Nitazoxanide is a broad-spectrum antiparasitic drug that inhibits the pyruvate-ferredoxin oxidoreductase pathway in protozoans and bacteria, preventing anaerobic metabolism. It is better tolerated than metronidazole and its metabolites lack mutagenic effects. After oral administration, nitazoxanide is rapidly hydrolyzed to its active metabolite tizoxanide, which undergoes conjugation and is excreted in urine, bile, and feces. Common minor adverse effects include nausea, vomiting, diarrhea, and abdominal pain. Nitazoxanide shows activity against various parasites and is used to treat Giardia intestinalis infection and diarrhea caused by

1. NITAZOXANIDE:
A. CLASS: Broad-spectrum antiparasitic/antiprotozoal (N-nitrothiazolyl salicylamide).
B. MECHANISM OF ACTION: (Ref.: Goodman & Gilman, 13th ed., Pg.: 993; Katzung, 14th
ed., Pg.: 933-934; Antibiotics: A guide to commonly used antimicrobials, 2nd ed., Pg.: 5)
- Drug  inhibits pyruvate-ferredoxin oxidoreductase (PFOR) pathway  prevents
anaerobic metabolism in protozoan & bacterial species (Raether & Hanel, 2003)
- Drug  differs from metronidazole, in that:
a. Acts against metronidazole-resistant protozoal strains
b. Well-tolerated
c. Nitazoxanide & its metabolites are free from mutagenic effects (contrary to that
of metronidazole).
C. PHARMACOKINETIC PROFILE: (Ref.: Goodman & Gilman, 13th ed., Pg.: 993-994;
Katzung, 14th ed., Pg.: 933; Antibiotics: A guide to commonly used antimicrobials, 2nd ed.,
Pg.: 5)
- After oral administration  drug is hydrolyzed rapidly to its active metabolite
(tizoxanide)
- Tizoxanide  undergoes conjugation to tizoxanide glucuronide
- Excellent bioavailability (with oral dose)
- Maximum plasma drug concentration (C) is achieved 1-4 hours after oral
administration
- PPB: 99.9%
- Tizoxanide  excreted in urine, bile & feces (Raether & Hanel, 2003)
- Tizoxanide glucuronide  excreted in urine & bile (Raether & Hanel, 2003).

2. D. ADVERSEEFFECTS: (Ref.: Goodman & Gilman, 13th ed., Pg.: 993; Antibiotics: A guide to
commonly used antimicrobials, 2nd ed., Pg.: 5)
- Minor ADRs observed, that include:
a. Nausea & vomiting
b. Diarrhea
c. Abdominal pain
- Greenish discoloration of urine.
E. DRUG INTERACTIONS: (Ref.: Antibiotics: A guide to commonly used antimicrobials,
2nd ed., Pg.: 5)
1. Nitazoxanide + Food  enhanced absorption of former!
F. ANTIMICROBIAL SPECTRUM: (Ref.: Goodman & Gilman, 13th ed., Pg.: 993;
Antibiotics: A guide to commonly used antimicrobials, 2nd ed., Pg.: 5)
- Nitazoxanide  shows activity against varying organisms, the chief ones being
Giardia lamblia & Cryptosporidium parvum
- Drug  inhibits growth of sporozoites & oocytes of C. parvum
- Drug  inhibits growth of trophozoites of G. intestinalis. E. histolytica & T. vaginalis
in vitro (Wright, 2012)
- Drug  also shows good activity against intestinal helminths (van den Enden, 2009).

3. G. DOSAGE ADJUSTMENTS IN SPECIAL POPULATIONS: (Ref.: Goodman & Gilman,
13th ed., Pg.: 994; Antibiotics: A guide to commonly used antimicrobials, 2nd ed., Pg.: 5)
1. IN RENAL IMPAIRMENT: Not necessary
2. IN HEPATIC IMPAIRMENT: Not necessary
3. IN PEDIATRICS (Drugs for Parasitic Infections, 2013; Flynn, 2012) :
For treatment of diarrhea due to G. lamblia & C. parvum:
- If age: 1-3 years  5 ml (100 mg nitazoxanide) , every 12 hours, for 3 days
- If age: 4-11 years  10 ml (200 mg nitazoxanide), every 12 hours, for 3 days
- If age ≥ 12 years  Either 1 tablet (500 mg nitazoxanide), every 12 hours, for 3 days,
OR 25 ml (500 mg nitazoxanide), every 12 hours, for 3 days.
4. PREGNANCY: Nitazoxanide is a pregnancy category “B” agent, according to animal
teratogenicity & fertility studies (Anderson & Curran, 2007).
H. CLINICAL USES: (Ref.: Goodman & Gilman, 13th ed., Pg.: 994; Antibiotics: A guide to
commonly used antimicrobials, 2nd ed., Pg.: 5)
- Nitazoxanide shows activity against the following organisms:
1. G. lamblia
2. C. parvum
3. E. histolytica
4. T. vaginalis
5. G. intestinalis
6. I. belli
7. C. cayetanensis
8. B. hominis
9. B. coli
10. E. bineusi
11. Ascaris lumbricoides
12. H. nana
13. F. hepatica
14. T. trichura
15. T. saginata.

4. - Major indications include:
1. G. intestinalis infection (Hill & Nash, 2014)
2. Diarrhea caused by Cryptosporidia, in adults & children > 1 year of age (Flynn,
2012)
3. Infections with G. intestinalis, resistant to metronidazole & albendazole (Wright,
2012).
VISHNU.R. NAIR,
PHARM.D INTERN,
NATIONAL COLLEGE OF PHARMACY (AMRI HOSPITAL ACADEMIC TRAINEE).