Ribasphere

Tell your healthcare provider if you are breastfeeding. It is not known if Ribasphere passes into your breast milk. You and your healthcare provider should decide if you will take Ribasphere or breastfeed.

Ribasphere monotherapy is not effective for the treatment of chronic hepatitis C virus infection and should not be used alone for this indication.The primary toxicity of Ribasphere is hemolytic anemia. The anemia associated with Ribasphere therapy may result in worsening of cardiac disease that has led to fatal and nonfatal myocardial infarctions. Patients with a history of significant or unstable cardiac disease should not be treated with Ribasphere.Significant teratogenic and embryocidal effects have been demonstrated in all animal species exposed to Ribasphere. In addition, ribavirin has a multiple-dose half-life of 12 days, and so it may persist in nonplasma compartments for as long as 6 months. Therefore, Ribasphere therapy is contraindicated in women who are pregnant and in the male partners of women who are pregnant. Extreme care must be taken to avoid pregnancy during therapy and for 6 months after completion of treatment in both female patients and in female partners of male patients who are taking Ribasphere therapy. At least two reliable forms of effective contraception must be utilized during treatment and during the 6-month post-treatment follow-up period.

Ribavirin is an antiviral medication.

Ribavirin must be used together with an interferon alfa product (such as Pegasys, PegIntron, Sylatron, or Intron A) to treat chronic hepatitis C.

Ribavirin may also be used for purposes not listed in this medication guide.

Avoid drinking alcohol. It may increase your risk of liver damage.

Using this medicine will not prevent you from passing hepatitis to other people. Follow your doctor's instructions about how to prevent passing the disease to another person.

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Ribavirin can cause anemia. In rare cases, this can lead to fatal heart problems. Get emergency medical attention if you have chest pain.

Call your doctor at once if you have:

• problems with your vision;

• severe pain in your upper stomach spreading to your back, nausea, vomiting, diarrhea;

• stabbing chest pain, wheezing, feeling short of breath;

• severe depression, thoughts about suicide, or thoughts about hurting someone else;

• signs of serious anemia--pale or yellowed skin, dark colored urine, confusion or weakness; or

• other signs of low blood cell counts--fever, chills, flu-like symptoms, swollen gums, mouth sores, skin sores, easy bruising, unusual bleeding, feeling light-headed.

Common side effects may include:

• nausea, flu-like symptoms, tiredness;

• fever, chills or shaking;

• headache;

• mood changes, feeling irritable;

• muscle pain; or

• stomach pain, vomiting, loss of appetite.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Pregnancy

Teratogenic Effects

Pregnancy Category X

[See Contraindications (4), Warnings and Precautions (5.1), and Nonclinical Toxicology (13.1)].

Treatment and Post-treatment:

Potential Risk to the Fetus:

Ribavirin is known to accumulate in intracellular components from where it is cleared very slowly. It is not known whether ribavirin contained in sperm will exert a potential teratogenic effect upon fertilization of the ova. In a study in rats, it was concluded that dominant lethality was not induced by ribavirin at doses up to 200 mg/kg for 5 days (estimated human equivalent doses of 7.14 to 28.6 mg/kg, based on body surface area adjustment for a 60 kg adult; up to 1.7 times the maximum recommended human dose of ribavirin). However, because of the potential human teratogenic effects of ribavirin, male patients should be advised to take every precaution to avoid risk of pregnancy for their female partners.

Women of childbearing potential should not receive Ribasphere unless they are using effective contraception (two reliable forms) during the therapy period. In addition, effective contraception should be utilized for 6 months post-therapy based on a multiple-dose half-life (t1/2) of ribavirin of 12 days.

Male patients and their female partners must practice effective contraception (two reliable forms) during treatment with Ribasphere and for the 6-month post-therapy period (e.g., 15 half-lives for ribavirin clearance from the body).

A Ribavirin Pregnancy Registry has been established to monitor maternal-fetal outcomes of pregnancies in female patients and female partners of male patients exposed to ribavirin during treatment and for 6 months following cessation of treatment. Physicians and patients are encouraged to report such cases by calling 1-800-593-2214.

Nursing Mothers

It is not known whether the Ribasphere product is excreted in human milk. Because of the potential for serious adverse reactions from the drug in nursing infants, a decision should be made whether to discontinue nursing or to delay or discontinue Ribasphere.

Pediatric Use

Safety and effectiveness of Ribasphere in combination with peginterferon alfa-2b has not been established in pediatric patients below the age of 3 years. For treatment with ribavirin/interferon alfa-2b, evidence of disease progression, such as hepatic inflammation and fibrosis, as well as prognostic factors for response, HCV genotype and viral load should be considered when deciding to treat a pediatric patient. The benefits of treatment should be weighed against the safety findings observed.

Long-term follow-up data in pediatric subjects indicates that ribavirin in combination with peginterferon alfa-2b or with interferon alfa-2b may induce a growth inhibition that results in reduced height in some patients [see Warnings and Precautions (5.9) and Adverse Reactions (6.1, 6.2)].

Suicidal ideation or attempts occurred more frequently among pediatric patients, primarily adolescents, compared to adult patients (2.4% vs. 1%) during treatment and off-therapy follow-up [see Warnings and Precautions (5.10)]. As in adult patients, pediatric patients experienced other psychiatric adverse reactions (e.g., depression, emotional lability, somnolence), anemia, and neutropenia [see Warnings and Precautions (5.2)].

Geriatric Use

Clinical trials of ribavirin/interferon alfa-2b or peginterferon alfa-2b therapy did not include sufficient numbers of subjects aged 65 and over to determine if they respond differently from younger subjects.

Ribavirin is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients often have decreased renal function, care should be taken in dose selection. Renal function should be monitored and dosage adjustments should be made accordingly. Ribasphere should not be used in patients with creatinine clearance less than 50 mL/min [see Contraindications (4)].

In general, Ribasphere capsules should be administered to elderly patients cautiously, starting at the lower end of the dosing range, reflecting the greater frequency of decreased hepatic and cardiac function, and of concomitant disease or other drug therapy. In clinical trials, elderly subjects had a higher frequency of anemia (67%) than younger patients (28%) [see Warnings and Precautions (5.2)].

Organ Transplant Recipients

The safety and efficacy of interferon alfa-2b and peginterferon alfa-2b alone or in combination with Ribasphere for the treatment of hepatitis C in liver or other organ transplant recipients have not been established. In a small (n=16) single-center, uncontrolled case experience, renal failure in renal allograft recipients receiving interferon alpha and ribavirin combination therapy was more frequent than expected from the center’s previous experience with renal allograft recipients not receiving combination therapy. The relationship of the renal failure to renal allograft rejection is not clear.

HIV or HBV Co-infection

The safety and efficacy of peginterferon alfa-2b/Ribasphere and interferon alfa-2b/Ribasphere for the treatment of patients with HCV co-infected with HIV or HBV have not been established.

There is limited experience with overdosage. Acute ingestion of up to 20 g of ribavirin capsules, interferon alfa-2b ingestion of up to 120 million units, and subcutaneous doses of interferon alfa-2b up to 10 times the recommended doses have been reported. Primary effects that have been observed are increased incidence and severity of the adverse reactions related to the therapeutic use of interferon alfa-2b and ribavirin. However, hepatic enzyme abnormalities, renal failure, hemorrhage, and myocardial infarction have been reported with administration of single subcutaneous doses of interferon alfa-2b that exceed dosing recommendations.

There is no specific antidote for interferon alfa-2b or Ribasphere overdose, and hemodialysis and peritoneal dialysis are not effective for treatment of overdose of these agents.

Ribasphere® (ribavirin capsules USP) is a synthetic nucleoside analogue (purine analogue). The chemical name of ribavirin is 1-ß-D-ribofuranosyl-1 H-1,2,4-triazole-3-carboxamide and has the following structural formula (see Figure 1):

Figure 1: Structural Formula

Ribavirin is a white, crystalline powder. It is freely soluble in water and slightly soluble in anhydrous alcohol. The empirical formula is C 8H12N4O5 and the molecular weight is 244.21.

Ribasphere® (ribavirin capsules USP) consists of white pellets in a white, opaque, gelatin capsule. Each capsule contains 200 mg ribavirin and the inactive ingredients: Croscarmellose Sodium, NF, Lactose Monohydrate, NF, Microcrystalline Cellulose, NF, and Povidone, USP. The capsule shell consists of gelatin and titanium dioxide. The capsule is printed horizontally with "riba 200" on both the body and the cap of the capsule using edible, green pharmaceutical ink which is made of butyl alcohol, NF, Yellow Iron Oxide, NF, dehydrated alcohol, USP, FD&C Blue #2 Aluminum Lake, isopropyl alcohol, USP, propylene glycol, USP, Shellac, NF, strong ammonia solution, NF, and titanium dioxide.

Clinical Study 1 evaluated peginterferon alfa-2b monotherapy. See peginterferon alfa-2b labeling for information about this trial.

Ribavirin/Peginterferon alfa-2b Combination Therapy

Adult Subjects

Study 2

A randomized trial compared treatment with two peginterferon alfa-2b/ribavirin regimens [peginterferon alfa-2b 1.5 mcg/kg subcutaneously once weekly/ribavirin 800 mg orally daily (in divided doses); peginterferon alfa-2b 1.5 mcg/kg subcutaneously once weekly for 4 weeks then 0.5 mcg/kg subcutaneously once weekly for 44 weeks/ribavirin 1000 or 1200 mg orally daily (in divided doses)] with interferon alfa-2b [3 MIU subcutaneously three times weekly/ribavirin 1000 or 1200 mg orally daily (in divided doses)] in 1530 adults with chronic hepatitis C. Interferon-naïve subjects were treated for 48 weeks and followed for 24 weeks post-treatment. Eligible subjects had compensated liver disease, detectable HCV-RNA, elevated ALT, and liver histopathology consistent with chronic hepatitis.

Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment (see Table 13). The response rate to the peginterferon alfa-2b 1.5 mcg/kg and ribavirin 800 mg dose was higher than the response rate to interferon alfa-2b/ribavirin (see Table 13).

The response rate to peginterferon alfa-2b 1.5→0.5 mcg/kg/ribavirin was essentially the same as the response to interferon alfa-2b/ribavirin (data not shown).

Table 13: Rates of Response to Combination Treatment - Study 2

* Serum HCV-RNA was measured with a research-based quantitative polymerase chain reaction assay by a central laboratory. † Difference in overall treatment response (peginterferon alfa-2b/ribavirin vs. interferon alfa-2b/ribavirin) is 6% with 95% confidence interval of (0.18, 11.63) adjusted for viral genotype and presence of cirrhosis at baseline. Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment.
	Peginterferon alfa-2b 1.5 mcg/kg once weekly    Ribavirin 800 mg once daily	Interferon alfa-2b 3 MIU three times weekly    Ribavirin 1000/1200 mg once daily
Overall response*,†	52% (264/511)	46% (231/505)
Genotype 1	41% (141/348)	33% (112/343)
Genotype 2-6	75% (123/163)	73% (119/162)

Subjects with viral genotype 1, regardless of viral load, had a lower response rate to peginterferon alfa-2b (1.5 mcg/kg)/ribavirin (800 mg) compared to subjects with other viral genotypes. Subjects with both poor prognostic factors (genotype 1 and high viral load) had a response rate of 30% (78/256) compared to a response rate of 29% (71/247) with interferon alfa-2b/ribavirin combination therapy.

Subjects with lower body weight tended to have higher adverse-reaction rates [see Adverse Reactions (6.1)] and higher response rates than subjects with higher body weights. Differences in response rates between treatment arms did not substantially vary with body weight.

Treatment response rates with peginterferon alfa-2b/ribavirin combination therapy were 49% in men and 56% in women. Response rates were lower in African American and Hispanic subjects and higher in Asians compared to Caucasians. Although African Americans had a higher proportion of poor prognostic factors compared to Caucasians, the number of non-Caucasians studied (11% of the total) was insufficient to allow meaningful conclusions about differences in response rates after adjusting for prognostic factors in this trial.

Liver biopsies were obtained before and after treatment in 68% of subjects. Compared to baseline, approximately two-thirds of subjects in all treatment groups were observed to have a modest reduction in inflammation.

Study 3

In a large United States community-based trial, 4913 subjects with chronic hepatitis C were randomized to receive peginterferon alfa-2b 1.5 mcg/kg subcutaneously once weekly in combination with a ribavirin dose of 800 to 1400 mg (weight-based dosing [WBD]) or 800 mg (flat) orally daily (in divided doses) for 24 or 48 weeks based on genotype. Response to treatment was defined as undetectable HCV-RNA (based on an assay with a lower limit of detection of 125 IU/mL) at 24 weeks post-treatment.

Treatment with peginterferon alfa-2b 1.5 mcg/kg and ribavirin 800 to 1400 mg resulted in a higher sustained virologic response compared to peginterferon alfa-2b in combination with a flat 800 mg daily dose of ribavirin. Subjects weighing greater than 105 kg obtained the greatest benefit with WBD, although a modest benefit was also observed in subjects weighing greater than 85 to 105 kg (see Table 14). The benefit of WBD in subjects weighing greater than 85 kg was observed with HCV genotypes 1-3. Insufficient data were available to reach conclusions regarding other genotypes. Use of WBD resulted in an increased incidence of anemia [see Adverse Reactions (6.1)].

Table 14: SVR Rate by Treatment and Baseline Weight - Study 3

* P=0.01, primary efficacy comparison (based on data from subjects weighing 65 kg or higher at baseline and utilizing a logistic regression analysis that includes treatment [WBD or Flat], genotype and presence/absence of advanced fibrosis, in the model).
Treatment Group	Subject Baseline Weight
	<65 kg (<143 lb)	65-85 kg (143-188 lb)	>85-105 kg (>188-231 lb)	>105 kg (>231 lb)
WBD*	50% (173/348)	45% (449/994)	42% (351/835)	47% (138/292)
Flat	51% (173/342)	44% (443/1011)	39% (318/819)	33% (91/272)

A total of 1552 subjects weighing greater than 65 kg in Study 3 had genotype 2 or 3 and were randomized to 24 or 48 weeks of therapy. No additional benefit was observed with the longer treatment duration.

Study 4

A large randomized trial compared the safety and efficacy of treatment for 48 weeks with two peginterferon alfa-2b/ribavirin regimens [peginterferon alfa-2b 1.5 mcg/kg and 1 mcg/kg subcutaneously once weekly both in combination with ribavirin 800 to 1400 mg PO daily (in two divided doses)] and peginterferon alfa-2a 180 mcg subcutaneously once weekly in combination with ribavirin tablets 1000 to 1200 mg PO daily (in two divided doses) in 3070 treatment-naïve adults with chronic hepatitis C genotype 1. In this trial, lack of early virologic response (undetectable HCV-RNA or greater than or equal to 2 log10 reduction from baseline) by treatment Week 12 was the criterion for discontinuation of treatment. SVR was defined as undetectable HCV-RNA (Roche COBAS TaqMan assay, a lower limit of quantitation of 27 IU/mL) at 24 weeks post-treatment (see Table 15).

Table 15: SVR Rate by Treatment - Study 4

% (number) of Subjects
Peginterferon alfa-2b 1.5 mcg/kg/Ribavirin capsules	Peginterferon alfa-2b 1 mcg/kg/Ribavirin capsules	Peginterferon alfa-2a 180 mcg/Ribavirin tablets
40 (406/1019)	38 (386/1016)	41 (423/1035)

Overall SVR rates were similar among the three treatment groups. Regardless of treatment group, SVR rates were lower in subjects with poor prognostic factors. Subjects with poor prognostic factors randomized to peginterferon alfa-2b (1.5 mcg/kg)/ribavirin capsules or peginterferon alfa-2a/ ribavirin tablets, however, achieved higher SVR rates compared to similar subjects randomized to peginterferon alfa-2b 1 mcg/kg/ribavirin capsules. For the peginterferon alfa-2b 1.5 mcg/kg and ribavirin capsules dose, SVR rates for subjects with and without the following prognostic factors were as follows: cirrhosis (10% vs. 42%), normal ALT levels (32% vs. 42%), baseline viral load greater than 600,000 IU/mL (35% vs. 61%), 40 years of age and older (38% vs. 50%), and African American race (23% vs. 44%). In subjects with undetectable HCV-RNA at treatment Week 12 who received peginterferon alfa-2b (1.5 mcg/kg)/ribavirin capsules, the SVR rate was 81% (328/407).

Study 5 - Ribavirin/Peginterferon alfa-2b Combination Therapy in Prior Treatment Failures

In a noncomparative trial, 2293 subjects with moderate to severe fibrosis who failed previous treatment with combination alpha interferon/ribavirin were re-treated with peginterferon alfa-2b, 1.5 mcg/kg subcutaneously, once weekly, in combination with weight adjusted ribavirin. Eligible subjects included prior nonresponders (subjects who were HCV-RNA positive at the end of a minimum 12 weeks of treatment) and prior relapsers (subjects who were HCV-RNA negative at the end of a minimum 12 weeks of treatment and subsequently relapsed after post-treatment follow-up). Subjects who were negative at Week 12 were treated for 48 weeks and followed for 24 weeks post-treatment. Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment (measured using a research-based test, limit of detection 125 IU/mL). The overall response rate was 22% (497/2293) (99% CI: 19.5, 23.9). Subjects with the following characteristics were less likely to benefit from re-treatment: previous nonresponse, previous pegylated interferon treatment, significant bridging fibrosis or cirrhosis, and genotype 1 infection.

The re-treatment sustained virologic response rates by baseline characteristics are summarized in Table 16.

Table 16: SVR Rates by Baseline Characteristics of Prior Treatment Failures -Study 5

HCV Genotype/ Metavir Fibrosis Score	Overall SVR by Previous Response and Treatment
	Nonresponder		Relapser
	interferon alfa/ ribavirin % (number of subjects)	peginterferon (2a and 2b combined)/ ribavirin % (number of subjects)	interferon alfa/ ribavirin % (number of subjects)	peginterferon (2a and 2b combined)/ ribavirin % (number of subjects)
Overall	18 (158/903)	6 (30/476)	43 (130/300)	35 (113/344)
HCV 1	13 (98/761)	4 (19/431)	32 (67/208)	23 (56/243)
F2	18 (36/202)	6 (7/117)	42 (33/79)	32 (23/72)
F3	16 (38/233)	4 (4/112)	28 (16/58)	21 (14/67)
F4	7 (24/325)	4 (8/202)	26 (18/70)	18 (19/104)
HCV 2/3	49 (53/109)	36 (10/28)	67 (54/81)	57 (52/92)
F2	68 (23/34)	56 (5/9)	76 (19/25)	61 (11/18)
F3	39 (11/28)	38 (3/8)	67 (18/27)	62 (18/29)
F4	40 (19/47)	18 (2/11)	59 (17/29)	51 (23/45)
HCV 4	17 (5/29)	7 (1/15)	88 (7/8)	50 (4/8)

Achievement of an undetectable HCV-RNA at treatment Week 12 was a strong predictor of SVR. In this trial, 1470 (64%) subjects did not achieve an undetectable HCV-RNA at treatment Week 12, and were offered enrollment into long-term treatment trials, due to an inadequate treatment response. Of the 823 (36%) subjects who were HCV-RNA undetectable at treatment Week 12, those infected with genotype 1 had an SVR of 48% (245/507), with a range of responses by fibrosis scores (F4-F2) of 39-55%. Subjects infected with genotype 2/3 who were HCV-RNA undetectable at treatment Week 12 had an overall SVR of 70% (196/281), with a range of responses by fibrosis scores (F4-F2) of 60-83%. For all genotypes, higher fibrosis scores were associated with a decreased likelihood of achieving SVR.

Pediatric Subjects

Previously untreated pediatric subjects 3 to 17 years of age with compensated chronic hepatitis C and detectable HCV-RNA were treated with ribavirin 15 mg/kg per day and peginterferon alfa-2b 60 mcg/m2 once weekly for 24 or 48 weeks based on HCV genotype and baseline viral load. All subjects were to be followed for 24 weeks post-treatment. A total of 107 subjects received treatment, of which 52% were female, 89% were Caucasian, and 67% were infected with HCV Genotype 1. Subjects infected with Genotypes 1, 4 or Genotype 3 with HCV-RNA greater than or equal to 600,000 IU/mL received 48 weeks of therapy while those infected with Genotype 2 or Genotype 3 with HCV-RNA less than 600,000 IU/mL received 24 weeks of therapy. The trial results are summarized in Table 17.

Table 17: Sustained Virologic Response Rates by Genotype and Assigned Treatment Duration - Pediatric Trial

* Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment. † N = number of responders/number of subjects with given genotype, and assigned treatment duration. ‡ Subjects with genotype 3 low viral load (less than 600,000 IU/mL) were to receive 24 weeks of treatment while those with genotype 3 and high viral load were to receive 48 weeks of treatment.
Genotype	All Subjects N = 107
	24 Weeks	48 Weeks
	Virologic Response    N*,† (%)	Virologic Response    N*,† (%)
All	26/27 (96.3)	44/80 (55.0)
1	-	38/72 (52.8)
2	14/15 (93.3)	-
3‡	12/12 (100)	2/3 (66.7)
4	-	4/5 (80.0)

Ribavirin/Interferon alfa-2b Combination Therapy

Adult Subjects

Previously Untreated Subjects

Adults with compensated chronic hepatitis C and detectable HCV-RNA (assessed by a central laboratory using a research-based RT-PCR assay) who were previously untreated with alpha interferon therapy were enrolled into two multicenter, double-blind trials (US and international) and randomized to receive ribavirin capsules 1200 mg/day (1000 mg/day for subjects weighing less than or equal to 75 kg) and interferon alfa-2b 3 MIU three times weekly or interferon alfa-2b and placebo for 24 or 48 weeks followed by 24 weeks of off-therapy follow-up. The international trial did not contain a 24-week interferon alfa-2b and placebo treatment arm. The US trial enrolled 912 subjects who, at baseline, were 67% male, 89% Caucasian with a mean Knodell HAI score (I+II+III) of 7.5, and 72% genotype 1. The international trial, conducted in Europe, Israel, Canada, and Australia, enrolled 799 subjects (65% male, 95% Caucasian, mean Knodell score 6.8, and 58% genotype 1).

Trial results are summarized in Table 18.

Table 18: Virologic and Histologic Responses: Previously Untreated Subjects*

* Number (%) of subjects. † Defined as HCV-RNA below limit of detection using a research-based RT-PCR assay at end of treatment and during follow-up period. ‡ Defined as post-treatment (end of follow-up) minus pretreatment liver biopsy Knodell HAI score (I+II+III) improvement of greater than or equal to 2 points.
	US Trial				International Trial
	24 weeks of treatment		48 weeks of treatment		24 weeks of treatment	48 weeks of treatment
	Interferon alfa-2b/ Ribavirin (N=228)	Interferon alfa-2b/ Placebo (N=231)	Interferon alfa-2b/ Ribavirin (N=228)	Interferon alfa-2b/ Placebo (N=225)	Interferon alfa-2b/ Ribavirin (N=265)	Interferon alfa-2b/ Ribavirin (N=268)	Interferon alfa-2b/ Placebo (N=266)
Virologic Response
Responder†	65 (29)	13 (6)	85 (37)	27 (12)	86 (32)	113 (42)	46 (17)
Nonresponder	147 (64)	194 (84)	110 (48)	168 (75)	158 (60)	120 (45)	196 (74)
Missing Data	16 (7)	24 (10)	33 (14)	30 (13)	21 (8)	35 (13)	24 (9)
Histologic Response
Improvement‡	102 (45)	77 (33)	96 (42)	65 (29)	103 (39)	102 (38)	69 (26)
No improvement	77 (34)	99 (43)	61 (27)	93 (41)	85 (32)	58 (22)	111 (41)
Missing Data	49 (21)	55 (24)	71 (31)	67 (30)	77 (29)	108 (40)	86 (32)

Of subjects who had not achieved HCV-RNA below the limit of detection of the research-based assay by Week 24 of ribavirin/interferon alfa-2b treatment, less than 5% responded to an additional 24 weeks of combination treatment.

Among subjects with HCV Genotype 1 treated with ribavirin/interferon alfa-2b therapy who achieved HCV-RNA below the detection limit of the research-based assay by 24 weeks, those randomized to 48 weeks of treatment had higher virologic responses compared to those in the 24-week treatment group. There was no observed increase in response rates for subjects with HCV non-genotype 1 randomized to ribavirin/interferon alfa-2b therapy for 48 weeks compared to 24 weeks.

Relapse Subjects

Subjects with compensated chronic hepatitis C and detectable HCV-RNA (assessed by a central laboratory using a research-based RT-PCR assay) who had relapsed following one or two courses of interferon therapy (defined as abnormal serum ALT levels) were enrolled into two multicenter, double-blind trials (US and international) and randomized to receive ribavirin 1200 mg/day (1000 mg/day for subjects weighing ≤ 75 kg) and interferon alfa-2b 3 MIU three times weekly or interferon alfa-2b and placebo for 24 weeks followed by 24 weeks of off-therapy follow-up. The US trial enrolled 153 subjects who, at baseline, were 67% male, 92% Caucasian with a mean Knodell HAI score (I+II+III) of 6.8, and 58% genotype 1. The international trial, conducted in Europe, Israel, Canada, and Australia, enrolled 192 subjects (64% male, 95% Caucasian, mean Knodell score 6.6, and 56% genotype 1). Trial results are summarized in Table 19.

Table 19: Virologic and Histologic Responses: Relapse Subjects*

* Number (%) of subjects. † Defined as HCV-RNA below limit of detection using a research-based RT-PCR assay at end of treatment and during follow-up period. ‡ Defined as post-treatment (end of follow-up) minus pretreatment liver biopsy Knodell HAI score (I+II+III) improvement of greater than or equal to 2 points.
	US Trial		International Trial
	Interferon alfa-2b/ Ribavirin (N=77)	Interferon alfa-2b/ Placebo (N=76)	Interferon alfa-2b/ Ribavirin (N=96)	Interferon alfa-2b/ Placebo (N=96)
Virologic Response
Responder†	33 (43)	3 (4)	46 (48)	5 (5)
Nonresponder	36 (47)	66 (87)	45 (47)	91 (95)
Missing Data	8 (10)	7 (9)	5 (5)	0 (0)
Histologic Response
Improvement‡	38 (49)	27 (36)	49 (51)	30 (31)
No improvement	23 (30)	37 (49)	29 (30)	44 (46)
Missing Data	16 (21)	12 (16)	18 (19)	22 (23)

Virologic and histologic responses were similar among male and female subjects in both the previously untreated and relapse trials.

Pediatric Subjects

Pediatric subjects 3 to 16 years of age with compensated chronic hepatitis C and detectable HCV-RNA (assessed by a central laboratory using a research-based RT-PCR assay) were treated with ribavirin 15 mg/kg per day and interferon alfa-2b 3 MIU/m2 three times weekly for 48 weeks followed by 24 weeks of off-therapy follow-up. A total of 118 subjects received treatment, of which 57% were male, 80% Caucasian, and 78% genotype 1. Subjects less than 5 years of age received ribavirin oral solution and those 5 years of age or older received either ribavirin oral solution or capsules.

Trial results are summarized in Table 20.

Table 20: Virologic Response: Previously Untreated Pediatric Subjects*

* Number (%) of subjects. † Defined as HCV-RNA below limit of detection using a research-based RT-PCR assay at end of treatment and during follow-up period.
	Interferon alfa-2b 3 MIU/m2 three times weekly/ Ribavirin 15 mg/kg/day
Overall Response† (N=118)	54 (46)
Genotype 1 (N=92)	33 (36)
Genotype non-1 (N=26)	21 (81)

Subjects with viral genotype 1, regardless of viral load, had a lower response rate to interferon alfa-2b/ribavirin combination therapy compared to subjects with genotype non-1, 36% vs. 81%. Subjects with both poor prognostic factors (genotype 1 and high viral load) had a response rate of 26% (13/50).

Ribasphere (ribavirin) is an antiviral medication.

Ribasphere must be used together with an interferon alfa product (such as Pegasys, PegIntron, Sylatron, or Intron A) to treat chronic hepatitis C.

Ribasphere may also be used for purposes not listed in this medication guide.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Applies to ribavirin: oral capsule, oral solution, oral tablet

Other dosage forms:

• inhalation powder for solution

Along with its needed effects, ribavirin (the active ingredient contained in Ribasphere) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking ribavirin:

More common

• Anxiety
• black, tarry stools
• body aches or pain
• chest pain
• congestion
• cough or hoarseness
• crying
• depersonalization
• diarrhea
• difficult or labored breathing
• discouragement
• dry mouth
• dryness of the throat
• dysphoria
• euphoria
• feeling sad or empty
• feeling unusually cold
• fever or chills
• general feeling of discomfort or illness
• headache
• hyperventilation
• irregular heartbeats
• irritability
• joint pain
• lack of appetite
• loss of interest or pleasure
• lower back or side pain
• mental depression
• muscle aches and pains
• nausea
• nervousness
• painful or difficult urination
• pale skin
• paranoia
• poor concentration
• quick to react or overreact emotionally
• rapidly changing moods
• restlessness
• right upper abdominal or stomach pain
• runny nose
• shaking
• shivering
• shortness of breath
• sleeplessness
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• sweating
• tender, swollen glands in the neck
• tightness in the chest
• trouble with concentrating
• trouble with sleeping
• trouble with swallowing
• troubled breathing with exertion
• unable to sleep
• unusual bleeding or bruising
• unusual tiredness or weakness
• voice changes
• vomiting
• wheezing

Less common

• Bleeding gums
• blood in the urine or stools
• constipation
• depressed mood
• dry skin and hair
• feeling cold
• hair loss
• husky voice
• muscle cramps and stiffness
• pinpoint red spots on the skin
• right upper abdominal or stomach fullness
• slowed heartbeat
• weight gain

Incidence not known

• Blistering, flaking, or peeling of the skin

Some side effects of ribavirin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• Acid or sour stomach
• being forgetful
• belching
• blurred vision
• bone pain
• change in taste or bad, unusual, or unpleasant (after) taste
• cracked, scaly skin
• crusting, irritation, itching, or reddening of the skin
• difficulty with moving
• dizziness or lightheadedness
• feeling of constant movement of self or surroundings
• hair loss or thinning of the hair
• heartburn
• indigestion
• lack or loss of strength
• menstrual changes
• pain or tenderness around the eyes and cheekbones
• rash
• sensation of spinning
• sneezing
• stomach discomfort, upset, or pain
• stuffy nose
• swelling
• swollen joints
• weight loss

Less common

• Back pain
• burning, dry, or itching eyes
• discharge, excessive tearing
• feeling of warmth
• redness of the face, neck, arms, and occasionally, upper chest
• redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
• skin rash, encrusted, scaly, and oozing

Incidence not known

• Change in hearing
• loss of hearing