Nitazoxanide syrup
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Nitazoxanide is a broad-spectrum antiparasitic and antiviral drug. The syrup form is used primarily in children. Let me pull up detailed information from the medical library.
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Here is a complete reference on Nitazoxanide Syrup (Oral Suspension):
Nitazoxanide Syrup (Oral Suspension)
Brand name: Alinia
Formulation: 100 mg / 5 mL oral suspension (powder for reconstitution - add 48 mL water to make final suspension)
Drug class: 5-nitrothiazole antiprotozoal / broad-spectrum antiparasitic
Drug Description
Nitazoxanide is a synthetic, oral nitrothiazolyl-salicylamide prodrug with broad-spectrum activity against intestinal protozoa and helminths. The syrup formulation is specifically intended for children aged 1-11 years, as the 500 mg tablet contains more drug than the pediatric dose requires.
- Katzung's Basic and Clinical Pharmacology, 16th Ed, p. 1454
- Goodman & Gilman's The Pharmacological Basis of Therapeutics
Mechanism of Action
Nitazoxanide interferes with the pyruvate:ferredoxin oxidoreductase (PFOR) enzyme-dependent electron transfer reaction, which is essential to anaerobic energy metabolism in protozoan and bacterial species. The PFOR enzyme of Giardia lamblia directly reduces nitazoxanide by electron transfer. A similar PFOR sequence is found in Cryptosporidium parvum. This mechanism may not be the only pathway involved.
Unlike metronidazole, nitazoxanide and its metabolites are free of mutagenic effects.
- Harrison's Principles of Internal Medicine 22E (2025)
- Goodman & Gilman's
Pharmacokinetics (ADME)
| Parameter | Detail |
|---|---|
| Absorption | Rapid after oral administration; improved with food |
| Prodrug conversion | Rapidly hydrolyzed to active metabolite tioxanide (desacetyl-nitazoxanide) |
| Further metabolism | Tioxanide undergoes glucuronidation → tioxanide glucuronide |
| Protein binding | >99.9% (plasma protein bound) |
| Tmax | 1-4 hours after dosing |
| Excretion | Tioxanide: urine, bile, feces; Tioxanide glucuronide: urine and bile |
| Renal/hepatic impairment | Not formally studied; use with caution |
Drug interaction caution: Due to >99.9% plasma protein binding, nitazoxanide may compete with other highly protein-bound drugs that have a narrow therapeutic index.
Indications (Approved)
- Giardiasis (Giardia lamblia / G. intestinalis) - efficacy 85-90%
- Cryptosporidiosis (Cryptosporidium parvum) - efficacy 56-88% in immunocompetent patients
Limitation: NOT effective for diarrhea caused by C. parvum in HIV-infected or immunodeficient patients (FDA label). Immunocompromised patients may require extended therapy (2 weeks or longer).
Off-Label / Extended Spectrum Uses
Nitazoxanide has shown efficacy against a wide range of organisms:
- Entamoeba histolytica (amebiasis)
- Blastocystis hominis
- Cyclospora cayetanensis
- Isospora belli
- Trichomonas vaginalis
- Hymenolepis nana, Trichuris trichiura, Ascaris lumbricoides, Enterobius vermicularis (helminths)
- Fasciola hepatica
- Helicobacter pylori (as part of quadruple therapy)
- Metronidazole-resistant protozoal strains
Dosage - Syrup (100 mg/5 mL)
| Age Group | Dose | Frequency | Duration |
|---|---|---|---|
| 1-3 years | 5 mL (100 mg) | Every 12 hours | 3 days |
| 4-11 years | 10 mL (200 mg) | Every 12 hours | 3 days |
| <1 year | Not established | - | - |
| ≥12 years | Switch to 500 mg tablet | Every 12 hours | 3 days |
Always administer with food.
For immunocompromised patients with cryptosporidiosis: extend therapy to 2 weeks or longer (and optimize antiretroviral therapy if HIV-positive).
Suspension Preparation
- Tap bottle until all powder flows freely
- Add approximately half of 48 mL water first and shake vigorously
- Add remaining water and shake again
- Final volume makes a 100 mg/5 mL suspension
- Keep refrigerated; shake well before each use
Adverse Effects
Nitazoxanide is generally well tolerated. Adverse effects are uncommon and usually mild:
- Abdominal pain
- Diarrhea
- Nausea / vomiting
- Headache
- Greenish tint to urine (benign, due to drug metabolites)
Note: these adverse event rates are comparable to placebo in trials.
Contraindications
- Hypersensitivity to nitazoxanide or any component of the formulation
- Tablets (500 mg) must not be used in children ≤11 years (dose mismatch; use oral suspension instead)
Safety in Special Populations
| Population | Notes |
|---|---|
| Pregnancy | Former FDA Category B; no teratogenicity in animal studies; no human data |
| Lactation | Caution advised; data limited |
| HIV/Immunocompromised | Reduced efficacy for cryptosporidiosis; extended courses needed |
| Hepatic impairment | Not studied; use with caution |
| Renal impairment | Not studied; use with caution |
Key Distinguishing Features
- Broad spectrum - single agent can treat mixed intestinal infections (protozoa + helminths)
- Active against metronidazole-resistant Giardia
- Not mutagenic (unlike metronidazole/tinidazole)
- Short 3-day treatment course
- Pediatric-friendly syrup formulation (age 1-11)
Sources: Goodman & Gilman's Pharmacological Basis of Therapeutics; Harrison's Principles of Internal Medicine 22E (2025); Katzung's Basic and Clinical Pharmacology 16th Ed; FDA Prescribing Information (Alinia)
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