Zaxine

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Zaxine uses


1 INDICATIONS AND USAGE

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Zaxine and other antibacterial drugs, Zaxine when used to treat infection should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Zaxine is a rifamycin antibacterial indicated for:

  • Treatment of travelers’ diarrhea caused by noninvasive strains of Escherichia coli in adult and pediatric patients 12 years of age and older (1.1)
  • Reduction in risk of overt hepatic encephalopathy (HE) recurrence in adults (1.2)
  • Treatment of irritable bowel syndrome with diarrhea (IBS-D) in adults (1.3)

Limitations of Use

  • TD: Do not use in patients with diarrhea complicated by fever or blood in the stool or diarrhea due to pathogens other than Escherichia coli (1.1, 5.1)

1.1 Travelers’ Diarrhea

Zaxine is indicated for the treatment of travelers’ diarrhea (TD) caused by noninvasive strains of Escherichia coli in adults and pediatric patients 12 years of age and older.

Limitations of Use

Zaxine should not be used in patients with diarrhea complicated by fever or blood in the stool or diarrhea due to pathogens other than Escherichia coli.

1.2 Hepatic Encephalopathy

Zaxine is indicated for reduction in risk of overt hepatic encephalopathy recurrence in adults.

In the trials of Zaxine for HE, 91% of the patients were using lactulose concomitantly. Differences in the treatment effect of those patients not using lactulose concomitantly could not be assessed.

Zaxine has not been studied in patients with MELD (Model for End-Stage Liver Disease) scores >25, and only 8.6% of patients in the controlled trial had MELD scores over 19. There is increased systemic exposure in patients with more severe hepatic dysfunction .

1.3 Irritable Bowel Syndrome with Diarrhea

Zaxine is indicated for the treatment of irritable bowel syndrome with diarrhea (IBS-D) in adults.

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2 DOSAGE AND ADMINISTRATION


Condition


Recommended Dosage Regimen


TD


One 200 mg tablet 3 times a day for 3 days


HE (2.2)


One 550 mg tablet 2 times a day


IBS-D (2.3)


One 550 mg tablet 3 times a day for 14 days. Patients who experience recurrence can be retreated up to two times with the same regimen.

  • Zaxine can be taken with or without food. (2.4)

2.1 Dosage for Travelers’ Diarrhea

The recommended dose of Zaxine is one 200 mg tablet taken orally three times a day for 3 days.

2.2 Dosage for Hepatic Encephalopathy

The recommended dose of Zaxine is one 550 mg tablet taken orally two times a day.

2.3 Dosage for Irritable Bowel Syndrome with Diarrhea

The recommended dose of Zaxine is one 550 mg tablet taken orally three times a day for 14 days. Patients who experience a recurrence of symptoms can be retreated up to two times with the same dosage regimen.

2.4 Administration

Zaxine can be taken with or without food .

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3 DOSAGE FORMS AND STRENGTHS

Zaxine is a pink-colored biconvex tablet and is available in the following strengths:

  • 200 mg – a round tablet debossed with “Sx” on one side and plain on the other.
  • 550 mg – an oval tablet debossed with “rfx” on one side and plain on the other.

200 mg and 550 mg tablets (3)

4 CONTRAINDICATIONS

Zaxine is contraindicated in patients with a hypersensitivity to Zaxine, any of the rifamycin antimicrobial agents, or any of the components in Zaxine. Hypersensitivity reactions have included exfoliative dermatitis, angioneurotic edema, and anaphylaxis .

History of hypersensitivity to Zaxine, rifamycin antimicrobial agents, or any of the components of Zaxine (4)

5 WARNINGS AND PRECAUTIONS

  • Travelers’ Diarrhea Not Caused by E. coli: Zaxine was not effective in diarrhea complicated by fever and/or blood in the stool or diarrhea due to pathogens other than E. coli. If diarrhea symptoms get worse or persist for more than 24 to 48 hours, discontinue Zaxine and consider alternative antibiotics
  • Clostridium difficile-Associated Diarrhea: Evaluate if diarrhea occurs after therapy or does not improve or worsens during therapy (5.2)
  • Hepatic Impairment: Use with caution in patients with severe (Child-Pugh Class C) hepatic impairment (5.4, 8.7)
  • Concomitant P-glycoprotein inhibitor: Caution should be exercised when concomitant use of Zaxine and a P-glycoprotein inhibitor is needed (5.5, 7.2)

5.1 Travelers’ Diarrhea Not Caused by Escherichia coli

Zaxine was not found to be effective in patients with diarrhea complicated by fever and/or blood in the stool or diarrhea due to pathogens other than Escherichia coli.

Discontinue Zaxine if diarrhea symptoms get worse or persist more than 24 to 48 hours and alternative antibiotic therapy should be considered.

Zaxine is not effective in cases of travelers’ diarrhea due to Campylobacter jejuni. The effectiveness of Zaxine in travelers’ diarrhea caused by Shigella spp. and Salmonella spp. has not been proven. Zaxine should not be used in patients where Campylobacter jejuni, Shigella spp., or Salmonella spp. may be suspected as causative pathogens .

5.2 Clostridium difficile-Associated Diarrhea

Clostridium difficile-associated diarrhea has been reported with use of nearly all antibacterial agents, including Zaxine, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon which may lead to overgrowth of C. difficile.

C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.

If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

5.3 Development of Drug-Resistant Bacteria

Prescribing Zaxine for travelers’ diarrhea in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

5.4 Severe Hepatic Impairment

There is increased systemic exposure in patients with severe hepatic impairment. The clinical trials were limited to patients with MELD scores <25. Therefore, caution should be exercised when administering Zaxine to patients with severe hepatic impairment (Child-Pugh Class C) .

5.5 Concomitant use with P-glycoprotein Inhibitors

Concomitant administration of drugs that are P-glycoprotein inhibitors with Zaxine can substantially increase the systemic exposure to Zaxine. Caution should be exercised when concomitant use of Zaxine and a P-glycoprotein inhibitor such as cyclosporine is needed. In patients with hepatic impairment, a potential additive effect of reduced metabolism and concomitant P-glycoprotein inhibitors may further increase the systemic exposure to Zaxine .

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6 ADVERSE REACTIONS

Most common adverse reactions:

  • TD : Headache (6.1)
  • HE (≥10%): Peripheral edema, nausea, dizziness, fatigue, and ascites (6.1)
  • IBS-D (≥2%): ALT increased, nausea (6.1)

To report SUSPECTED ADVERSE REACTIONS, contact Salix Pharmaceuticals at 1-800-508-0024 and www. Salix.com or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Studies Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Travelers’ Diarrhea

The safety of Zaxine 200 mg taken three times a day was evaluated in patients with travelers’ diarrhea consisting of 320 patients in two placebo-controlled clinical trials with 95% of patients receiving three or four days of treatment with Zaxine. The population studied had a mean age of 31.3 (18-79) years of which approximately 3% were ≥65 years old, 53% were male and 84% were White, 11% were Hispanic.

Discontinuations due to adverse reactions occurred in 0.4% of patients. The adverse reactions leading to discontinuation were taste loss, dysentery, weight decrease, anorexia, nausea and nasal passage irritation.

The adverse reaction that occurred at a frequency ≥2% in XIFAXAN-treated patients (n=320) at a higher rate than placebo (n=228) in the two placebo-controlled trials of TD was:

  • headache (10% Zaxine, 9% placebo)

Hepatic Encephalopathy

The data described below reflect exposure to Zaxine in 348 patients, including 265 exposed for 6 months and 202 exposed for more than a year (mean exposure was 364 days). The safety of Zaxine 550 mg taken two times a day for reducing the risk of overt hepatic encephalopathy recurrence in adult patients was evaluated in a 6-month placebo-controlled clinical trial (n=140) and in a long term follow-up study (n=280). The population studied had a mean age of 56 (range: 21 to 82) years; approximately 20% of the patients were ≥65 years old, 61% were male, 86% were White, and 4% were Black. Ninety-one percent of patients in the trial were taking lactulose concomitantly. The most common adverse reactions that occurred at an incidence ≥5% and at a higher incidence in XIFAXAN-treated subjects than in the placebo group in the 6-month trial are provided in Table 1.


Number (%) of Patients


MedDRA Preferred Term


Zaxine Tablets

550 mg TWICE DAILY

n=140


Placebo

n=159


Peripheral edema


21 (15%)


13 (8%)


Nausea


20 (14%)


21 (13%)


Dizziness


18 (13%)


13 (8%)


Fatigue


17 (12%)


18 (11%)


Ascites


16 (11%)


15 (9%)


Muscle spasms


13 (9%)


11 (7%)


Pruritus


13 (9%)


10 (6%)


Abdominal pain


12 (9%)


13 (8%)


Anemia


11 (8%)


6 (4%)


Depression


10 (7%)


8 (5%)


Nasopharyngitis


10 (7%)


10 (6%)


Abdominal pain upper


9 (6%)


8 (5%)


Arthralgia


9 (6%)


4 (3%)


Dyspnea


9 (6%)


7 (4%)


Pyrexia


9 (6%)


5 (3%)


Rash


7 (5%)


6 (4%)


Irritable Bowel Syndrome with Diarrhea

The safety of Zaxine for the treatment of IBS-D was evaluated in 3 placebo-controlled studies in which 952 patients were randomized to Zaxine 550 mg three times a day for 14 days. Across the 3 studies, 96% of patients received at least 14 days of treatment with Zaxine. In Trials 1 and 2, 624 patients received only one 14-day treatment. Trial 3 evaluated the safety of Zaxine in 328 patients who received 1 open-label treatment and 2 double-blind repeat treatments of 14 days each over a period of up to 46 weeks. The combined population studied had a mean age of 47 (range: 18 to 88) years of whom approximately 11% of the patients were ≥65 years old, 72% were female, 88% were White, 9% were Black and 12% were Hispanic.

The adverse reaction that occurred at a frequency ≥2% in XIFAXAN-treated patients at a higher rate than placebo in Trials 1 and 2 for IBS-D was:

  • nausea (3% Zaxine, 2% placebo)

The adverse reactions that occurred at a frequency >2% in XIFAXAN-treated patients (n=328) at a higher rate than placebo (n=308) in Trial 3 for IBS-D during the double-blind treatment phase were:

  • ALT increased (XIFAXAN 2%, placebo 1%)
  • nausea (XIFAXAN 2%, placebo 1%)

Less Common Adverse Reactions

The following adverse reactions, presented by body system, were reported in less than 2% of patients in clinical trials of TD and IBS-D and in less than 5% of patients in clinical trials of HE:

Hepatobiliary disorders: Clostridium colitis

Investigations: Increased blood creatine phosphokinase

Musculoskeletal and connective tissue disorders: myalgia

6.2 Postmarketing Experience

The following adverse reactions have been identified during post-approval use of Zaxine. Because these reactions are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These reactions have been chosen for inclusion due to either their seriousness, frequency of reporting or causal connection to Zaxine.

Infections and Infestations

Cases of C. difficile-associated colitis have been reported .

General

Hypersensitivity reactions, including exfoliative dermatitis, rash, angioneurotic edema (swelling of face and tongue and difficulty swallowing), urticaria, flushing, pruritus and anaphylaxis have been reported. These events occurred as early as within 15 minutes of drug administration.

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7 DRUG INTERACTIONS

7.1 Effects of Zaxine on Other Drugs

Substrates of Cytochrome P450 enzymes

Zaxine is not expected to inhibit cytochrome P450 isoenzymes 1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and CYP3A4 in clinical use based on in vitro studies .

An in vitro study has suggested that Zaxine induces CYP3A4 . However, in patients with normal liver function, Zaxine at the recommended dosing regimen is not expected to induce CYP3A4. It is unknown whether Zaxine can have a significant effect on the pharmacokinetics of concomitant CYP3A4 substrates in patients with reduced liver function who have elevated Zaxine concentrations.

7.2 Effects of Other Drugs on Zaxine

In vitro studies suggested that Zaxine is a substrate of P-glycoprotein, OATP1A2, OATP1B1 and OATP1B3. Concomitant cyclosporine, an inhibitor of P-glycoprotein and OATPs, significantly increased the systemic exposure to Zaxine.

Cyclosporine

Co-administration of cyclosporine, with Zaxine resulted in 83-fold and 124-fold increases in Zaxine mean Cmax and AUC in healthy subjects. The clinical significance of this increase in systemic exposure is unknown .

8 USE IN SPECIFIC POPULATIONS

Pregnancy: May cause fetal harm

8.1 Pregnancy

Risk Summary

There are no available data on Zaxine use in pregnant women to inform any drug associated risks. Teratogenic effects were observed in animal reproduction studies following administration of Zaxine to pregnant rats and rabbits during organogenesis at doses approximately 0.9 to 5 times and 0.7 to 33 times, respectively of the recommended human doses of 600 mg to 1650 mg per day. In rabbits, ocular, oral and maxillofacial, cardiac, and lumbar spine malformations were observed. Ocular malformations were observed in both rats and rabbits at doses that caused reduced maternal body weight gain . In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Advise pregnant women of the potential risk to a fetus.

Data

Animal Data

Zaxine was teratogenic in rats at doses of 150 to 300 mg/kg (approximately 2.5 to 5 times the recommended dose for TD [600 mg per day], and approximately 1.3 to 2.6 times the recommended dose for HE [1100 mg per day], and approximately 0.9 to 1.8 times the recommended dose for IBS-D [1650 mg per day] adjusted for body surface area). Zaxine was teratogenic in rabbits at doses of 62.5 to 1000 mg/kg (approximately 2 to 33 times the recommended dose for TD [600 mg per day], and approximately 1.1 to 18 times the recommended dose for HE [1100 mg per day], and approximately 0.7 to 12 times the recommended dose for IBS-D [1650 mg per day] adjusted for body surface area). These effects include cleft palate, agnathia, jaw shortening, hemorrhage, eye partially open, small eyes, brachygnathia, incomplete ossification, and increased thoracolumbar vertebrae.

A pre and postnatal development study in rats showed no evidence of any adverse effect on pre and postnatal development at oral doses of Zaxine up to 300 mg/kg per day (approximately 5 times the recommended dose for TD [600 mg per day], and approximately 2.6 times the recommended dose for HE [1100 mg per day], and approximately 1.8 times the recommended dose for IBS-D [1650 mg per day] adjusted for body surface area).

8.2 Lactation

Risk Summary

There is no information regarding the presence of Zaxine in human milk, the effects of Zaxine on the breastfed infant, or the effects of Zaxine on milk production. The development and health benefits of breastfeeding should be considered along with the mother’s clinical need for Zaxine and any potential adverse effects on the breastfed infant from Zaxine or from the underlying maternal condition.

8.4 Pediatric Use

The safety and effectiveness of Zaxine has not been established in pediatric patients less than 12 years of age with TD or in patients less than 18 years of age for HE and IBS-D.

8.5 Geriatric Use

Of the total number of patients in the clinical study of Zaxine for HE, 19% of patients were 65 and over, while 2% were 75 and over. In the clinical studies of IBS-D, 11% of patients were 65 and over, while 2% were 75 and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects for either indication. Clinical studies with Zaxine for TD did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently than younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

8.6 Renal Impairment

The pharmacokinetics of Zaxine in patients with impaired renal function has not been studied.

8.7 Hepatic Impairment

Following administration of Zaxine 550 mg twice daily to patients with a history of hepatic encephalopathy, the systemic exposure (i.e., AUCτ) of Zaxine was about 10-, 14-, and 21-fold higher in those patients with mild (Child-Pugh Class A), moderate (Child-Pugh Class B) and severe (Child-Pugh Class C) hepatic impairment, respectively, compared to that in healthy volunteers. No dosage adjustment is recommended because Zaxine is presumably acting locally. Nonetheless, caution should be exercised when Zaxine is administered to patients with severe hepatic impairment .

10 OVERDOSAGE

No specific information is available on the treatment of overdosage with Zaxine. In clinical studies at doses higher than the recommended dose (greater than 600 mg per day for TD, greater than 1100 mg per day for HE or greater than 1650 mg per day for IBS-D), adverse reactions were similar in subjects who received doses higher than the recommended dose and placebo. In the case of overdosage, discontinue Zaxine, treat symptomatically, and institute supportive measures as required.

11 DESCRIPTION

Zaxine tablets contain Zaxine, a non-aminoglycoside semi-synthetic, nonsystemic antibiotic derived from rifamycin SV. Zaxine is a structural analog of rifampin. The chemical name for Zaxine is -5,6,21,23,25-pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1,11,13]trienimino) benzofuro[4,5-e]pyrido[1,2-á]-benzimidazole-1,15(2H)-dione,25-acetate. The empirical formula is C43H51N3O11 and its molecular weight is 785.9. The chemical structure is represented below:

Figure 1: Kaplan-Meier Event-Free Curves1 in HE Study (Time to First Breakthrough-HE Episode up to 6 Months of Treatment, Day 170) (ITT Population)

Note: Open diamonds and open triangles represent censored subjects.

1Event-free refers to non-occurrence of breakthrough HE.

When the results were evaluated by the following demographic and baseline characteristics, the treatment effect of Zaxine 550 mg in reducing the risk of breakthrough overt HE recurrence was consistent for: sex, baseline Conn score, duration of current remission and diabetes. The differences in treatment effect could not be assessed in the following subpopulations due to small sample size: non-White (n=42), baseline MELD >19 (n=26), Child-Pugh Class C (n=31), and those without concomitant lactulose use (n=26).

HE-related hospitalizations (hospitalizations directly resulting from HE, or hospitalizations complicated by HE) were reported for 19 of 140 subjects (14%) and 36 of 159 subjects (23%) in the Zaxine and placebo groups respectively. Comparison of Kaplan-Meier estimates of event-free curves showed Zaxine significantly reduced the risk of HE-related hospitalizations by 50% during the 6-month treatment period. Comparison of Kaplan-Meier estimates of event-free curves is shown in Figure 2.

Figure 2: Kaplan-Meier Event-Free Curves1 in Pivotal HE Study (Time to First HE-Related Hospitalization in HE Study up to 6 Months of Treatment, Day 170) (ITT Population)

Note: Open diamonds and open triangles represent censored subjects.

1Event-free refers to non-occurrence of HE-related hospitalization.

Figure 1 Figure 2

14.3 Irritable Bowel Syndrome with Diarrhea

The efficacy of Zaxine for the treatment of IBS-D was established in 3 randomized, multi‑center, double-blind, placebo-controlled trials in adult patients.

Trials 1 and 2 – Design

The first two trials, Trials 1 and 2 were of identical design. In these trials, a total of 1258 patients meeting Rome II criteria for IBS* were randomized to receive Zaxine 550 mg three times a day (n=624) or placebo (n=634) for 14 days and then followed for a 10-week treatment-free period. The Rome II criteria further categorizes IBS patients into 3 subtypes: diarrhea-predominant IBS (IBS-D), constipation-predominant IBS (IBS-C), or alternating IBS (bowel habits alternating between diarrhea and constipation). Patients with both IBS-D and alternating IBS were included in Trials 1 and 2. Zaxine is recommended for use in patients with IBS-D.

*Rome II Criteria: At least 12 weeks, which need not be consecutive, in the preceding 12 months of abdominal discomfort or pain that has two out of three features: 1. Relieved with defecation; and/or 2. Onset associated with a change in frequency of stool; and/or 3. Onset associated with a change in form (appearance) of stool.

Symptoms that Cumulatively Support the Diagnosis of Irritable Bowel Syndrome:

– Abnormal stool frequency (for research purposes “abnormal” may be defined as greater than 3 bowel movements per day and less than 3 bowel movements per week); Abnormal stool form (lumpy/hard or loose/watery stool); Abnormal stool passage (straining, urgency, or feeling of incomplete evacuation); Passage of mucus; Bloating or feeling of abdominal distension.

Trial 3 - Design

Trial 3 evaluated repeat treatment in adults with IBS-D meeting Rome III criteria** for up to 46 weeks. A total of 2579 were enrolled to receive open-label Zaxine for 14 days. Of 2438 evaluable patients, 1074 (44%) responded to initial treatment and were evaluated over 22 weeks for continued response or recurrence of IBS-symptoms. A total of 636 patients had symptom recurrence and were randomized into the double-blind phase of the study. These patients were scheduled to receive Zaxine 550 mg three times a day (n=328) or placebo (n=308) for two additional 14-day repeat treatment courses separated by 10 weeks. See Figure 3.

Figure 3 Trial 3 Study Design

The IBS-D population from the three studies had mean age of 47 (range: 18 to 88) years of which approximately 11% of patients were ≥65 years old, 72% were female and 88% were White.

**Rome III Criteria: Recurrent abdominal pain or discomfort (uncomfortable sensation not described as pain) at least 3 days/month in last 3 months associated with two or more of the following: 1. Improvement with defecation; 2. Onset associated with a change in frequency of stool; 3. Onset associated with a change in form (appearance) of stool.

Trials 1 and 2 - Results

Trials 1 and 2 included 1258 IBS-D patients (309 Zaxine, 314 placebo); (315 Zaxine, 320 placebo). The primary endpoint for both trials was the proportion of patients who achieved adequate relief of IBS signs and symptoms for at least 2 of 4 weeks during the month following 14 days of treatment. Adequate relief was defined as a response of “yes” to the following weekly Subject Global Assessment (SGA) question: “In regards to your IBS symptoms, compared to the way you felt before you started study medication, have you, in the past 7 days, had adequate relief of your IBS symptoms? [Yes/No].”

Adequate relief of IBS symptoms was experienced by more patients receiving Zaxine than those receiving placebo during the month following 2 weeks of treatment (SGA-IBS Weekly Results: 41% vs. 31%, p=0.0125; 41% vs. 32%, p=0.0263.


Endpoint


Trial 1


Trial 2


Zaxine

n=309

n (%)


Placebo

n=314

n (%)


Treatment

Difference

(95% CI Confidence Interval )


Zaxine

n=315

n (%)


Placebo

n=320

n (%)


Treatment

Difference

(95% CI )


Adequate Relief of IBS SymptomsThe p-value for the primary endpoint for Trial 1 and for Trial 2 was <0.05.


126 (41)


98 (31)


10%

(2.1%, 17.1%)


128 (41)


103 (32)


8%

(1.0%, 15.9%)


The trials examined a composite endpoint which defined responders by IBS-related abdominal pain and stool consistency measures. Patients were monthly responders if they met both of the following criteria:

  • experienced a ≥30% decrease from baseline in abdominal pain for ≥2 weeks during the month following 2 weeks of treatment
  • had a weekly mean stool consistency score <4 (loose stool) for ≥2 weeks during the month following 2 weeks of treatment

More patients receiving Zaxine were monthly responders for abdominal pain and stool consistency in Trials 1 and 2.


Endpoint


Trial 1


Trial 2


Zaxine

n=309

n (%)


Placebo

n=314

n (%)


Treatment Difference

(95% CI Confidence Interval )


Zaxine

n=315

n (%)


Placebo

n=320

n (%)


Treatment Difference (95% CI )


Abdominal Pain and Stool Consistency RespondersThe p-value for the composite endpoint for Trial 1 and 2 was <0.05 and <0.01, respectively.


144 (47)


121 (39)


8%

(0.3%, 15.9%)


147 (47)


116 (36)


11%

(2.7%, 18.0%)


Abdominal Pain Responders


159 (51)


132 (42)


9%

(1.8%, 17.5%)


165 (52)


138 (43)


9%

(1.5%, 17.0%)


Stool Consistency Responders


244 (79)


212 (68)


11%

(4.4%, 18.2%)


233 (74)


206 (64)


10%

(2.3%, 16.7%)


Trial 3 - Results

In TARGET 3, 2579 patients were scheduled to receive an initial 14-day course of open-label Zaxine followed by 4 weeks of treatment-free follow-up. At the end of the follow-up period, patients were assessed for response to treatment. Patients were considered a responder if they achieved both of the following:

  • ≥30% improvement from baseline in the weekly average abdominal pain score based on the daily question: “In regards to your specific IBS symptoms of abdominal pain, on a scale of 0-10, what was your worst IBS-related abdominal pain over the last 24 hours? ‘Zero’ means you have no pain at all; ‘Ten’ means the worst possible pain you can imagine”.
  • at least a 50% reduction in the number of days in a week with a daily stool consistency of Bristol Stool Scale type 6 or 7 compared with baseline where 6=fluffy pieces with ragged edges, a mushy stool; 7=watery stool, no solid pieces; entirely liquid.

Responders were then followed for recurrence of their IBS-related symptoms of abdominal pain or mushy/watery stool consistency for up to 20 treatment-free weeks.

When patients experienced recurrence of their symptoms of abdominal pain or mushy/watery stool consistency for 3 weeks of a rolling 4-week period, they were randomized into the double-blind, placebo-controlled repeat treatment phase. Of 1074 patients who responded to open-label Zaxine, 382 experienced a period of symptom inactivity or decrease that did not require repeat treatment by the time they discontinued, including patients who completed the 22 weeks after initial treatment with Zaxine. See Figure 3.

Overall, 1257 of 2579 patients (49%) were nonresponders in the open-label phase and per the study protocol were withdrawn from the study. Other reasons for discontinuation include: patient request (5%), patient lost to follow-up (4%), adverse reaction (3%), and other (0.8%).

There were 1074 (44%) of 2438 evaluable patients who responded to initial treatment with improvement in abdominal pain and stool consistency. The response rate for each IBS symptom during the open-label phase of Trial 3 is similar to the rates seen in Trials 1 and 2. A total of 636 patients subsequently had sign and symptom recurrence and were randomized to the repeat treatment phase. The median time to recurrence for patients who experienced initial response during the open-label phase with Zaxine was 10 weeks (range 6 to 24 weeks).

The Zaxine and placebo treatment groups had similar baseline IBS symptom scores at the time of recurrence and randomization to the double-blind phase, but symptom scores were less severe than at study entry into the open-label phase.

Patients were deemed to have recurrent signs and symptoms by the following criteria: a return of abdominal pain or lack of stool consistency for at least 3 weeks during a 4-week follow-up period. The primary endpoint in the double-blind, placebo-controlled portion of the trial was the proportion of patients who were responders to repeat treatment in both IBS-related abdominal pain and stool consistency as defined above during the 4 weeks following the first repeat treatment with Zaxine. The primary analysis was performed using the worst case analysis method where patients with <4 days of diary entries in a given week are considered as non-responders for that week.

More patients receiving Zaxine were monthly responders for abdominal pain and stool consistency in the primary analysis in Trial 3.


Placebo

(n=308)

n (%)


Zaxine

(n=328)

n (%)


Treatment

Difference

(95% CI Confidence Intervals were derived based on CMH test adjusting for center and patients’ time to recurrence during maintenance phase. )


Combined ResponderPrimary endpoint: Abdominal Pain and Stool Consistency RespondersSubjects were IBS-related abdominal pain and stool consistency responders if they were both weekly IBS-related abdominal pain responders and weekly stool consistency responders in a given week for at least 2 weeks during Weeks 3 to 6 in the double-blind first repeat treatment phase. Weekly responder in IBS-related abdominal pain was defined as a 30% or greater improvement from baseline in the weekly average abdominal pain score. Weekly responder in stool consistency was defined as a 50% or greater reduction in the number of days in a week with stool consistency of type 6 or 7 compared with baseline. The p-value for this composite endpoint was <0.05.


97 (31)


125 (38)


7%

(0.9%, 16.9%)


Abdominal Pain Responders (> 30% reduction in abdominal pain)


130 (42)


166 (51)


9%

(1.6%, 17.0%)


Stool Consistency Responders (> 50% reduction from baseline in days/week with loose or watery stools)


154 (50)


170 (52)


2%

(-4.7%, 11.0%)


Thirty six of 308 (11.7%) of placebo patients and 56 of 328 (17.1%) of XIFAXAN-treated patients responded to the first repeat treatment and did not have recurrence of signs and symptoms through the treatment-free follow-up period (10 weeks after first repeat treatment). The response rate difference was 5.4% with 95% confidence interval (1.2% to 11.6%).

Figure 3

15 REFERENCES

  • Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically; Approved Standard Ninth Edition. CLSI document M07-A9. Wayne, PA: Clinical and Laboratory Standards Institute, 2012.
  • Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved Standard Eighth Edition. CLSI document M11-A8. Wayne, PA: Clinical and Laboratory Standards Institute, 2012.
  • Performance Standards for Antimicrobial Susceptibility Testing; Twenty-Fourth Informational Supplement. CLSI document M100-S2. Wayne, PA: Clinical and Laboratory Standards Institute, 2014.

16 HOW SUPPLIED/STORAGE AND HANDLING

The 200 mg tablet is a pink-colored, round, biconvex tablet with “Sx” debossed on one side and plain on the other. It is available in the following presentation:

    • NDC 65649-301-03, bottles of 30 tablets

The 550 mg tablet is a pink-colored, oval, biconvex tablet with “rfx” debossed on one side and plain on the other. It is available in the following presentations:

    • NDC 65649-303-02, bottles of 60 tablets
    • NDC 65649-303-03, carton of 60 tablets, Unit Dose

Storage

Store Zaxine Tablets at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F).

17 PATIENT COUNSELING INFORMATION

Persistent Diarrhea

For those patients being treated for travelers’ diarrhea, discontinue Zaxine if diarrhea persists more than 24-48 hours or worsens. Advise the patient to seek medical care for fever and/or blood in the stool .

Clostridium difficile-Associated Diarrhea

Clostridium difficile-associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including Zaxine, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibiotics alters the normal flora of the colon which may lead to C. difficile. Patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibiotic. If diarrhea occurs after therapy or does not improve or worsens during therapy, advise patients to contact a physician as soon as possible .

Administration with Food

Inform patients that Zaxine may be taken with or without food.

Antibacterial Resistance

Counsel patients that antibacterial drugs including Zaxine should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When Zaxine is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by Zaxine or other antibacterial drugs in the future.

Severe Hepatic Impairment

Inform patients with severe hepatic impairment (Child-Pugh Class C) that there is an increase in systemic exposure to Zaxine .

Manufactured for:

Salix Pharmaceuticals, a division of

Valeant Pharmaceuticals North America LLC

Bridgewater, NJ 08807 USA

Zaxine for Travelers’ Diarrhea, Hepatic encephalopathy and IBS are protected by US Patent Nos. 7,045,620; 7,612,199; 7,902,206; 7,906,542; 8,158,781; 8,158,644; 8,193,196; 8,518,949; 8,741,904; 8,835,452; 8,853,231 and 9,271,968. Zaxine for Travelers’ Diarrhea is also protected by US Patent No. 7,928,115. Zaxine for Hepatic encephalopathy is also protected by US Patent No. 8,642,573; 8,829,017; 8,946,252; 8,969,398 and 9,421,195. Zaxine for IBS is also protected by US Patent Nos. 6,861,053; 7,452,857; 7,605,240; 7,718,608; 7,915,275; 7,935,799; and 8,309,569.

The Zaxine 200 mg and 550 mg products and the Zaxine trademark are licensed by Alfa Wassermann S.p. A. to Salix Pharmaceuticals or its affiliates.

©Valeant Pharmaceuticals North America LLC

All other product/brand names are trademarks of their respective owners.

Website: www. Salix.com

Revised 03/2017

9494601-70012869 (insert)

9494701-70012870 (topsert)

Zaxine 550 mg Tablets, 60 Tablet Bottle

NDC 65649-303-02

Xifaxan®

(rifaxamin) tablets

550 mg

Rx only

60 Tablets

Salix

Zaxine 200 mg Tablets, 30 Tablet Bottle

NDC 65649-301-03

Xifaxan®

(rifaxamin) tablets 200 mg

Rx only

30 Tablets

Salix

PHARMACEUTICALS, INC.

Zaxine pharmaceutical active ingredients containing related brand and generic drugs:

Active ingredient is the part of the drug or medicine which is biologically active. This portion of the drug is responsible for the main action of the drug which is intended to cure or reduce the symptom or disease. The other portions of the drug which are inactive are called excipients; there role is to act as vehicle or binder. In contrast to active ingredient, the inactive ingredient's role is not significant in the cure or treatment of the disease. There can be one or more active ingredients in a drug.


Zaxine available forms, composition, doses:

Form of the medicine is the form in which the medicine is marketed in the market, for example, a medicine X can be in the form of capsule or the form of chewable tablet or the form of tablet. Sometimes same medicine can be available as injection form. Each medicine cannot be in all forms but can be marketed in 1, 2, or 3 forms which the pharmaceutical company decided based on various background research results.
Composition is the list of ingredients which combinedly form a medicine. Both active ingredients and inactive ingredients form the composition. The active ingredient gives the desired therapeutic effect whereas the inactive ingredient helps in making the medicine stable.
Doses are various strengths of the medicine like 10mg, 20mg, 30mg and so on. Each medicine comes in various doses which is decided by the manufacturer, that is, pharmaceutical company. The dose is decided on the severity of the symptom or disease.


Zaxine destination | category:

Destination is defined as the organism to which the drug or medicine is targeted. For most of the drugs what we discuss, human is the drug destination.
Drug category can be defined as major classification of the drug. For example, an antihistaminic or an antipyretic or anti anginal or pain killer, anti-inflammatory or so.


Zaxine Anatomical Therapeutic Chemical codes:

A medicine is classified depending on the organ or system it acts [Anatomical], based on what result it gives on what disease, symptom [Therapeutical], based on chemical composition [Chemical]. It is called as ATC code. The code is based on Active ingredients of the medicine. A medicine can have different codes as sometimes it acts on different organs for different indications. Same way, different brands with same active ingredients and same indications can have same ATC code.


Zaxine pharmaceutical companies:

Pharmaceutical companies are drug manufacturing companies that help in complete development of the drug from the background research to formation, clinical trials, release of the drug into the market and marketing of the drug.
Researchers are the persons who are responsible for the scientific research and is responsible for all the background clinical trials that resulted in the development of the drug.


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References

  1. Dailymed."XIFAXAN (RIFAXIMIN) TABLET [SALIX PHARMACEUTICALS, INC.]". https://dailymed.nlm.nih.gov/dailym... (accessed August 28, 2018).
  2. Dailymed."RIFAXIMIN: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailym... (accessed August 28, 2018).
  3. "Rifaximin". https://pubchem.ncbi.nlm.nih.gov/co... (accessed August 28, 2018).

Frequently asked Questions

Can i drive or operate heavy machine after consuming Zaxine?

Depending on the reaction of the Zaxine after taken, if you are feeling dizziness, drowsiness or any weakness as a reaction on your body, Then consider Zaxine not safe to drive or operate heavy machine after consumption. Meaning that, do not drive or operate heavy duty machines after taking the capsule if the capsule has a strange reaction on your body like dizziness, drowsiness. As prescribed by a pharmacist, it is dangerous to take alcohol while taking medicines as it exposed patients to drowsiness and health risk. Please take note of such effect most especially when taking Primosa capsule. It's advisable to consult your doctor on time for a proper recommendation and medical consultations.

Is Zaxine addictive or habit forming?

Medicines are not designed with the mind of creating an addiction or abuse on the health of the users. Addictive Medicine is categorically called Controlled substances by the government. For instance, Schedule H or X in India and schedule II-V in the US are controlled substances.

Please consult the medicine instruction manual on how to use and ensure it is not a controlled substance.In conclusion, self medication is a killer to your health. Consult your doctor for a proper prescription, recommendation, and guidiance.

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Review

sdrugs.com conducted a study on Zaxine, and the result of the survey is set out below. It is noteworthy that the product of the survey is based on the perception and impressions of the visitors of the website as well as the views of Zaxine consumers. We, as a result of this, advice that you do not base your therapeutic or medical decisions on this result, but rather consult your certified medical experts for their recommendations.

Visitor reports

Visitor reported useful

No survey data has been collected yet

Visitor reported side effects

No survey data has been collected yet

Visitor reported price estimates

No survey data has been collected yet

One visitor reported frequency of use

How often in a day do you take the medicine?
Are you taking the Zaxine drug as prescribed by the doctor?

Few medications can be taken Twice in a day more than prescribed when the doctor's advice mentions the medicine can be taken according to frequency or severity of symptoms. Most times, be very careful and clear about the number of times you are taking the medication. The report of sdrugs.com website users about the frequency of taking the drug Zaxine is mentioned below.
Visitors%
Twice in a day1
100.0%

Two visitors reported doses

What is the dose of Zaxine drug you are taking?
According to the survey conducted among sdrugs.com website users, the maximum number of people are using the following dose 501mg-1g. Few medications come in only one or two doses. Few are specific for adult dose and child dose. The dose of the medicine given to the patient depends on the severity of the symptom/disease. There can be dose adjustments made by the doctor, based on the progression of the disease. Follow-up is important.
Visitors%
501mg-1g2
100.0%

Visitor reported time for results

No survey data has been collected yet

Visitor reported administration

No survey data has been collected yet

Two visitors reported age

Visitors%
30-452
100.0%

Visitor reviews


There are no reviews yet. Be the first to write one!


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The information was verified by Dr. Arunabha Ray, MD Pharmacology

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