A Phase 2 interventional study of Nitazoxanide and Placebo in Gastroenteritis Norovirus, sponsored by National Institute of Allergy and Infectious Diseases (NIAID). Completed at 12 sites in United States. Open to participants aged 12 Years to 99 Years. Per ClinicalTrials.gov, last updated 2025-05-21.
Sponsored by National Institute of Allergy and Infectious Diseases (NIAID) · Phase 2, Interventional, and Treatment
This is a phase 2 multi-center, double-blind, placebo-controlled study of the efficacy and safety of nitazoxanide for the treatment of solid organ and hematopoietic stem cell transplant recipients with symptomatic diarrhea due to Norovirus. The study involves a total of 160 Hematopoietic Stem Cell or Solid Organ transplant recipients, equal to or greater than 12 years of age with diagnosis of Norovirus who will be selected and randomly assigned (1:1) to nitazoxanide or placebo group. The study duration is 60 months and subject participation duration is 6 months. Given the safety of prolonged therapy with nitazoxanide, lack of interactions with common post-transplant medications, putative antiviral activity and prolonged duration of viral shedding we are assessing 56 doses of therapy. The longitudinal monitoring phase will provide useful information on the course of host and viral responses in subjects with chronic Norovirus infection with and without treatment. Randomization will be stratified by age group (pediatric (12 through 17 years) vs. adult (greater than or equal to 18 years)), chronicity of Norovirus-associated symptoms (acute (less than 14 days) vs. chronic (greater than or equal to 14 days)) and transplant type (solid organ (SOT)) vs. hematopoietic stem cell transplant (HSCT)). Enrolled subjects will participate in 2 phases of the study: Treatment Phase, which will include dosing with the assigned study agent for 28 days. Longitudinal Monitoring Phase which will include telephone call on Days 35, 53, 113, 173. Primary objective is 1) to assess the clinical efficacy of nitazoxanide for the management of acute and chronic Norovirus in transplant recipients.
This is a phase 2 multi-center, double-blind, placebo-controlled study of the efficacy and safety of nitazoxanide for the treatment of solid organ and hematopoietic stem cell transplant recipients with symptomatic diarrhea due to Norovirus. The study involves a total of 160 Hematopoietic Stem Cell or Solid Organ transplant recipients, equal to or greater than 12 years of age with diagnosis of Norovirus who will be selected and randomly assigned (1:1) into two treatment groups: nitazoxanide or placebo. The study duration is approximately 60 months and subject participation duration is approximately 6 months. Given the safety of prolonged therapy with nitazoxanide, lack of interactions with common post-transplant medications, putative antiviral activity and prolonged duration of viral shedding we are assessing 56 doses of therapy. The longitudinal monitoring phase will provide useful information on the course of host and viral responses in subjects with chronic Norovirus infection with and without treatment. Randomization will be stratified by age group (pediatric (12 through 17 years) vs. adult (greater than or equal to 18 years)), chronicity of Norovirus-associated symptoms (acute (less than 14 days) vs. chronic (greater than or equal to 14 days)) and transplant type (solid organ (SOT)) vs. hematopoietic stem cell transplant (HSCT)). Enrolled subjects will participate in 2 phases of the study: Treatment Phase, which will include dosing with the assigned study agent for 28 days. Longitudinal Monitoring Phase which will include telephone call on Days 35, 53, 113, 173. Primary objective is 1) to assess the clinical efficacy of nitazoxanide for the management of acute and chronic Norovirus in transplant recipients. Secondary Objectives are 1) to assess the virologic efficacy of nitazoxanide and 2) to assess the safety of nitazoxanide for the management of acute and chronic Norovirus in transplant recipients.
237 studies on the registry are indexed under Gastroenteritis; 16 are open to participants now.
This study's enrollment of 31 is below the median of 136 across 164 interventional studies indexed under Gastroenteritis.
Browse Gastroenteritis studies →National Institute of Allergy and Infectious Diseases (NIAID) is the lead sponsor of 2,446 studies on the registry; 179 are open to participants now.
Of its 405 completed or terminated interventional studies of FDA-regulated products, 302 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Subjects should meet all of the following inclusion criteria:
Subjects must be of non- or if of childbearing potential, must be using an effective method of or must be abstinent.
Exclusion Criteria:
Subjects meeting any of the exclusion criteria at baseline will be excluded from study participation:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
500 mg (one tablet) nitazoxanide by mouth twice daily with food for 56 consecutive doses. N=80
Drug: Nitazoxanide
Placebo (one tablet) by mouth twice daily with food for 56 consecutive doses. N=80
Other: Placebo
One 500 mg tablet twice daily with food for 56 consecutive doses
One tablet twice daily with food for 56 consecutive doses
Time to Initial Clinical Resolution of Norovirus Symptoms
Time (in days) from randomization until the study day when clinical resolution occurred. Clinical resolution was assessed from participant's daily diaries and was defined as cessation of vomiting and no stools classified by the Bristol Stool Chart as diarrhea (Type 6 or 7) for at least 48 hours.
Time frame: 48 hours through Day 180
Number of Participants Experiencing Laboratory Adverse Events (AEs)
Participants experiencing at least one new laboratory adverse event. Laboratory parameters include White Blood Cell (WBC), Hemoglobin, Platelet Count, Creatinine, Alkaline Phosphatase, Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Blood Urea Nitrogen (BUN), and Bilirubin. Laboratory results were considered AEs using the following thresholds : WBC greater than the upper limit of normal (ULN), hemoglobin less than the lower limit of normal (LLN), platelet count less than the LLN; creatinine greater than the ULN; alkaline phosphatase greater than the ULN; ALT greater than the ULN, AST greater than the ULN, BUN greater than or equal to the ULN, and bilirubin greater than the ULN. ULN and LLN values differed by site, sex, and age category.
Time frame: Day 1 (baseline) through Day 60
Change in Viral Titer (Day 1 to Day 180)
Change in viral titer defined as the difference between the Day 180 viral titer and the Day 1 viral titer. Participants were analyzed for the viral load test type (Norovirus GII or Norovirus GI) that they tested positive for at baseline (Day 1).
Time frame: Day 1 (baseline) and Day 180
Number of Participants Reporting Hospitalization
Hospitalizations included any admission to a hospital for treatment and were not reported as Serious Adverse Events (SAEs).
Time frame: Day 1 (baseline) through Day 60
Number of Participants Reporting Protocol-Specified SAEs
Protocol-specified SAEs included any adverse event or suspected adverse reaction which, in the view of the investigator or sponsor, resulted in any of the following: death, life threatening adverse event, persistent or significant disability or incapacity or substantial disruption of the ability to conduct normal life function, congenital anomaly or birth defect, or an important medical event that may jeopardize the participant and require medical or surgical intervention. Hospitalizations were collected as a secondary outcome measure and were not reported as SAEs.
Time frame: Day 1 (baseline) through Day 60
Number of Participants Experiencing Unsolicited Non-Serious Adverse Events
Unsolicited adverse events were defined as any non-serious clinical adverse events that were not collected as clinical outcome measures and resulted in either modification in the administration of study drug or discontinuation of the study drug.
Time frame: Day 1 (baseline) through Day 60
Time to First Negative Viral Load
Time (in days) from randomization until the first study day the participant had either a negative result or a result less than the lower limit of quantitation (LLOQ) for the viral load test type (Norovirus GII or Norovirus GI) that they initially tested positive for at baseline. Participants were analyzed for the viral load test type (Norovirus GII or Norovirus GI) that they tested positive for at baseline (Day 1).
Time frame: Day 1 (baseline) and Day 180
| Milestone | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Started | 16 | 15 |
| Completed | 12 | 10 |
| Not completed | 4 | 5 |
| Withdrew: Death | 0 | 2 |
| Withdrew: Lost to follow-up | 0 | 1 |
| Withdrew: Protocol violation | 0 | 1 |
| Withdrew: Withdrawal by subject | 3 | 1 |
| Withdrew: Covid-19 pandemic | 1 | 0 |
Time (in days) from randomization until the study day when clinical resolution occurred. Clinical resolution was assessed from participant's daily diaries and was defined as cessation of vomiting and no stools classified by the Bristol Stool Chart as diarrhea (Type 6 or 7) for at least 48 hours.
| days | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Time to Initial Clinical Resolution of Norovirus Symptoms | 19 (1 to 31) | 11 (2 to 14) |
Participants experiencing at least one new laboratory adverse event. Laboratory parameters include White Blood Cell (WBC), Hemoglobin, Platelet Count, Creatinine, Alkaline Phosphatase, Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Blood Urea Nitrogen (BUN), and Bilirubin. Laboratory results were considered AEs using the following thresholds : WBC greater than the upper limit of normal (ULN), hemoglobin less than the lower limit of normal (LLN), platelet count less than the LLN; creatinine greater than the ULN; alkaline phosphatase greater than the ULN; ALT greater than the ULN, AST greater than the ULN, BUN greater than or equal to the ULN, and bilirubin greater than the ULN. ULN and LLN values differed by site, sex, and age category.
| Participants | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Number of Participants Experiencing Laboratory Adverse Events (AEs) | 11 | 13 |
Change in viral titer defined as the difference between the Day 180 viral titer and the Day 1 viral titer. Participants were analyzed for the viral load test type (Norovirus GII or Norovirus GI) that they tested positive for at baseline (Day 1).
| titer | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Norovirus GII | -3.9 ± 9.8 | -4.2 ± 6.8 |
| Norovirus GI | -11.4 ± 3.5 | — |
Hospitalizations included any admission to a hospital for treatment and were not reported as Serious Adverse Events (SAEs).
| Participants | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Number of Participants Reporting Hospitalization | 4 | 7 |
Protocol-specified SAEs included any adverse event or suspected adverse reaction which, in the view of the investigator or sponsor, resulted in any of the following: death, life threatening adverse event, persistent or significant disability or incapacity or substantial disruption of the ability to conduct normal life function, congenital anomaly or birth defect, or an important medical event that may jeopardize the participant and require medical or surgical intervention. Hospitalizations were collected as a secondary outcome measure and were not reported as SAEs.
| Participants | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Number of Participants Reporting Protocol-Specified SAEs | 0 | 2 |
Unsolicited adverse events were defined as any non-serious clinical adverse events that were not collected as clinical outcome measures and resulted in either modification in the administration of study drug or discontinuation of the study drug.
| Participants | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Number of Participants Experiencing Unsolicited Non-Serious Adverse Events | 2 | 0 |
Time (in days) from randomization until the first study day the participant had either a negative result or a result less than the lower limit of quantitation (LLOQ) for the viral load test type (Norovirus GII or Norovirus GI) that they initially tested positive for at baseline. Participants were analyzed for the viral load test type (Norovirus GII or Norovirus GI) that they tested positive for at baseline (Day 1).
| days | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Norovirus GII | NA (45 to NA) | NA (120 to NA) |
| Norovirus GI | NA (12 to NA) | 22 (13 to NA) |
Collected over 180 days. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Nitazoxanide (500 mg) | 0/16 (0%) | 0/16 (0%) | 12/16 (75%) |
| Placebo | 2/15 (13.3%) | 2/15 (13.3%) | 13/15 (86.7%) |
| Event | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Hypoxic Respiratory FailureRespiratory, thoracic and mediastinal disorders | 0/16 | 1/15 |
| UremiaRenal and urinary disorders | 0/16 | 1/15 |
| Event | Nitazoxanide (500 mg) | Placebo |
|---|---|---|
| Blood Urea IncreasedInvestigations | 7/16 | 3/15 |
| Blood Creatinine IncreasedInvestigations | 6/16 | 3/15 |
| Haemoglobin DecreasedInvestigations | 3/16 | 5/15 |
| Aspartate Aminotransferase IncreasedInvestigations | 2/16 | 3/15 |
| Blood Alkaline Phosphatase IncreasedInvestigations | 2/16 | 3/15 |
| White Blood Cell Count DecreasedInvestigations | 1/16 | 3/15 |
| Platelet Count DecreasedInvestigations | 3/16 | 0/15 |
| Blood Bilirubin IncreasedInvestigations | 1/16 | 2/15 |
| White Blood Cell Count IncreasedInvestigations | 0/16 | 2/15 |
| Alanine Aminotransferase IncreasedInvestigations | 2/16 | 1/15 |
| Age, Continuous(years) | Nitazoxanide (500 mg) | Placebo | Total |
|---|---|---|---|
| Mean | 58.9 ± 10.7 | 55.8 ± 14.0 | 57.4 ± 12.3 |
| Sex: Female, Male(Participants) | Nitazoxanide (500 mg) | Placebo | Total |
|---|---|---|---|
| Female | 7 | 8 | 15 |
| Male | 9 | 7 | 16 |
| Ethnicity (NIH/OMB)(Participants) | Nitazoxanide (500 mg) | Placebo | Total |
|---|---|---|---|
| Hispanic or Latino | 2 | 1 | 3 |
| Not Hispanic or Latino | 13 | 12 | 25 |
| Unknown or Not Reported | 1 | 2 | 3 |
| Race (NIH/OMB)(Participants) | Nitazoxanide (500 mg) | Placebo | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 0 | 0 | 0 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 |
| Black or African American | 4 | 2 | 6 |
| White | 11 | 13 | 24 |
| More than one race | 0 | 0 | 0 |
| Unknown or Not Reported | 1 | 0 | 1 |
| Duration of symptoms(Participants) | Nitazoxanide (500 mg) | Placebo | Total |
|---|---|---|---|
| Acute | 4 | 3 | 7 |
| Chronic | 12 | 12 | 24 |
| Transplant type(Participants) | Nitazoxanide (500 mg) | Placebo | Total |
|---|---|---|---|
| Solid organ | 15 | 15 | 30 |
| Hematopoietic Stem Cell Transplant | 1 | 0 | 1 |
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Studies of the drug tested here: Nitazoxanide
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