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| RIBASPHERE RibaPak

13:52 EDT 24th July 2014 | BioPortfolio

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RIBASPHERE (ribavirin, USP) monotherapy is not effective for the treatment of chronic hepatitis C virus infection and should not be used alone for this indication (see WARNINGS).

The primary clinical toxicity of ribavirin is hemolytic anemia. The anemia associated with ribavirin 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 ribavirin (see WARNINGS, ADVERSE REACTIONS, and DOSAGE AND ADMINISTRATION).

Significant teratogenic and/or embryocidal effects have been demonstrated in all animal species exposed to ribavirin. In addition, ribavirin has a multiple dose half-life of 12 days, and it may persist in non-plasma compartments for as long as 6 months. Ribavirin 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 therapy in both female patients and in female partners of male patients who are taking ribavirin therapy. At least two reliable forms of effective contraception must be utilized during treatment and during the 6-month posttreatment follow-up period (see CONTRAINDICATIONS, WARNINGS, and PRECAUTIONS: Information for Patients, and Pregnancy: Category X).

RIBASPHERE (ribavirin, USP), is a nucleoside analogue with antiviral activity. The chemical name of ribavirin is 1-β-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide and has the following structural formula:

The molecular formula of ribavirin is CHNO and the molecular weight is 244.2. Ribavirin is a white to off-white powder. It is freely soluble in water and slightly soluble in anhydrous alcohol.

RIBASPHERE (ribavirin, USP) is available as a blue-colored (shade depending on strength), capsule-shaped, film-coated tablet for oral administration. Each tablet contains 400 mg, or 600 mg of ribavirin and the following inactive ingredients: microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, povidone K27-33, magnesium stearate, and purified water. The coating contains partially hydrolyzed polyvinyl alcohol, titanium dioxide, polyethylene glycol 3350, talc, FD&C blue #1 [brilliant blue FCF aluminum lake], and carnauba wax.

IMAGE 236331c9-bb2f-4e9f-b90e-b0d52e1bd37e-01.jpg

Ribavirin is a synthetic nucleoside analogue. The mechanism by which the combination of ribavirin and an interferon product exerts its effects against the hepatitis C virus has not been fully established.

Multiple dose ribavirin pharmacokinetic data are available for HCV patients who received ribavirin in combination with peginterferon alfa-2a. Following administration of 1200 mg/day with food for 12 weeks mean±SD (n=39; body weight >75 kg) AUC was 25,361±7110 ng·hr/mL and C was 2748±818 ng/mL. The average time to reach C was 2 hours. Trough ribavirin plasma concentrations following 12 weeks of dosing with food were 1662±545 ng/mL in HCV infected patients who received 800 mg/day (n=89), and 2112±810 ng/mL in patients who received 1200 mg/day (n=75; body weight >75 kg).

The terminal half-life of ribavirin following administration of a single oral dose of ribavirin is about 120 to 170 hours. The total apparent clearance following administration of a single oral dose of ribavirin is about 26 L/h. There is extensive accumulation of ribavirin after multiple dosing (twice daily) such that the C at steady state was four-fold higher than that of a single dose.

Effect of Food on Absorption of Ribavirin

Bioavailability of a single oral dose of ribavirin was increased by co-administration with a high-fat meal. The absorption was slowed (T was doubled) and the AUC and C increased by 42% and 66%, respectively, when ribavirin was taken with a high-fat meal compared with fasting conditions (see PRECAUTIONS and DOSAGE AND ADMINISTRATION).

The contribution of renal and hepatic pathways to ribavirin elimination after administration of ribavirin is not known. In vitro studies indicate that ribavirin is not a substrate of CYP450 enzymes.

A pharmacokinetic study in 42 subjects demonstrated there is no clinically significant difference in ribavirin pharmacokinetics among Black (n=14), Hispanic (n=13) and Caucasian (n=15) subjects.

The pharmacokinetics of ribavirin following administration of ribavirin have not been studied in patients with renal impairment and there are limited data from clinical trials on administration of ribavirin in patients with creatinine clearance <50 mL/min. Therefore, patients with creatinine clearance <50 mL/min should not be treated with ribavirin (see WARNINGS and DOSAGE AND ADMINISTRATION).

The effect of hepatic impairment on the pharmacokinetics of ribavirin following administration of ribavirin has not been evaluated. The clinical trials of ribavirin were restricted to patients with Child-Pugh class A disease.

Pharmacokinetic evaluations in pediatric patients have not been performed.

Pharmacokinetic evaluations in elderly patients have not been performed.

Ribavirin pharmacokinetics, when corrected for weight, are similar in male and female patients.

In vitro studies indicate that ribavirin does not inhibit CYP450 enzymes.

In vitro data indicate ribavirin reduces phosphorylation of lamivudine, stavudine, and zidovudine.

In vitro, didanosine or its active metabolite (dideoxyadenosine 5’– triphosphate) is increased when didanosine is co‑administered with ribavirin, which could cause or worsen clinical toxicities (see PRECAUTIONS: Drug Interactions).

There was no effect on the pharmacokinetics of representative drugs metabolized by CYP 2C9, CYP 2C19, CYP 2D6 or CYP 3A4.

Treatment with peginterferon alfa-2a once weekly for 4 weeks in healthy subjects was associated with an inhibition of P450 1A2 and a 25% increase in theophylline AUC (see PRECAUTIONS: Drug Interactions).

The safety and effectiveness of peginterferon alfa-2a in combination with ribavirin for the treatment of hepatitis C virus infection were assessed in two randomized controlled clinical trials. All patients were adults, had compensated liver disease, detectable hepatitis C virus, liver biopsy diagnosis of chronic hepatitis, and were previously untreated with interferon. Approximately 20% of patients in both studies had compensated cirrhosis (Child-Pugh class A). Patients coinfected with HIV were excluded from these studies.

In Study NV15801 (described as Study 4 in the PEGASYS¹ Package Insert), patients were randomized to receive either peginterferon alfa-2a 180 µg sc once weekly (qw) with an oral placebo, peginterferon alfa-2a 180 µg qw with ribavirin 1000 mg po (body weight <75 kg) or 1200 mg po (body weight ≥75 kg) or REBETRON™² (interferon alfa-2b 3 MIU sc tiw plus ribavirin 1000 mg or 1200 mg po). All patients received 48 weeks of therapy followed by 24 weeks of treatment-free follow-up. Ribavirin or placebo treatment assignment was blinded. Sustained virological response was defined as undetectable (<50 IU/mL) HCV RNA on or after study week 68. Peginterferon alfa-2a in combination with ribavirin resulted in a higher SVR compared to peginterferon alfa-2a alone or interferon alfa-2b and ribavirin (Table 1). In all treatment arms, patients with viral genotype 1, regardless of viral load, had a lower response rate to peginterferon alfa-2a in combination with ribavirin compared to patients with other viral genotypes.

In Study NV15942 (described as Study 5 in the PEGASYS Package Insert), all patients received peginterferon alfa-2a 180 µg sc qw and were randomized to treatment for either 24 or 48 weeks and to a ribavirin dose of either 800 mg or 1000 mg/1200 mg (for body weight <75 kg\≥75 kg). Assignment to the four treatment arms was stratified by viral genotype and baseline HCV viral titer. Patients with genotype 1 and high viral titer (defined as >2 x 10 HCV RNA copies/mL serum) were preferentially assigned to treatment for 48 weeks.

Table 1 Sustained Virologic Response (SVR) to Combination Therapy (Study NV15801*)
Interferon alfa‑2b + Ribavirin 1000 mg or 1200 mg Peginterferon alfa‑2a + placebo Peginterferon alfa‑2a  + Ribavirin 1000 mg or 1200 mg
Difference in overall treatment response (Peginterferon alfa-2a /ribavirin – Interferon alfa-2b/ribavirin) was 9% (95% CI 2.3, 15.3). *Described as Study 4 in the PEGASYS Package Insert.
All Patients 197/444 (44%) 65/224 (29%) 241/453 (53%)
Genotype 1 103/285 (36%) 29/145 (20%) 132/298 (44%)
Genotypes 2–6 94/159 (59%) 36/79 (46%) 109/155 (70%)

HCV 1 and 4 – Irrespective of baseline viral titer, treatment for 48 weeks with peginterferon alfa-2a and 1000 mg or 1200 mg of ribavirin resulted in higher SVR (defined as undetectable HCV RNA at the end of the 24-week treatment-free follow-up period) compared to shorter treatment (24 weeks) and/or 800 mg ribavirin.

HCV 2 and 3 – Irrespective of baseline viral titer, treatment for 24 weeks with peginterferon alfa-2a and 800 mg of ribavirin resulted in a similar SVR compared to longer treatment (48 weeks) and/or 1000 mg or 1200 mg of ribavirin (see Table 2).

The numbers of patients with genotype 5 and 6 were too few to allow for meaningful assessment.

Table 2 Sustained Virologic Response as a Function of Genotype (Study NV15942*)
24 Weeks Treatment 48 Weeks Treatment
Peginterferon alfa‑2a  + Ribavirin  800 mg (N=207) Peginterferon alfa‑2a  +  Ribavirin 1000 mg or 1200 mg** (N=280) Peginterferon alfa‑2a  + Ribavirin  800 mg (N=361) Peginterferon alfa‑2a  +  Ribavirin 1000 mg or 1200 mg**
(N=436)
* Described as Study 5 in the PEGASYS Package Insert. **1000 mg for body weight <75 kg; 1200 mg for body weight ≥75 kg.
Genotype 1 29/101 (29%) 48/118 (41%) 99/250 (40%) 138/271 (51%)
Genotypes 2,3 79/96 (82%) 116/144 (81%) 75/99 (76%) 117/153 (76%)
Genotype 4 0/5 (0%) 7/12 (58%) 5/8 (63%) 9/11 (82%)

Treatment response rates are lower in patients with poor prognostic factors receiving pegylated interferon alpha therapy. In studies NV15801 and NV15942, treatment response rates were lower in patients older than 40 years (50% vs. 66%), in patients with cirrhosis (47% vs. 59%), in patients weighing over 85 kg (49% vs. 60%), and in patients with genotype 1 with high vs. low viral load (43% vs. 56%). African-American patients had lower response rates compared to Caucasians.

Paired liver biopsies were performed on approximately 20% of patients in studies NV15801 and NV15942. Modest reductions in inflammation compared to baseline were seen in all treatment groups.

In studies NV15801 and NV15942, lack of early virologic response by 12 weeks (defined as HCV RNA undetectable or >2log lower than baseline) was grounds for discontinuation of treatment. Of patients who lacked an early viral response by 12 weeks and completed a recommended course of therapy despite a protocol-defined option to discontinue therapy, 5/39 (13%) achieved an SVR. Of patients who lacked an early viral response by 24 weeks, 19 completed a full course of therapy and none achieved an SVR.

RIBASPHERE (ribavirin, USP) in combination with peginterferon alfa-2a is indicated for the treatment of adults with chronic hepatitis C virus infection who have compensated liver disease and have not been previously treated with interferon alpha. Patients in whom efficacy was demonstrated included patients with compensated liver disease and histological evidence of cirrhosis (Child-Pugh class A).

RIBASPHERE (ribavirin, USP) is contraindicated in:

RIBASPHERE (ribavirin, USP) and peginterferon alfa-2a combination therapy is contraindicated in patients with:

RIBASPHERE (ribavirin, USP) must not be used alone because ribavirin monotherapy is not effective for the treatment of chronic hepatitis C virus infection. The safety and efficacy of ribavirin have only been established when used together with peginterferon alfa-2a, recombinant.

RIBASPHERE (ribavirin, USP) and peginterferon alfa-2a should be discontinued in patients who develop evidence of hepatic decompensation during treatment.

There are significant adverse events caused by ribavirin/peginterferon alfa-2a therapy, including severe depression and suicidal ideation, hemolytic anemia, suppression of bone marrow function, autoimmune and infectious disorders, pulmonary dysfunction, pancreatitis, and diabetes. The PEGASYS package insert and MEDICATION GUIDE should be reviewed in their entirety prior to initiation of combination treatment for additional safety information.

Treatment with RIBASPHERE (ribavirin, USP) and peginterferon alfa-2a should be administered under the guidance of a qualified physician and may lead to moderate to severe adverse experiences requiring dose reduction, temporary dose cessation or discontinuation of therapy.

Ribavirin may cause birth defects and/or death of the exposed fetus. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients. Ribavirin has demonstrated significant teratogenic and/or embryocidal effects in all animal species in which adequate studies have been conducted. These effects occurred at doses as low as one twentieth of the recommended human dose of ribavirin. RIBASPHERE (ribavirin, USP) THERAPY SHOULD NOT BE STARTED UNLESS A REPORT OF A NEGATIVE PREGNANCY TEST HAS BEEN OBTAINED IMMEDIATELY PRIOR TO PLANNED INITIATION OF THERAPY. Patients should be instructed to use at least two forms of effective contraception during treatment and for 6 months after treatment has been stopped. Pregnancy testing should occur monthly during RIBASPHERE (ribavirin, USP) therapy and for 6 months after therapy has stopped (see CONTRAINDICATIONS and PRECAUTIONS: Information for Patients and Pregnancy: Category X).

The primary toxicity of ribavirin is hemolytic anemia (hemoglobin <10 g/dL), which was observed in approximately 13% of all ribavirin and peginterferon alfa-2a treated patients in clinical trials (see PRECAUTIONS: Laboratory Tests). The anemia associated with ribavirin occurs within 1 to 2 weeks of initiation of therapy. BECAUSE THE INITIAL DROP IN HEMOGLOBIN MAY BE SIGNIFICANT, IT IS ADVISED THAT HEMOGLOBIN OR HEMATOCRIT BE OBTAINED PRETREATMENT AND AT WEEK 2 AND WEEK 4 OF THERAPY OR MORE FREQUENTLY IF CLINICALLY INDICATED. Patients should then be followed as clinically appropriate.

Fatal and nonfatal myocardial infarctions have been reported in patients with anemia caused by ribavirin. Patients should be assessed for underlying cardiac disease before initiation of ribavirin therapy. Patients with pre-existing cardiac disease should have electrocardiograms administered before treatment, and should be appropriately monitored during therapy. If there is any deterioration of cardiovascular status, therapy should be suspended or discontinued (see DOSAGE AND ADMINISTRATION: RIBASPHERE (ribavirin, USP) Dosage Modification Guidelines). Because cardiac disease may be worsened by drug induced anemia, patients with a history of significant or unstable cardiac disease should not use RIBASPHERE (ribavirin, USP) (see ADVERSE REACTIONS).

Chronic hepatitis C (CHC) patients with cirrhosis may be at risk of hepatic decompensation and death when treated with alpha interferons, including peginterferon alfa-2a. During treatment, patients’ clinical status and hepatic function should be closely monitored, and peginterferon alfa-2a treatment should be immediately discontinued if decompensation (Child-Pugh score ≥6) is observed (see CONTRAINDICATIONS).

Severe acute hypersensitivity reactions (e.g., urticaria, angioedema, bronchoconstriction, and anaphylaxis) have been rarely observed during alpha interferon and ribavirin therapy.

If such reaction occurs, therapy with peginterferon alfa-2a and ribavirin should be discontinued and appropriate medical therapy immediately instituted. Serious skin reactions including vesilculobullous eruptions, reactions in the spectrum of Stevens Johnson Syndrome (erythema multiforme major) with varying degrees of skin and mucosal involvement and exfoliative dermatitis (erythroderma) have been rarely reported in the patients receiving peginterferon alfa-2a with and without ribavirin. Patients developing signs or symptoms of severe skin reactions must discontinue therapy. (see ADVERSE REACTIONS: Postmarketing Experience).

Pulmonary symptoms, including dyspnea, pulmonary infiltrates, pneumonitis and occasional cases of fatal pneumonia, have been reported during therapy with ribavirin and interferon. In addition, sarcoidosis or the exacerbation of sarcoidosis has been reported. If there is evidence of pulmonary infiltrates or pulmonary function impairment, the patient should be closely monitored and, if appropriate, combination RIBASPHERE (ribavirin, USP)/peginterferon alfa-2a treatment should be discontinued.

RIBASPHERE (ribavirin, USP) and peginterferon alfa-2a therapy should be suspended in patients with signs and symptoms of pancreatitis, and discontinued in patients with confirmed pancreatitis.

RIBASPHERE (ribavirin, USP) should not be used in patients with creatinine clearance <50 mL/min (see CLINICAL PHARMACOLOGY: Special Populations).

RIBASPHERE (ribavirin, USP) must be discontinued immediately and appropriate medical therapy instituted if an acute hypersensitivity reaction (e.g., urticaria, angioedema, bronchoconstriction, anaphylaxis) develops. Transient rashes do not necessitate interruption of treatment.

The safety and efficacy of RIBASPHERE (ribavirin, USP) and peginterferon alfa-2a therapy for the treatment of adenovirus, RSV, parainfluenza or influenza infections have not been established. RIBASPHERE (ribavirin, USP) should not be used for these indications. Ribavirin for inhalation has a separate package insert, which should be consulted if ribavirin inhalation therapy is being considered.

The safety and efficacy of RIBASPHERE (ribavirin, USP) and peginterferon alfa-2a therapy have not been established in liver or other organ transplant patients, patients with decompensated liver disease due to hepatitis C virus infection, patients who are non-responders to interferon therapy or patients coinfected with HBV or HIV and a CD4+ cell count <100 cells/μL.

Patients must be informed that ribavirin may cause birth defects and/or death of the exposed fetus. RIBASPHERE (ribavirin, USP) therapy must not be used by women who are pregnant or by men whose female partners are pregnant. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients taking RIBASPHERE (ribavirin, USP) therapy and for 6 months posttherapy. RIBASPHERE (ribavirin, USP) therapy should not be initiated until a report of a negative pregnancy test has been obtained immediately prior to initiation of therapy. Patients must perform a pregnancy test monthly during therapy and for 6 months posttherapy.

Female patients of childbearing potential and male patients with female partners of childbearing potential must be advised of the teratogenic/embryocidal risks and must be instructed to practice effective contraception during RIBASPHERE (ribavirin, USP) therapy and for 6 months posttherapy. Patients should be advised to notify the healthcare provider immediately in the event of a pregnancy (see CONTRAINDICATIONS and WARNINGS).

The most common adverse event associated with ribavirin is anemia, which may be severe (see ADVERSE REACTIONS). Patients should be advised that laboratory evaluations are required prior to starting RIBASPHERE (ribavirin, USP) therapy and periodically thereafter (see Laboratory Tests). It is advised that patients be well hydrated, especially during the initial stages of treatment.

Patients who develop dizziness, confusion, somnolence, and fatigue should be cautioned to avoid driving or operating machinery.

Patients should be informed regarding the potential benefits and risks attendant to the use of RIBASPHERE (ribavirin, USP). Instructions on appropriate use should be given, including review of the contents of the enclosed MEDICATION GUIDE, which is not a disclosure of all or possible adverse effects.

Patients should be advised to take RIBASPHERE (ribavirin, USP) with food.

Before beginning RIBASPHERE (ribavirin, USP) therapy, standard hematological and biochemical laboratory tests must be conducted for all patients. Pregnancy screening for women of childbearing potential must be done.

After initiation of therapy, hematological tests should be performed at 2 weeks and 4 weeks and biochemical tests should be performed at 4 weeks. Additional testing should be performed periodically during therapy. Monthly pregnancy testing should be done during combination therapy and for 6 months after discontinuing therapy.

The entrance criteria used for the clinical studies of ribavirin and peginterferon alfa-2a combination therapy may be considered as a guideline to acceptable baseline values for initiation of treatment:

The maximum drop in hemoglobin usually occurred during the first 8 weeks of initiation of ribavirin therapy. Because of this initial acute drop in hemoglobin, it is advised that a complete blood count should be obtained pretreatment and at week 2 and week 4 of therapy or more frequently if clinically indicated. Additional testing should be performed periodically during therapy. Patients should then be followed as clinically appropriate.

Results from a pharmacokinetic sub-study demonstrated no pharmacokinetic interaction between peginterferon alfa-2a and ribavirin.

NRTIs

Patients receiving peginterferon alfa-2a/ribavirin and NRTIs should be closely monitored for treatment associated toxicities. Physicians should refer to prescribing information for the respective NRTIs for guidance regarding toxicity management. In addition, dose reduction or discontinuation of peginterferon alfa-2a, ribavirin or both should also be considered if worsening toxicities are observed (see WARNINGS, PRECAUTIONS, and DOSAGE AND ADMINISTRATION: Dose Modifications).

Didanosine

Co-administration of ribavirin and didanosine is not recommended. Reports of fatal hepatic failure, as well as peripheral neuropathy, pancreatitis, and symptomatic hyperlactatemia/lactic acidosis have been reported in clinical trials (see CLINICAL PHARMACOLOGY: Drug Interactions).

Zidovudine

In Study NR15961, patients who were administered zidovudine in combination with peginterferon alfa-2a/ribavirin developed severe neutropenia (ANC <500) and severe anemia (hemoglobin <8 g/dL) more frequently than similar patients not receiving zidovudine (neutropenia 15% vs. 9%) (anemia 5% vs. 1%).

Lamivudine, Stavudine, and Zidovudine

In vitro studies have shown ribavirin can reduce the phosphorylation of pyrimidine nucleoside analogs such as lamivudine, stavudine, and zidovudine.

In a p53 (+/-) mouse carcinogenicity study and a rat 2-year carcinogenicity study at doses up to the maximum tolerated doses of 100 mg/kg/day and 60 mg/kg/day, respectively, ribavirin was not oncogenic. On a body surface area basis, these doses are approximately 0.5 and 0.6 times the maximum recommended human 24-hour dose of ribavirin.

Ribavirin demonstrated mutagenic activity in the in vitro mouse lymphoma assay. No clastogenic activity was observed in an in vivo mouse micronucleus assay at doses up to 2000 mg/kg. However, results from studies published in the literature show clastogenic activity in the in vivo mouse micronucleus assay at oral doses up to 2000 mg/kg. A dominant lethal assay in rats was negative, indicating that if mutations occurred in rats they were not transmitted through male gametes. However, potential carcinogenic risk to humans cannot be excluded.

In a fertility study in rats, ribavirin showed a marginal reduction in sperm counts at the dose of 100 mg/kg/day with no effect on fertility. Upon cessation of treatment, total recovery occurred after 1 spermatogenesis cycle. Abnormalities in sperm were observed in studies in mice designed to evaluate the time course and reversibility of ribavirin-induced testicular degeneration at doses of 15 to 150 mg/kg/day (approximately 0.1 to 0.8 times the maximum recommended human 24‑hour dose of ribavirin) administered for 3 to 6 months. Upon cessation of treatment, essentially total recovery from ribavirin-induced testicular toxicity was apparent within 1 or 2 spermatogenic cycles.

Female patients of childbearing potential and male patients with female partners of childbearing potential should not receive RIBASPHERE (ribavirin, USP) unless the patient and his/her partner are using effective contraception (two reliable forms). Based on a multiple dose half-life (t) of ribavirin of 12 days, effective contraception must be utilized for 6 months posttherapy (i.e., 15 half-lives of clearance for ribavirin).

No reproductive toxicology studies have been performed using peginterferon alfa-2a in combination with RIBASPHERE (ribavirin, USP). However, peginterferon alfa-2a and ribavirin when administered separately, each has adverse effects on reproduction. It should be assumed that the effects produced by either agent alone would also be caused by the combination of the two agents.

Pregnancy: Category X (see CONTRAINDICATIONS)

Ribavirin produced significant embryocidal and/or teratogenic effects in all animal species in which adequate studies have been conducted. Malformations of the skull, palate, eye, jaw, limbs, skeleton, and gastrointestinal tract were noted. The incidence and severity of teratogenic effects increased with escalation of the drug dose. Survival of fetuses and offspring was reduced.

In conventional embryotoxicity/teratogenicity studies in rats and rabbits, observed no-effect dose levels were well below those for proposed clinical use (0.3 mg/kg/day for both the rat and rabbit; approximately 0.06 times the recommended human 24‑hour dose of ribavirin). No maternal toxicity or effects on offspring were observed in a peri/postnatal toxicity study in rats dosed orally at up to 1 mg/kg/day (approximately 0.01 times the maximum recommended human 24‑hour dose of ribavirin).

Treatment and Posttreatment: 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 is contained in sperm, and if so, 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 (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.

RIBASPHERE (ribavirin, USP) should not be used by pregnant women or by men whose female partners are pregnant. Female patients of childbearing potential and male patients with female partners of childbearing potential should not receive RIBASPHERE (ribavirin, USP) unless the patient and his/her partner are using effective contraception (two reliable forms) during therapy and for 6 months posttherapy.

Ribavirin Pregnancy Registry

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

Animal Toxicology

Long-term study in the mouse and rat (18 to 24 months; dose 20 to 75, and 10 to 40 mg/kg/day, respectively, approximately 0.1 to 0.4 times the maximum human daily dose of ribavirin) have demonstrated a relationship between chronic ribavirin exposure and an increased incidence of vascular lesions (microscopic hemorrhages) in mice. In rats, retinal degeneration occurred in controls, but the incidence was increased in ribavirin-treated rats.

It is not known whether ribavirin is excreted in human milk. Because many drugs are excreted in human milk and to avoid any potential for serious adverse reactions in nursing infants from ribavirin, a decision should be made either to discontinue nursing or therapy with RIBASPHERE (ribavirin, USP), based on the importance of the therapy to the mother.

Safety and effectiveness of RIBASPHERE (ribavirin, USP) have not been established in patients below the age of 18.

Clinical studies of ribavirin and peginterferon alfa-2a did not include sufficient numbers of subjects aged 65 or over to determine whether they respond differently from younger subjects. Specific pharmacokinetic evaluations for ribavirin in the elderly have not been performed. The risk of toxic reactions to this drug may be greater in patients with impaired renal function. RIBASPHERE (ribavirin, USP) should not be administered to patients with creatinine clearance <50 mL/min. (see CLINICAL PHARMACOLOGY: Special Populations ).

No clinically significant differences in the pharmacokinetics of ribavirin were observed between male and female subjects.

Peginterferon alfa-2a in combination with ribavirin causes a broad variety of serious adverse reactions (see BOXED WARNING and WARNINGS).

The most common life-threatening or fatal events induced or aggravated by peginterferon alfa-2a and ribavirin were depression, suicide, relapse of drug abuse/overdose, and bacterial infections, each occurring at a frequency of <1%.

In all studies, one or more serious adverse reactions occurred in 10% of CHC monoinfected patients receiving peginterferon alfa-2a alone or in combination with ribavirin. The most common serious adverse event (3% in CHC) was bacterial infection (e.g., sepsis, osteomyelitis, endocarditis, pyelonephritis, pneumonia). Other SAEs occurred at a frequency of <1% and included: suicide, suicidal ideation, psychosis, aggression, anxiety, drug abuse and drug overdose, angina, hepatic dysfunction, fatty liver, cholangitis, arrhythmia, diabetes mellitus, autoimmune phenomena (e.g., hyperthyroidism, hypothyroidism, sarcoidosis, systemic lupus erythematosus, rheumatoid arthritis), peripheral neuropathy, aplastic anemia, peptic ulcer, gastrointestinal bleeding, pancreatitis, colitis, corneal ulcer, pulmonary embolism, coma, myositis, cerebral hemorrhage, thrombotic thrombocytopenic purpura, psychotic disorder, and hallucination.

Nearly all patients in clinical trials experienced one or more adverse events. The most commonly reported adverse reactions were psychiatric reactions, including depression, insomnia, irritability, anxiety, and flu-like symptoms such as fatigue, pyrexia, myalgia, headache, and rigors. Other common reactions were anorexia, nausea and vomiting, diarrhea, arthralgias, injection site reactions, alopecia, and pruritus.

Ten percent of CHC monoinfected patients receiving 48 weeks of therapy with peginterferon alfa-2a in combination with ribavirin discontinued therapy. The most common reasons for discontinuation of therapy were psychiatric, flu-like syndrome (e.g., lethargy, fatigue, headache), dermatologic and gastrointestinal disorders and laboratory abnormalities (thrombocytopenia, neutropenia, and anemia).

Overall 39% of patients with CHC required modification of peginterferon alfa-2a and/or ribavirin therapy. The most common reason for dose modification of peginterferon alfa-2a in CHC patients was for laboratory abnormalities; neutropenia (20%) and thrombocytopenia (4%). The most common reason for dose modification of ribavirin in CHC patients was anemia (22%).

Peginterferon alfa-2a dose was reduced in 12% of patients receiving 1000 mg to 1200 mg ribavirin for 48 weeks and in 7% of patients receiving 800 mg ribavirin for 24 weeks. Ribavirin dose was reduced in 21% of patients receiving 1000 mg to1200 mg ribavirin for 48 weeks and in 12% of patients receiving 800 mg ribavirin for 24 weeks.

Chronic hepatitis C monoinfected patients treated for 24 weeks with peginterferon alfa-2a and 800 mg ribavirin were observed to have lower incidence of serious adverse events (3% vs. 10%), hemoglobin <10 g/dL (3% vs. 15%), dose modifications of peginterferon alfa-2a (30% vs. 36%) and ribavirin (19% vs. 38%), and of withdrawal from treatment (5% vs. 15%) compared to patients treated for 48 weeks with peginterferon alfa-2a and 1000 mg or 1200 mg ribavirin. On the other hand, the overall incidence of adverse events appeared to be similar in the two treatment groups.

Because clinical trials are conducted under widely varying and controlled conditions, adverse reaction rates observed in clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug. Also, the adverse event rates listed here may not predict the rates observed in a broader patient population in clinical practice.

Table 3 Adverse Reactions Occurring in ≥5% of Patients in Chronic Hepatitis C Clinical Trials (Study NV15801*)
Body System CHC Combination Therapy Study NV15801
Peginterferon alfa‑2a 180 µg + 1000 mg or 1200 mg Ribavirin 48 week Interferon alfa-2b + 1000 mg or 1200 mg  Ribavirin 48 week
  N=451 N=443
  % %
* Described as Study 4 in the PEGASYS Package Insert. ** Severe hematologic abnormalities (lymphocyte <0.5 x 109/L; hemoglobin <10 g/dL; neutrophil <0.75 x 109/L; platelet <50 x 109/L).
Application Site Disorders    
Injection site reaction 23 16
Endocrine Disorders    
Hypothyroidism 4 5
Flu‑like Symptoms and Signs    
Fatigue/Asthenia 65 68
Pyrexia 41 55
Rigors 25 37
Pain 10 9
Gastrointestinal    
Nausea/Vomiting 25 29
Diarrhea 11 10
Abdominal pain 8 9
Dry mouth 4 7
Dyspepsia 6 5
Hematologic**    
Lymphopenia 14 12
Anemia 11 11
Neutropenia 27 8
Thrombocytopenia 5 <1
Metabolic and Nutritional    
Anorexia 24 26
Weight decrease 10 10
Musculoskeletal, Connective Tissue and Bone    
Myalgia 40 49
Arthralgia 22 23
Back pain 5 5
Neurological    
Headache 43 49
Dizziness (excluding vertigo) 14 14
Memory impairment 6 5
Psychiatric    
Irritability/Anxiety/Nervousness 33 38
Insomnia 30 37
Depression 20 28
Concentration impairment 10 13
Mood alteration 5 6
Resistance Mechanism Disorders    
Overall 12 10
Respiratory, Thoracic and Mediastinal    
Dyspnea 13 14
Cough 10 7
Dyspnea exertional 4 7
Skin and Subcutaneous Tissue    
Alopecia 28 33
Pruritus 19 18
Dermatitis 16 13
Dry skin 10 13
Rash 8 5
Sweating increased 6 5
Eczema 5 4
Visual Disorders    
Vision blurred 5 2

Anemia due to hemolysis is the most significant toxicity of ribavirin therapy. Anemia (hemoglobin <10 g/dL) was observed in 13% of all ribavirin and peginterferon alfa-2a combination-treated patients in clinical trials. The maximum drop in hemoglobin occurred during the first 8 weeks of initiation of ribavirin therapy (see DOSAGE AND ADMINISTRATION: Dose Modifications).

The following adverse reactions have been identified and reported during post-approval use of peginterferon alfa-2a therapy: hearing impairment, hearing loss, serious skin reactions, and dehydration (see WARNINGS: Hypersensitivity).

No cases of overdose with ribavirin have been reported in clinical trials. Hypocalcemia and hypomagnesemia have been observed in persons administered greater than the recommended dosage of ribavirin. In most of these cases, ribavirin was administered intravenously at dosages up to and in some cases exceeding four times the recommended maximum oral daily dose.

The recommended dose of RIBASPHERE (ribavirin, USP) tablets is provided in Table 4. The recommended duration of treatment for patients previously untreated with ribavirin and interferon is 24 to 48 weeks.

The daily dose of RIBASPHERE (ribavirin, USP) is 800 mg to 1200 mg administered orally in two divided doses. The dose should be individualized to the patient depending on baseline disease characteristics (e.g., genotype), response to therapy, and tolerability of the reg

Manufacturer

PAR Pharmaceutical Companies, Inc.

Active Ingredients

Source

Drugs and Medications [2 Associated Drugs and Medications listed on BioPortfolio]

Ribasphere ribapak [Three Rivers Pharmaceuticals, LLC]

These highlights do not include all the information needed to use Ribasphere (ribavirin, USP) safely and effectively. See full prescribing information for Ribasphere (ribavirin, USP). Ribasphere (riba...

Ribasphere [Three Rivers Pharmaceuticals, LLC]

These highlights do not include all the information needed to use Ribasphere (ribavirin capsules) safely and effectively. See full prescribing information for Ribasphere.Ribasphere (Ribavirin Capsules...

Clinical Trials [2 Associated Clinical Trials listed on BioPortfolio]

Drug Interaction Study With Ribavirin and Abacavir in Male Subjects With Hepatitis C Who Have Failed Ribavirin Treatment

This research is being done to find out whether abacavir (Ziagen®) lowers the levels of ribavirin (Ribapak®) in the body of persons taking these two drugs.

Efficacy and Safety Study of Pegylated Interferon Lambda-1a With Ribavirin and Daclatasvir, to Treat naïve Subjects With Chronic HCV Genotypes 1, 2, 3, and 4 Who Are Co-infected With HIV

To evaluate Sustained Virologic Response at post treatment Week 12 (SVR12)following treatment with Lambda/RBV/DCV in chronic HCV GT-1, -2, -3 or -4 subjects co-infected with HIV-1

PubMed Articles [0 Results]

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