been shown to be highly effective and extremely well tolerated in the treatment of imported cases of falciparum malaria in France. A total of 1,500 mg administered in three 500 mg doses at six-hour intervals results in a 100% cure rate in semi-immune subjects. This dosage should be repeated after 14 days to obtain the same cure rate in non-immune patients. Minor clinical side effects included epigastric pains, nausea and, in one case, a skin rash.

Ovicidal effects of albendazole in human ascariasis, ancylostomiasis and trichuriasis

Albendazole, a broad spectrum anthelmintic, was administered as a 400 mg single dose to 20 patients harbouring Ascaris (ten cases), hookworms (four cases each of Ancylostoma duodenale and Necator americanus) and trichuriasis (ten cases). Faeces were obtained before treatment and during the following five days. Coprocultures were made for 90 days for Ascaris and Trichuris eggs, hookworm eggs were cultured by the Harada-Mori technique for at least eight days. Albendazole was ovicidal against all four genera of nematodes.

Nitazoxanide in the treatment of Taenia saginata and Hymenolepis nana infections

Nitazoxanide , a nitrothiazole derivative, was tested in 22 patients infected with Taenia saginata and 18 infected with Hymenolepis nana. A single 25 mg/kg body weight dose was effective against T. saginata, while twice this dose level (50 mg/kg), also as a single dose, was required for treating H. nana infection. Tolerance of the drug was good at both dose levels used.

Benzimidazoles in the treatment of trichuriasis: a review

Treatment of severe symptomatic trichuriasis observed with heavy worm burdens is not satisfactory with recommended doses of mebendazole, flubendazole and albendazole. Higher doses of anthelmintics for longer periods of treatment generally improve the cure rates but treatment of such associated symptoms as diarrhoea is recommended before starting anthelmintic therapy. Such severe cases of trichuriasis should be considered separately; they do not represent the majority of cases infected by this parasite, which usually respond to benzimidazoles.

Albendazole: a new single dose anthelmintic. Study in 1455 patients

Albendazole has been tested in an open trial conducted in France, seven countries of West-Africa, Martinique and the People's Republic of China in a total of 1455 patients harboring single or mixed infections caused by round-worms, pinworms, hookworms and whipworms. All patients were closely observed before and after treatment for clinical side effects and hematology and clinical chemistry values were done in about 5% of the cases. Fecal samples obtained before and approximately 15, 16 and 17 days after treatment were examined using the Kato test, and when negative, a concentration technic. In case of ancylostomiasis, a coproculture was carried out for species identification. Following a single oral dose, albendazole was highly effective in enterobiasis (100%), ascariasis (89%), ancylostomiasis caused by Necator americanus (88%) and trichuriasis (70%). The drug did not procedure any significant adverse reactions or modifications of the hematological and clinical blood chemistry values and only 6% of the 1455 patients reported minor side effects.

Nitroimidazoles in the treatment of trichomoniasis, giardiasis, and amebiasis

Nitroimidazoles have been extensively evaluated in the treatment of trichomoniasis, giardiasis, liver and intestinal amebiasis. The most widely used are metronidazole, tinidazole, ornidazole, and secnidazole. Tinidazole, ornidazole, and secnidazole have a much longer half-life than metronidazole, allowing single-dose or once daily administration. Nitro-5-imidazoles remain extremely effective drugs for treating protozoans, Trichomonas vaginalis, Entamoeba histolytica, and Giardia intestinalis. Although all are suspected of potential carcinogenicity, they are the drugs of choice for treating protozoal infections.

[Pharmacokinetics and urinary metabolism of albendazole in man]

Albendazole, a new broad spectrum benzimidazole anthelmintic, has been administered in 10 male volunteers. Administration was randomized using 100 mg tablets, 200 mg tablets and a 2% suspension. Blood samples were obtained 0.5; 1; 1.5; 2; 2.5; 3; 3.5; 4; 5; 6; 8; 12; 24; 72 h after treatment. Albendazole sulfoxide, one of the mains albendazole blood metabolites, was assayed by HPLC and the blood half life was calculated as 8 1/2 h. The three different pharmaceutical formulations were considered bioequivalent. Urines were collected, and using T. L. C. Technics, main metabolites were identified and characterized. Hydrolysis of the carbamate function and oxidation of the sulfur atom, the alkyle chain and the aromatic ring were the main biotransformations observed.

Albendazole: placebo-controlled study in 870 patients with intestinal helminthiasis

A total of 870 patients, both males and females, from 3 to 79 years old, received either albendazole or a placebo for the treatment of nematode and cestode infections. Each patient was interviewed and underwent a complete physical examination on the initial visit. In addition, complete blood count, clinical blood chemistry values and routine urinalysis were performed before and at least 24 hours after the last treatment. Stool examinations were performed before, 7 and 21 days after treatment. Direct examination, an egg count using the Kato technique and faecal concentration were carried out for each patient. In ancylostomiasis and strongyloidiasis, faeces were cultured by the Harada-Mori technique. Albendazole, as a single 400 mg oral dose, was highly effective against Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale and Trichuris trichiura; efficacy against Strongyloides stercoralis was observed after three consecutive days of treatment at the same daily dose level. Efficacy against Hymenolepis nana was fair. Based on both clinical signs and biological values, albendazole did not produce any significant side effects.

[Albendazole in the treatment of strongyloidiasis. Report of 66 cases]

Albendazole, a new broad spectrum anthelmintic, has been tested in 66 adult patients infected by S. stercoralis. 77.2% cure rate was observed following 800 mg once a day for 3 consecutive days, based on repeated fecal examinations using a concentration technic (Junod) and a Baermann test, carried out during 6 to 9 months following treatment. Associated ancylostomiasis caused by N. americanus and trichuriasis were also completely cured (100%). Based on clinical side effects and laboratory investigations, the drug did not produce any significant adverse reactions.

Albendazole: a new broad spectrum anthelmintic. Double-blind multicenter clinical trial

A new anthelmintic drug, albendazole, has been tested in a multicenter double-blind placebo controlled study in 392 patients from France and West Africa in children and adults with single or mixed infections caused by roundworms, hookworms, whipworms, threadworms and tapeworms. All patients were closely observed before and after treatment for clinical side effects, hematological or clinical blood chemical changes. Fecal samples obtained before, and 7 days and 21 days after treatment were examined using a concentration technic (Ritchie), a coproculture (Harada-Mori) and an egg count (Kato). Following a single dose of 400 mg in adults, cure rates of 96% in ascaridiasis, 96% in ancylostomiasis caused by dose of 400 mg in adults, cure rates of 96% in ascaridiasis, 96% in ancylostomiasis caused by Ancylostoma duodenale, 90% in ancylostomiasis caused by Necator americanus and 76% in trichuriasis were recorded. About 48% of the patients infected by Strongyloides stercoralis were cured following administration of 400 mg per day for 3 consecutive days. The efficacy of half of the adult dose (200 mg) was much lower in children. None of the patients who received placebo were cured. The drug did not produce any significant side effects and approximately the same numbers were reported in the albendazole and the placebo groups. No variations of the hematology and clinical blood chemistry values were recorded.

[Treatment of intestinal nematode infections with albendazole. Preliminary results (author's transl)]

A randomized double-blind study, in order to evaluate effectiveness and tolerance of albendazole, was carried out in 186 african subjects presenting intestinal nematode infections in Mali and Senegal. The drug, well tolerated, given as a single dose of 0.4 g (adolescents and adults) or 0.2 g (children) is curative in more than 90% for ascariasis. For ancylostomiasis and trichuriasis, the effectiveness is less satisfactory in children, probably due to insufficient dosage in this age group.