Thiazolides: a new class of antiviral drugs.
ABSTRACT 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.
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.
Literature search, information from Romark Laboratories and my personal experience with the discovery and development of thiazolides serve as the sources for this review.
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.
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ABSTRACT: The aim of this study was to evaluate the efficacy of nitazoxanide for the treatment of diarrhea and enteritis caused by Cryptosporidium species in patients 12 years of age and older. A multicenter, randomized, double-blind, placebo-controlled study was conducted in 90 outpatients 12 years of age and older from the Nile Delta region of Egypt. Patients were randomized to receive either one 500 mg tablet or one matching placebo tablet, or 25 mL of nitazoxanide oral suspension (500 mg nitazoxanide), each given twice daily for 3 days. Clinical and microbiologic response rates were evaluated 4 days after completion of treatment. Twenty-seven (96%) of the 28 patients receiving nitazoxanide tablets responded clinically compared with 11 (41%) of 27 patients who received placebo (P < .0001). Twenty-six (93%) of the 28 patients who received nitazoxanide were free of Cryptosporidium oocysts in each of 2 posttreatment stool samples compared with only 10 (37%) of 27 patients who received placebo (P < .0001). Response rates in patients receiving the tablets and the suspension were comparable (clinical response rate for suspension, 27 of 31 [87%]; microbiologic response rate for suspension, 28 of 31 [90%]). These findings show that a 3-day course of nitazoxanide is effective in treating diarrhea and enteritis caused by Cryptosporidium in nonimmunodeficient patients 12 years of age and older.Clinical Gastroenterology and Hepatology 04/2006; 4(3):320-4. · 6.65 Impact Factor
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ABSTRACT: The effects of nitazoxanide on warfarin pharmacokinetics and pharmacodynamics are examined. This was a Phase I, single-center, open-label, randomized, two-way, crossover study. Secondary endpoints included an evaluation of the effect of nitazoxanide on coagulation parameters observed after a single dose of warfarin and an assessment of the overall tolerability of study treatments. Fourteen healthy men were selected for the study. The study consisted of two treatment periods (Treatment A and Treatment B), each lasting 6 days, with a washout period of at least 21 days between both warfarin intakes. All subjects were scheduled to receive both Treatment A and Treatment B, according to the randomization list. Treatment A consisted of a single oral dose of 25 mg warfarin sodium (five 5-mg tablets). Treatment B consisted of a single oral intake of 25 mg warfarin sodium (five 5-mg tablets) and one 500-mg tablet of nitazoxanide (with nitazoxanide 500 mg continued twice daily for up to 6 days). All 14 subjects received Treatment B, and 13 of the 14 subjects received Treatment A. Pharmacokinetic results were similar in both treatments, and pharmacodynamic parameters were similar in both treatments. Fourteen adverse events occurred in eight subjects after administration of at least one dose of the study drug. Eleven adverse events occurred in six subjects after treatment with warfarin and nitazoxanide, and three adverse events occurred in two subjects after treatment with warfarin alone. At discharge, a high hemoglobin level and a low total bilirubin level were reported in both groups. Coadministration of nitazoxanide twice daily for six days did not affect the pharmacokinetic or pharmacodynamic properties of a single 25-mg dose of warfarin sodium. Administration of a single dose of warfarin or combined administration of a single dose of warfarin and multiple doses of nitazoxanide appeared safe and well tolerated.American journal of health-system pharmacy: AJHP: official journal of the American Society of Health-System Pharmacists 06/2009; 66(9):838-42. · 2.10 Impact Factor
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ABSTRACT: Sustained virologic response (SVR) rates of 50%-60% have been achieved in patients with chronic hepatitis C genotype 4 treated with peginterferon plus ribavirin. The safety and efficacy of nitazoxanide plus peginterferon alfa-2a, with or without ribavirin, were evaluated in a randomized controlled trial at 2 centers in Egypt. Previously untreated patients with chronic hepatitis C and genotype 4 infection were assigned randomly to groups that were given standard of care (peginterferon alfa-2a and ribavirin for 48 weeks, n = 40), nitazoxanide monotherapy for 12 weeks followed by nitazoxanide plus peginterferon alfa-2a for 36 weeks (n = 28), or nitazoxanide monotherapy for 12 weeks followed by nitazoxanide plus peginterferon alfa-2a and ribavirin for 36 weeks (n = 28). Therapeutics included nitazoxanide (500 mg) twice daily, peginterferon alfa-2a (180 microg) once weekly, and weight-based ribavirin (1000-1200 mg/day). The percentages of rapid virologic response (RVR), defined as undetectable HCV RNA at week 4 of combination therapy, and SVR were significantly higher in patients given the triple therapy compared with the standard of care (64% vs 38%, P = .048; and 79% vs 50%, P = .023; respectively). Patients given nitazoxanide plus peginterferon alfa-2a had intermediate rates of RVR (54%) and SVR (61%). Adverse events were similar across treatment groups except for higher rates of anemia in the groups receiving ribavirin. The combination of nitazoxanide, peginterferon alfa-2a, and ribavirin increased the percentages of patients with RVR and SVR, compared with patients given peginterferon plus ribavirin, without an increase in adverse events.Gastroenterology 12/2008; 136(3):856-62. · 12.82 Impact Factor