What is Nitazoxanide Used For?
Nitazoxanide is an FDA-approved antiparasitic medication primarily used to treat diarrhea caused by Cryptosporidium parvum and Giardia lamblia in immunocompetent patients, with additional off-label uses for other protozoal infections. 1, 2
FDA-Approved Indications
Cryptosporidiosis
- Nitazoxanide is approved for treating diarrhea caused by Cryptosporidium parvum in both children (ages 1-11 years) and adults. 2
- Pediatric dosing: 100 mg orally twice daily for ages 1-3 years; 200 mg orally twice daily for ages 4-11 years. 3, 1
- Adult dosing: 500-1000 mg orally twice daily. 1
- Clinical response rates in immunocompetent children reach 88% versus 38% with placebo. 3, 1, 2
- In adults, clinical response rates are 96% with tablets and 87% with suspension versus 41% with placebo. 2
Giardiasis
- Nitazoxanide is approved as an alternative treatment for Giardia lamblia infection. 1, 4
- The Infectious Diseases Society of America lists tinidazole as first-line, with nitazoxanide as an approved alternative. 1
- Dosing for children ages 4-11 years: 200 mg twice daily for 3 days. 4, 2
- Clinical cure rates of 85% in intent-to-treat analysis versus 80% with metronidazole. 2
Off-Label/Investigational Uses
Other Protozoal Infections
- Cyclospora cayetanensis: Alternative when TMP-SMX cannot be used, though data is limited. 1
- Cystoisospora belli: Potential second-line alternative when TMP-SMX or pyrimethamine are unsuitable. 1
- Enterocytozoon bieneusi (Microsporidiosis): Recommended by CDC for HIV-infected adults. 3, 1
Viral Gastroenteritis
- Rotavirus enteritis: Dosing at 7.5 mg/kg twice daily orally, though only assessed in immunocompetent pediatric patients. 3
Critical Clinical Considerations
Immunocompromised Patients
- Nitazoxanide has significantly reduced efficacy in HIV-infected patients, particularly those with CD4 counts <50 cells/µL. 3, 1
- In HIV-infected children, nitazoxanide was no more effective than placebo in a Zambian study. 3
- Should only be used in HIV-infected patients with cryptosporidiosis when combined with effective antiretroviral therapy (cART) and CD4 >50 cells/µL. 1
- Consider longer treatment duration (14 days instead of 3 days) in immunocompromised adults, though evidence is limited. 5
- Combination therapy with nitazoxanide plus azithromycin shows promise in allogeneic stem cell transplant patients, but reliable recommendations cannot be made based on current data. 3, 5
Essential Supportive Care
- Aggressive supportive care is mandatory and often determines outcomes, particularly in young children who can rapidly decompensate. 3, 5
- Provide hydration and correction of electrolyte abnormalities. 3, 1
- Nutritional supplementation should be provided. 3, 1
- Use antimotility agents with caution in young children. 3
Important Caveats
- Some patients with "well" clinical responses still have parasites in stool samples 3-7 days post-treatment; patients should be managed based on clinical response, not stool examination results. 2
- The drug is well tolerated with primarily mild gastrointestinal side effects and no significant documented drug-drug interactions. 6, 7
- For HIV-infected patients with cryptosporidiosis, immune reconstitution through HAART is the most important intervention. 3, 5