ALINIA Tablet / Oral suspension Ref.[50382] Active ingredients: Nitazoxanide

Absorption

Single Dosing

Following oral administration of ALINIA Tablets or Oral Suspension, the parent drug, nitazoxanide, is not detected in plasma. The pharmacokinetic parameners of the metabolites, tizoxanide and tizoxanide glucuronide are shown in Tables 2 and 3 below.

Table 2. Mean (+/- SD) plasma pharmacokinetic parameters of tizoxanide and tizoxanide glucuronide following administration of a single dose of one 500 mg ALINIA Tablet with food to subjects ≥12 years of age

*T_max is given as a Mean (Range)

Table 3. Mean (+/-SD) plasma pharmacokinetic of tizoxanide and tizoxanide glucuronide parameter values following administration of single dose of ALINIA for Oral Suspension with food to subjects ≥1year of age

^* T_max is given as a Mean (Range)

Multiple dosing

Following oral administration of a single ALINIA Tablet every 12 hours for 7 consecutive days, there was no significant accumulation of nitazoxanide metabolites tizoxanide or tizoxanide glucuronide detected in plasma.

Bioavailability

ALINIA for Oral Suspension is not bioequivalent to ALINIA Tablets. The relative bioavailability of the suspension compared to the tablet was 70%.

When ALINIA Tablets are administered with food, the AUC_t of tizoxanide and tizoxanide glucuronide in plasma is increased almost two-fold and the C_max is increased by almost 50%.

When ALINIA for Oral Suspension was administered with food, the AUC_t of tizoxanide and tizoxanide glucuronide increased by about 45-50% and the C_max increased by ≤10%.

ALINIA Tablets and ALINIA for Oral Suspension were administered with food in clinical trials and hence they are recomended to be administered with food [see Dosage and Administration (2.1)].

Distribution

In plasma, more than 99% of tizoxanide is bound to proteins.

Elimination

Metabolism

Following oral administration in humans, nitazoxanide is rapidly hydrolyzed to an active metabolite, tizoxanide (desacetyl-nitazoxanide). Tizoxanide then undergoes conjugation, primarily by glucuronidation.

Excretion

Tizoxanide is excreted in the urine, bile and feces, and tizoxanide glucuronide is excreted in urine and bile. Approximately two-thirds of the oral dose of nitazoxanide is excreted in the feces and one-third in the urine.

Specific Populations

Pediatric Patients

The pharmacokinetics of tizoxanide and tizoxanide glucuronide following administration of ALINIA Tablets in pediatric patients 12-17 years of age are provided above in Table 2. The pharmacokinetics of tizoxanide and tizoxanide glucuronide following administration of ALINIA for Oral Suspension in pediatric patients 1-11 years of age are provided above in Table 3.

Drug Interaction Studies

In vitro studies have demonstrated that tizoxanide has no significant inhibitory effect on cytochrome P450 enzymes.

Mechanism of Action

The antiprotozoal activity of nitazoxanide is believed to be due to interference with the pyruvate:ferredoxin oxidoreductase (PFOR) enzyme-dependent electron transfer reaction which is essential to anaerobic energy metabolism. Studies have shown that the PFOR enzyme from G. lamblia directly reduces nitazoxanide by transfer of electrons in the absence of ferredoxin. The DNA-derived PFOR protein sequence of C. parvum appears to be similar to that of G. lamblia. Interference with the PFOR enzyme-dependent electron transfer reaction may not be the only pathway by which nitazoxanide exhibits antiprotozoal activity.

Resistance

A potential for development of resistance by C. parvum or G. lamblia to nitazoxanide has not been examined.

Antimicrobial Activity

Nitazoxanide and its metabolite, tizoxanide, are active in vitro in inhibiting the growth of (i) sporozoites and oocysts of C. parvum and (ii) trophozoites of G. lamblia.

Susceptibility Test Methods

For protozoa such as C. parvum and G. lamblia, standardized tests for use in clinical microbiology laboratories are not available.

Carcinogenesis

Long-term carcinogenicity studies have not been conducted.

Mutagenesis

Nitazoxanide was not genotoxic in the Chinese hamster ovary (CHO) cell chromosomal aberration assay or the mouse micronucleus assay. Nitazoxanide was genotoxic in one tester strain (TA100) in the Ames bacterial mutation assay.

Impairment of Fertility

Nitazoxanide did not adversely affect male or female fertility in the rat at 2400 mg/kg/day (approximately 20 times the clinical adult dose adjusted for body surface area).

14.1 Diarrhea Caused by G. lamblia

Diarrhea caused by G. lamblia in adults and adolescents 12 years of age or older

In a double-blind, controlled trial (Study 1) conducted in Peru and Egypt in adults and adolescents with diarrhea and with one or more enteric symptoms (e.g., abdominal pain, nausea, vomiting, fever, abdominal distention, loss of appetite, flatulence) caused by G. lamblia, a three-day course of treatment with ALINIA Tablets administered 500 mg twice daily was compared with a placebo tablet for 3 days. A third group of patients received open-label ALINIA for Oral Suspension administered 500 mg/25 mL of suspension twice daily for 3 days. A second double-blind, controlled trial (Study 2) conducted in Egypt in adults and adolescents with diarrhea and with or without enteric symptoms (e.g., abdominal colic, abdominal tenderness, abdominal cramps, abdominal distention, fever, bloody stool) caused by G. lamblia compared ALINIA Tablets administered 500 mg twice daily for 3 days to a placebo tablet. For both of these studies, clinical response was evaluated 4 to 7 days following the end of treatment. A clinical response of ‘well’ was defined as ‘no symptoms, no watery stools and no more than 2 soft stools with no hematochezia within the past 24 hours’ or ‘no symptoms and no unformed stools within the past 48 hours.’ The following clinical response rates were obtained:

Table 4. Adult and Adolescent Patients with Diarrhea Caused by G. lamblia:

Clinical Response Rates* 4 to 7 Days Post-therapy

% (Number of Successes/Total)

^* Includes all patients randomized with G. lamblia as the sole pathogen. Patients failing to complete the studies were treated as failures.
^¶ Clinical response rates statistically significantly higher when compared to placebo.
^§ The 95% confidence interval of the difference in response rates for the tablet and suspension is (-14%, 17%).

Some patients with ‘well’ clinical responses had G. lamblia cysts in their stool samples 4 to 7 days following the end of treatment. The relevance of stool examination results in these patients is unknown. Patients should be managed based upon clinical response to treatment.

Diarrhea caused by G. lamblia in pediatric patients 1 through 11 years of age

In a randomized, controlled trial conducted in Peru in 110 pediatric patients with diarrhea and with or without enteric symptoms (e.g., abdominal distention, right iliac fossa tenderness) caused by G. lamblia, a three-day course of treatment with nitazoxanide (100 mg twice daily in pediatric patients ages 24-47 months, 200 mg twice daily in pediatric patients ages 4 through 11 years) was compared to a five-day course of treatment with metronidazole (125 mg twice daily in pediatric patients ages 2 through 5 years, 250 mg twice daily in pediatric patients ages 6 through 11 years). Clinical response was evaluated 7 to 10 days following initiation of treatment with a ‘well’ response defined as ‘no symptoms, no watery stools and no more than 2 soft stools with no hematochezia within the past 24 hours’ or ‘no symptoms and no unformed stools within the past 48 hours.’ The following clinical cure rates were obtained:

Table 5. Clinical Response Rates in Pediatric Patients 7 to 10 Days Following Initiation of Therapy:

Intent-to-Treat and Per Protocol Analyses

% (Number of Successes/Total), [95% Confidence Interval]

^† Intent-to-treat analysis includes all patients randomized with patients not completing the study treated as failures.
^¶ Per protocol analysis includes only patients who took all of their medication and completed the study. Seven patients in each treatment group missed at least one dose of medication and one in the metronidazole treatment group was lost to follow-up.
^§ 95% Confidence Interval on the difference in response rates (nitazoxanide-metronidazole).

Some patients with ‘well’ clinical responses had G. lamblia cysts in their stool samples 4 to 7 days following the end of treatment. The relevance of stool examination results in these patients is unknown. Patients should be managed based upon clinical response to treatment.

14.2 Diarrhea Caused by C. parvum

Diarrhea caused by C. parvum in adults and adolescents 12 years of age or older

In a double-blind, controlled trial conducted in Egypt in adults and adolescents with diarrhea and with or without enteric symptoms (e.g., abdominal pain/cramps, nausea, vomiting) caused by C. parvum, a three-day course of treatment with ALINIA Tablets administered 500 mg twice daily was compared with a placebo tablet for 3 days. A third group of patients received open-label ALINIA for Oral Suspension administered 500 mg/25 mL of suspension twice daily for 3 days. Clinical response was evaluated 4 to 7 days following the end of treatment. A clinical response of ‘well’ was defined as ‘no symptoms, no watery stools and no more than 2 soft stools within the past 24 hours’ or ‘no symptoms and no unformed stools within the past 48 hours.’ The following clinical response rates were obtained:

Table 6. Clinical Response Rates in Adult and Adolescent Patients 4 to 7 Days Post-therapy:

% (Number of Successes/Total)

^* Includes all patients randomized with C. parvum as the sole pathogen. Patients failing to complete the study were treated as failures.
^¶ Clinical response rates statistically significantly higher when compared to placebo.
^§ The 95% confidence interval of the difference in response rates for the tablet and suspension is (-10%, 28%).

In a second double-blind, placebo-controlled study of nitazoxanide tablets conducted in Egypt in adults and adolescents with diarrhea and with or without enteric symptoms (e.g., abdominal colic, abdominal cramps, epigastric pain) caused by C. parvum as the sole pathogen, clinical and parasitological response rates showed a similar trend to the first study. Clinical response rates, evaluated 2 to 6 days following the end of treatment, were 71% (15/21) in the nitazoxanide group and 42.9% (9/21) in the placebo group.

Some patients with ‘well’ clinical responses had C. parvum oocysts in their stool samples 4 to 7 days following the end of treatment. The relevance of stool examination results in these patients is unknown. Patients should be managed based upon clinical response to treatment.

Diarrhea caused by C. parvum in pediatric patients 1 through 11 years of age

In two double-blind, controlled trials in pediatric patients with diarrhea and with or without enteric symptoms (e.g., abdominal distention, colic, left iliac fossa tenderness) caused by C. parvum, a three-day course of treatment with nitazoxanide (100 mg twice daily in pediatric patients ages 12-47 months, 200 mg twice daily in pediatric patients ages 4 through 11 years) was compared with a placebo. One study was conducted in Egypt in outpatients ages 1 through 11 years with diarrhea caused by C. parvum. Another study was conducted in Zambia in malnourished pediatric patients admitted to the hospital with diarrhea caused by C. parvum. Clinical response was evaluated 3 to 7 days post-therapy with a ‘well’ response defined as ‘no symptoms, no watery stools and no more than 2 soft stools within the past 24 hours’ or ‘no symptoms and no unformed stools within the past 48 hours.’ The following clinical response rates were obtained:

Table 7. Clinical Response Rates in Pediatric Patients 3 to 7 Days Post-therapy Intent-to-Treat Analyses:

% (Number of Successes/Total)

^* Clinical response rates statistically significantly higher compared to placebo.
^¶ 60% considered severely underweight, 19% moderately underweight, 17% mild underweight.

Some patients with ‘well’ clinical responses had C. parvum oocysts in their stool samples 3 to 7 days following the end of treatment. The relevance of stool examination results in these patients is unknown. Patients should be managed based upon clinical response to treatment.

Diarrhea caused by C. parvum in Acquired Immune Deficiency Syndrome (AIDS) patients

A double-blind, placebo-controlled trial did not produce clinical cure rates that were significantly different from the placebo control when conducted in hospitalized, severely malnourished pediatric patients with acquired immune deficiency syndrome (AIDS) in Zambia. In this study, the pediatric patients received a three day course of nitazoxanide suspension (100 mg twice daily in pediatric patients ages 12-47 months, 200 mg twice daily in pediatric patients ages 4 through 11 years) and were evaluated for response four days after the end of treatment.