Interferon Alfa-2B / Ribavirin Dosage

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Chronic Hepatitis C

75 kg or less: Ribavirin 400 mg orally in the morning and 600 mg in the evening plus interferon alfa-2b 3 million international units subcutaneously 3 times a week

Greater than 75 kg: Ribavirin 600 mg orally twice a day plus interferon alfa-2b 3 million international units subcutaneously 3 times a week

Duration:
For patients previously untreated with interferon: 24 to 48 weeks
For patients who relapse following interferon treatment: 24 weeks

Usual Adult Dose for Cryoglobulinemia

Study (n=9)
HCV related Mixed Cryoglobulinemia: Interferon alfa-2b 3 million international units subcutaneously 3 times a week plus ribavirin 15 mg/kg orally daily for 6 months

Usual Pediatric Dose for Chronic Hepatitis C

3 years or older:
25 to 36 kg: Ribavirin 200 mg orally twice a day plus interferon alfa-2b 3 million international units/m2 3 times a week

37 to 49 kg: Ribavirin 200 mg orally in the morning and 400 mg in the evening plus interferon alfa-2b 3 million international units/m2 3 times a week

50 to 61 kg: Ribavirin 400 mg orally twice a day plus interferon alfa-2b 3 million international units/m2 3 times a week

Greater than 61 kg: Use adult dosage

Renal Dose Adjustments

CrCl less than 50 mL/min: Not recommended.

Liver Dose Adjustments

Data not available

Dose Adjustments

If severe adverse reactions or laboratory abnormalities develop during combination treatment, dosage modification or discontinuation until the adverse reaction abates or decreases in severity is recommended. Combination therapy should be discontinued if intolerance persists after dose adjustment.

Treatment discontinuation should be considered in any patient receiving interferon alfa-2b-ribavirin whose HCV-RNA levels remain detectable after 24 weeks of therapy.

Interferon alfa-2b should temporarily be reduced and/or medical therapy should be considered in patients experiencing moderate depression (persistent low mood, loss of interest, poor self image, and/or hopelessness). Patients with severe depression or suicidal ideation/attempt should discontinue interferon alfa-2b-ribavirin therapy and should be followed closely with appropriate medical management.

Adults:
Hemoglobin (Hgb) less than 10 g/dL: Ribavirin should be reduced to 600 mg per day (200 mg in the morning and 400 mg in the evening).

In patients with history of stable cardiovascular disease:
Hgb 2 g/dL or greater decrease during any 4-week interval: Permanently reduce to ribavirin 600 mg orally per day (200 mg in the morning and 400 mg in the evening) plus interferon alfa-2b 1.5 million international units subcutaneously 3 times per week.

Hgb less than 12 g/dL following 4 weeks of reduced dosage: Interferon alfa-2b-ribavirin should be permanently discontinued.

Interferon alfa-2b should be reduced to 1.5 million international units subcutaneously 3 times per week if any of the following occurs:
White blood count less than 1.5 x 10(9)/L
Neutrophil count less than 0.75 x 10(9)/L
Platelet count less than 50 x 10(9)/L

Interferon alfa-2b-ribavirin should be permanently discontinued if any of the following occurs:
Hgb less than 8.5 g/dL
White blood count less than 1 x 10(9)/L
Neutrophil count less than 0.5 x 10(9)/L
Platelet count less than 25 x 10(9)/L

Pediatrics:
Hgb less than 10 g/dL: Ribavirin should be reduced to half the usual dosage.

In patients with history of stable cardiovascular disease:
Hgb 2 g/dL or greater decrease during any 4-week interval: Permanently reduce to half the usual dosage of ribavirin plus interferon alfa-2b 1.5 million international units/m2 subcutaneously 3 times per week.

Hgb less than 12 g/dL following 4 weeks of reduced dosage: Permanently discontinue interferon alfa-2b-ribavirin.

Interferon alfa-2b should be reduced to 1.5 million international units/m2 subcutaneously 3 times per week if any of the following occurs:
White blood count less than 1.5 x 10(9)/L
Neutrophil count less than 0.75 x 10(9)/L
Platelet count less than 80 x 10(9)/L

Interferon alfa-2b-ribavirin should be permanently discontinued if any of the following occurs:
Hgb less than 8.5 g/dL
White blood count less than 1 x 10(9)/L
Neutrophil count less than 0.5 x 10(9)/L
Platelet count less than 50 x 10(9)/L

Precautions

Interferon alfa-2b-ribavirin therapy is contraindicated in women who are pregnant and in the male partners of women who are pregnant. A negative pregnancy test should be obtained immediately prior to initiation of combination therapy. Extreme care must be taken to avoid pregnancy during therapy and for 6 months after completion of therapy in female patients, and in female partners of male patients who are taking interferon alfa-2b-ribavirin. Women of childbearing potential and men must use two reliable forms of effective contraception during treatment and during the 6-month posttreatment follow-up period. If pregnancy occurs in a patient or partner of a patient during treatment or during the 6 months after treatment cessation, physicians are encouraged to report such cases by calling 1-800-727-7064 (USA).

Alpha interferons, including interferon alfa-2b, cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Patients should be monitored closely with periodic clinical and laboratory evaluations. Patients with persistently severe or worsening signs or symptoms of these conditions should be withdrawn from therapy. In many but not all cases these disorders resolve after stopping interferon alfa-2b therapy.

Interferon alfa-2b-ribavirin therapy is contraindicated in patients with autoimmune hepatitis, patients with hemoglobinopathies (e.g., thalassemia and sickle cell anemia), and patients with creatinine clearance less than 50 mL/min.

Hemolytic anemia (hemoglobin less than 10 g/dL) was observed in approximately 10% of patients treated with interferon alfa-2b-ribavirin in clinical trials. Anemia occurred within 1 to 2 weeks of initiation of ribavirin therapy. Complete blood counts should be obtained pretreatment, at Week 2 and Week 4 of therapy or more frequently if clinically indicated. Patients should then be monitored as clinically appropriate.

Deterioration of cardiac function and/or exacerbation of the symptoms of coronary disease may occur due to the anemia associated with interferon alfa-2b-ribavirin therapy. Fatal and nonfatal myocardial infarctions have been reported in patients with anemia caused by ribavirin. Patients should be assessed before initiation of therapy and monitored during therapy. Patients with a history of significant or unstable cardiac disease should not use interferon alfa-2b-ribavirin. Therapy should be suspended or discontinued if cardiovascular status deteriorates.

Severe psychiatric side effects, including depression, psychoses, aggressive behavior, hallucinations, violent behavior (suicidal ideation, suicide attempts, suicides), and rare cases of homicidal ideation have been reported during interferon alfa-2b-ribavirin therapy in patients with and without a previous psychiatric disorder. Extreme caution is recommended if interferon alfa-2b-ribavirin is used in patients with a history of psychiatric disorder. All patients should be carefully monitored for depression and other psychiatric symptoms. Suspension of therapy should be considered if psychiatric symptoms are not controlled by psychiatric intervention and/or dose reduction. In severe cases, interferon alfa-2b-ribavirin should be stopped at once and psychiatric intervention should be sought.

Interferon alfa-2b treatment suppresses bone marrow function and may result in severe cytopenias including aplastic anemia. It is recommended that complete blood counts be obtained pretreatment and monitored routinely during therapy. Interferon alfa-2b treatment should be discontinued in patients who develop severe decreases in neutrophil (less than 0.5 x 10(9)/L) or platelet counts (less than 25 x 10(9)/L).

Standard hematologic tests (including hemoglobin, complete and differential white blood cell counts, and platelet count) and blood chemistries (electrolytes, liver function tests, and TSH) are recommended prior to initiating therapy and periodically thereafter.

Pulmonary symptoms (including dyspnea, pulmonary infiltrates, pneumonitis, pulmonary hypertension, pneumonia, and fatal pneumonia), sarcoidosis, and exacerbation of sarcoidosis have been reported. Patients should be closely monitored if there is evidence of pulmonary infiltrates or pulmonary function impairment. Treatment should be stopped if appropriate.

Pancreatitis (fatal and nonfatal) has been reported with interferon alfa-2b-ribavirin. Interferon alfa-2b-ribavirin therapy should be suspended in patients with signs and symptoms of pancreatitis, and discontinued in patients with confirmed pancreatitis.

Elevated triglyceride levels have been reported with interferon alfa-2b-ribavirin therapy. Elevated triglyceride levels should be managed as clinically appropriate. Severe hypertriglyceridemia (triglycerides greater than 1000 mg/dL) may result in pancreatitis. Discontinuation of interferon alfa-2b-ribavirin therapy should be considered for patients with persistently elevated triglycerides (triglycerides greater than 1000 mg/dL) associated with symptoms of potential pancreatitis, such as abdominal pain, nausea, or vomiting.

Acute serious hypersensitivity reactions (e.g., urticaria, angioedema, bronchoconstriction, and anaphylaxis) have been reported in patients treated with interferon alfa-2b. Therapy should be discontinued immediately and appropriate medical therapy instituted if such a reaction develops with interferon alfa-2b-ribavirin therapy. Transient rashes have been observed in some patients following injection, but have not necessitated treatment interruption.

Exacerbation of autoimmune disease has been reported in patients receiving alpha interferon therapy, including interferon alfa-2b. Interferon alfa-2b-ribavirin should be used with caution in patients with other autoimmune disorders.

Decrease or loss of vision, retinopathy including macular edema, retinal artery or vein thrombosis, retinal hemorrhages and cotton wool spots, optic neuritis, papilledema, and serous retinal detachment may be induced or aggravated by alpha interferon therapy. All patients should have an eye examination at baseline. Patients with preexisting ophthalmologic disorders (e.g., diabetic or hypertensive retinopathy) should receive periodic ophthalmic exams during interferon alpha therapy. Any patient developing ocular symptoms should get a complete eye examination at once. Interferon alfa-2b-ribavirin therapy should be discontinued in patients who develop new or worsening ophthalmologic disorders.

Infrequently, patients receiving interferon alfa-2b treatment developed thyroid abnormalities, either hypothyroid or hyperthyroid. The mechanism by which interferon alfa-2b may alter thyroid function is not known. Use of interferon alfa-2b-ribavirin is not recommended in patients with preexisting thyroid abnormalities whose thyroid function cannot be maintained within the normal range by medication. Before treatment, patient's TSH should be evaluated. Patients developing symptoms consistent with possible thyroid dysfunction during therapy should have their thyroid function evaluated and appropriate therapy instituted. Interferon alfa-2b-ribavirin should be discontinued for patients developing thyroid abnormalities during therapy whose thyroid function cannot be controlled by medication. Discontinuation of interferon alfa-2b has not always reversed thyroid dysfunction which occurred during therapy with interferon alfa-2b.

Episodes of hyperglycemia, new onset diabetes mellitus, and exacerbation of preexisting diabetes mellitus have been reported in patients treated with interferon alfa-2b. Interferon alfa-2b therapy should not be started in patients with preexisting diabetes mellitus who cannot be effectively treated by medication. Patients who develop such conditions during treatment and cannot be controlled with medication should not continue interferon alfa-2b therapy.

Exacerbation of preexisting psoriasis and sarcoidosis, as well as development of new sarcoidosis, has been reported. Interferon alfa-2b-ribavirin therapy should only be used in such patients if the potential benefit justifies the potential risk.

The safety and efficacy of interferon alfa-2b-ribavirin has not been established in patients with liver or other organ transplants, decompensated hepatitis C, coinfection with HBV or HIV, or who are nonresponders to interferon therapy.

Ribavirin monotherapy is not effective for the treatment of chronic hepatitis C and should not be used alone for this indication. The safety and efficacy of ribavirin monotherapy has not been established for the treatment of HIV infection, adenovirus, early RSV infection, parainfluenza, or influenza. Ribavirin should not be used for these indications.

Safety and efficacy have not been established in adults beyond 48 weeks in previously untreated patients and beyond 24 weeks in relapse patients. Safety and efficacy have not been established beyond 48 weeks in pediatric patients.

Safety and efficacy of ribavirin capsules have not been established in pediatric patients less than 3 years of age.

Dialysis

Ribavirin is not removed by hemodialysis.

Other Comments

Ribavirin should be taken with food. Ribavirin capsules should not be opened, crushed, or broken under any circumstances.

Patients should be well hydrated, especially during the initial stages of therapy.

Virologic response should be reviewed after 24 weeks of therapy.

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