Interferon Alfa-2B Dosage

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Usual Adult Dose for Hairy Cell Leukemia

2 million international units/m2 IM or subcutaneously 3 times a week for up to 6 months; higher doses are not recommended

Interferon alfa-2b should be administered subcutaneously (and not IM) in patients with platelet counts below 50,000/mm3.

Responding patients may benefit from continued treatment. A minimum effective dose has not yet been established.

Usual Adult Dose for Malignant Melanoma

Induction phase: 20 million international units/m2 by IV infusion (over 20 minutes) for 5 consecutive days per week for 4 weeks

Maintenance phase: 10 million international units/m2 subcutaneously 3 times per week for 48 weeks

Usual Adult Dose for Follicular Lymphoma

5 million international units subcutaneously 3 times a week for up to 18 months in conjunction with anthracycline-containing chemotherapy regimen and following completion of the chemotherapy regimen

Doses of myelosuppressive drugs were reduced by 25% from a full-dose CHOP regimen, and cycle length increased by 33% (e.g., from 21 to 28 days) when alpha interferon was added to the regimen.

Usual Adult Dose for Condylomata Acuminata

1 million international units injected into each lesion (maximum of 5 lesions in a single course) 3 times per week on alternate days for 3 weeks; an additional course may be administered at 12 to 16 weeks

The injection should be administered intralesionally using a tuberculin or similar syringe and a 25- to 30-gauge needle. The needle should be directed at the center of the base of the wart and at an angle almost parallel to the plane of the skin (approximately that in the commonly used PPD test). This will deliver the interferon to the dermal core of the lesion, infiltrating the lesion and causing a small wheal. Care should be taken not to go beneath the lesion too deeply; subcutaneous injection should be avoided, since this area is below the base of the lesion. Do not inject too superficially since this will result in possible leakage, infiltrating only the keratinized layer and not the dermal core.

Usual Adult Dose for Kaposi's Sarcoma

AIDS-related Kaposi's sarcoma: 30 million international units/m2 subcutaneously or IM 3 times a week until disease progression or maximal response has been achieved after 16 weeks of therapy

Dose reduction is often required.

Usual Adult Dose for Chronic Hepatitis C

3 million international units subcutaneously or IM 3 times a week

In patients tolerating therapy with normalization of ALT at 16 weeks of treatment, therapy should be extended to 18 to 24 months (72 to 96 weeks) at 3 million international units 3 times a week to improve the sustained response rate. Patients who do not normalize their ALTs or have persistently high levels of HCV RNA after 16 weeks of therapy rarely achieve a sustained response with extension of treatment. Consideration should be given to discontinuing these patients from therapy.

Usual Adult Dose for Chronic Hepatitis B

30 million to 35 million international units per week subcutaneously or IM, either as 5 million international units once a day or as 10 million international units 3 times a week for 16 weeks

Usual Adult Dose for Conjunctival Mucosa-Associated Lymphoid Tissue Lymphoma

(Not approved by FDA)

Case Report - Conjunctival MALT Lymphoma
1 million international units intralesional injection 3 times a week for a total of 12 doses

Usual Pediatric Dose for Chronic Hepatitis C

3 years or older: 3 million international units subcutaneously or IM 3 times a week in combination with ribavirin (capsules or oral solution)

In patients tolerating therapy with normalization of ALT at 16 weeks of treatment, therapy should be extended to 18 to 24 months (72 to 96 weeks) at 3 million international units 3 times a week to improve the sustained response rate. Patients who do not normalize their ALTs or have persistently high levels of HCV RNA after 16 weeks of therapy rarely achieve a sustained response with extension of treatment. Consideration should be given to discontinuing these patients from therapy.

Usual Pediatric Dose for Chronic Hepatitis B

1 year or older: 3 million international units/m2 subcutaneously 3 times a week for the first week of therapy followed by dose escalation to 6 million international units/m2 3 times a week (maximum of 10 million international units 3 times a week) for a total duration of 16 to 24 weeks

Usual Pediatric Dose for Angioblastoma

(Not approved by FDA)

Case Reports - Giant Cell Angioblastoma
Greater than 4 months: 3 million international units/m2 subcutaneously daily

Usual Pediatric Dose for Idiopathic (Immune) Thrombocytopenic Purpura

(Not approved by FDA)

Study (n=14)
Greater than 4 years old: 3 million international units/m2 subcutaneously 3 times a week for 4 weeks

In patients with no increase or partial increase in platelets (less than 150 x 10(9)/L) continue therapy for another 8 weeks.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

HAIRY CELL LEUKEMIA:
If severe adverse reactions develop: Dose should be modified (50% reduction) or therapy should be temporarily discontinued until the adverse reactions abate and then resumed at 50% (1 million international units/m2 3 times a week).

If severe adverse reactions persist or recur after dose adjustment: Interferon alfa-2b should be permanently discontinued.

Progressive disease or failure to respond after 6 months of therapy: Interferon alfa-2b should be discontinued.

MALIGNANT MELANOMA:
Regular laboratory testing should be performed to monitor laboratory abnormalities for the purposes of dose modification.

Severe adverse reactions, including granulocyte counts greater than 250/mm3 but less than 500/mm3 or SGPT/SGOT greater than 5 to 10 times the upper limit of normal (ULN): Interferon alfa-2b should be withheld until adverse reactions subside. Treatment should be restarted at 50% of the previous dose.

Granulocyte count less than 250/mm3 or SGPT/SGOT greater than 10 times the ULN, toxicity that does not abate after withholding therapy, and/or severe adverse reactions that recur in patients receiving reduced doses: Interferon alfa-2b should be permanently discontinued.

FOLLICULAR LYMPHOMA:
Neutrophil count less than 1500/mm3 or platelet count less than 75,000/mm3: Chemotherapy cycle should be delayed.

SGOT exceeds greater than 5 times ULN or serum creatinine greater than 2 mg/dL: Interferon alfa-2b should be permanently discontinued.

Neutrophil count less than 1000/mm3 or platelet count less than 50,000/mm3: Interferon alfa-2b therapy should be withheld.

Neutrophil count greater than 1000/mm3 but less than 1500/mm3: Dose should be reduced by 50% (2.5 million international units 3 times a week). The dose may be re-escalated to the initial dose (5 million international units 3 times a week) after resolution of hematologic toxicity (absolute neutrophil count greater than 1500/mm3).

AIDS-RELATED KAPOSI'S SARCOMA:
Severe adverse reactions: Dose should be reduced by 50% or withheld.

If severe adverse reactions abate with therapy interruption: Interferon alfa-2b may be resumed at a reduced dose.

If severe adverse reactions persist or recur after dose reduction: Interferon alfa-2b should be permanently discontinued.

CHRONIC HEPATITIS C:
If severe adverse reactions develop during therapy: Dose should be modified (50% reduction) or therapy should be temporarily discontinued until the adverse reactions subside.

If intolerance persists after dose adjustment: Interferon alfa-2b should be discontinued.

CHRONIC HEPATITIS B:
If severe adverse reactions or laboratory abnormalities develop during therapy: Dose should be modified (50% reduction) or discontinued if appropriate, until the adverse reactions subside.

If intolerance persists after dose adjustment: Interferon alfa-2b should be discontinued.

For patients with decreases in white blood cell, granulocyte, or platelet counts:
White blood cell count less than 1.5 x 10(9)/L, granulocyte count less than 0.75 x 10(9)/L, and/or platelet count less than 50 x 10(9)/L: Dose should be reduced 50%. Therapy was resumed at up to 100% of the initial dose when white blood cell, granulocyte, and/or platelet counts returned to normal or baseline values.

White blood cell count less than 1 x 10(9)/L, granulocyte count less than 0.5 x 10(9)/L, and/or platelet count less than 25 x 10(9)/L: Interferon alfa-2b should be permanently discontinued.

Precautions

Interferon alfa-2b causes or aggravates 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 therapy.

Interferon alfa-2b is contraindicated in patients with decompensated liver disease and patients with autoimmune hepatitis. Interferon alfa-2b plus ribavirin combination therapy is contraindicated in women who are pregnant, men whose female partners are pregnant, patients with hemoglobinopathies (e.g., thalassemia major, sickle cell anemia), and patients with CrCl less than 50 mL/min.

Ribavirin may cause birth defects and/or death of the unborn infant. Extreme care must be observed to avoid pregnancy in female patients and in female partners of male patients. Ribavirin should not be initiated until a negative pregnancy test has been obtained immediately prior to the planned start of therapy. Patients should use at least 2 effective forms of birth control simultaneously and a pregnancy test should be repeated every month.

Patients with a history of autoimmune disease and patients who are immunosuppressed transplant recipients should not be treated with interferon alfa-2b. Worsening liver disease, including jaundice, hepatic encephalopathy, hepatic failure, and death after interferon alfa-2b therapy have been reported in such patients. Any patient developing signs and symptoms of liver failure should discontinue therapy.

Hepatotoxicity (including fatality) has been reported. Any patient developing liver function abnormalities during treatment should be monitored closely. If needed, treatment should be discontinued.

Chronic hepatitis B patients should be monitored closely if increases in ALT occur during treatment for chronic hepatitis B. Monitoring of clinical symptomatology and liver function tests including ALT, prothrombin time, alkaline phosphatase, albumin, and bilirubin is recommended. The potential risks must be weighed against the potential benefits when considering interferon alfa-2b for these patients.

Interferon alfa-2b should not be used in patients with AIDS-related Kaposi's sarcoma with rapidly progressive visceral disease.

Fever and other influenza-like symptoms have been reported with the use of interferon alfa-2b. Therefore, caution is recommended if this medication is to be used in patients with debilitating medical conditions such as a history of pulmonary disease (including chronic obstructive pulmonary disease), diabetes mellitus prone to ketoacidosis, severe myelosuppression, and/or coagulation disorders including thrombophlebitis and pulmonary embolism.

Caution is recommended if use of interferon alfa-2b is needed in patients with a history of cardiovascular disease, including patients with a history of myocardial infarction and/or previous or current arrhythmic disorder. Close monitoring is recommended in these patients. Cardiovascular adverse events, which include hypotension, arrhythmia, or tachycardia of 150 beats per minute or greater, and rarely, cardiomyopathy and myocardial infarction, have been observed in some patients administered interferon alfa-2b therapy. Some patients with these adverse experiences had no history of cardiovascular disease. Transient cardiomyopathy was observed in patients with AIDS-related Kaposi's sarcoma. Hypotension may occur during interferon alfa-2b administration, or up to 2 days posttherapy, and require supportive treatment including fluid replacement to maintain intravascular volume. Supraventricular arrhythmias occurred rarely and appeared to be correlated with preexisting conditions and prior treatment with cardiotoxic agents. These adverse events were controlled by modifying the dose or discontinuing therapy, but may require specific additional therapy. Patients with preexisting cardiac abnormalities and/or cancer (advanced stages) should have electrocardiograms taken prior to and during therapy.

Depression and suicidal behavior including suicidal ideation, suicide attempts and completed suicides, homicidal ideation, and aggressive behavior sometimes directed towards others, have been reported in patients receiving interferon alfa-2b. If patients develop psychiatric problems, including clinical depression, it is advised that the patients be carefully monitored during therapy and in the 6-month follow-up period. Interferon alfa-2b should be used with caution in patients with a history of psychiatric disorders. Any patient developing severe psychiatric disorder during therapy should discontinue interferon alfa-2b. Obtundation and coma have been reported primarily in the elderly at higher doses. These effects are generally rapidly reversible upon discontinuation of interferon alfa-2b; however, full resolution has taken up to three weeks in some severe episodes. If psychiatric problems persist or worsen, or suicidal ideation or aggressive behavior towards others is identified, it is recommended that treatment with interferon alfa-2b be discontinued and the patient followed, with psychiatric intervention as necessary. Narcotics, hypnotics, or sedatives may be used with caution. Patients should be monitored closely until adverse effects have resolved. Cases of encephalopathy have also been reported in some patients, usually elderly, treated with higher doses of interferon alfa-2b. If interferon treatment is started in patients with history or existence of psychiatric condition or with history of substance use disorders, drug screening and periodic health evaluation (including psychiatric symptom monitoring) should be considered. Early intervention for recurrence or development of neuropsychiatric symptoms and substance use is recommended.

When interferon alfa-2b is given in combination with ribavirin, patients with impaired renal function and/or those over 50 years of age should be carefully monitored for the development of anemia.

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. Differential white blood cell count and liver function tests should be monitored weekly during the induction phase and monthly during the maintenance phase of malignant melanoma therapy. Since mild-to-moderate leukopenia and elevated serum liver enzyme (SGOT) levels have been reported with intralesional administration, monitoring of these laboratory parameters should be considered.

Decrease or loss of vision, retinopathy including macular edema, retinal artery or vein thrombosis, retinal hemorrhages and cotton wool spots, optic neuritis, serous retinal detachment, and papilledema may be induced or aggravated by therapy with interferon alfa-2b or other alpha interferons. All patients should be given an eye examination at baseline. Patients with preexisting ophthalmologic disorders (e.g., diabetic or hypertensive retinopathy) should receive periodic ophthalmologic exams during interferon alpha therapy. Any patient developing ocular symptoms should have a complete eye examination at once. Interferon alfa-2b 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 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. Discontinuation of interferon alfa-2b has not always reversed thyroid dysfunction which occurred during therapy with interferon alfa-2b. Diabetes mellitus has been reported in patients treated with alpha interferons. Patients with these conditions who cannot be effectively treated by medications should not begin interferon alfa-2b treatment. Patients who develop these conditions during treatment and cannot be controlled with medication should not continue interferon alfa-2b treatment.

Dyspnea, pulmonary infiltrates, interstitial pneumonitis, pneumonia, bronchiolitis obliterans, pulmonary hypertension, and sarcoidosis (sometimes fatal or resulting in respiratory failure) may be induced or aggravated by alpha interferons, including interferon alfa-2b. Respiratory failure has recurred with interferon rechallenge. Any patient developing fever, cough, dyspnea, or other respiratory symptoms should have a chest X-ray taken. If the X-ray shows pulmonary infiltrates or evidence of pulmonary function impairment, the patient should be monitored closely. If needed, treatment should be discontinued. These adverse events have been reported in patients with hepatitis C (most often) and oncologic disease. Baseline chest X-rays are recommended and should be repeated if clinically indicated.

Rare cases of autoimmune diseases including thrombocytopenia, vasculitis, Raynaud's phenomenon, rheumatoid arthritis, lupus erythematosus, and rhabdomyolysis have been reported in patients treated with alpha interferons, including interferon alfa-2b. In very rare cases, the event resulted in fatality. The mechanism by which these events developed and their relationship to interferon alpha therapy has not been determined. Any patient developing an autoimmune disorder during treatment should be monitored closely. If needed, treatment should be discontinued.

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

Variations in dosage, route of administration, and adverse reactions exist among different brands of interferon. Therefore, it is not advised to use different brands of interferon in any single treatment regimen.

Elevated triglyceride levels have been reported with interferon alfa-2b therapy. Elevated triglyceride levels should be managed as clinically appropriate. Hypertriglyceridemia may result in pancreatitis. Discontinuation of interferon alfa-2b 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.

Exacerbation of preexisting psoriasis and sarcoidosis, as well as development of new sarcoidosis, has been reported in patients receiving interferon alfa-2b. Therefore, interferon alfa-2b therapy is only recommended for use in such patients if the potential benefit justifies the potential risk.

Safety and efficacy for the treatment of chronic hepatitis B have not been established in pediatric patients less than 1 year of age. Safety and efficacy of interferon alfa-2b in combination with ribavirin for the treatment of chronic hepatitis C have not been established in pediatric patients less than 3 years of age. Safety and efficacy of interferon alfa-2b monotherapy for the treatment of chronic hepatitis C have not been established in pediatric patients (less than 18 years of age). Safety and efficacy for the treatment of hairy cell leukemia, malignant melanoma, follicular Non-Hodgkin's lymphoma, condylomata acuminata, and AIDS-related Kaposi's sarcoma have not been established in pediatric patients (less than 18 years of age).

Dialysis

Data not available

Other Comments

At the discretion of the physician, the patient may self-administer the medication.

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

To enhance tolerability, injections should be administered in the evening, when possible. Additionally, acetaminophen may be administered at the time of injection to reduce the incidence of certain side effects. Before using, the solution should be allowed to come to room temperature.

Not all dosage forms and strengths are appropriate for some indications. Intron(R) A Solution for Injection is not recommended for IV administration and should not be used for the induction phase of malignant melanoma. The 18 million or 50 million international units/vial of Intron(R) A Powder for Injection, the 18 million international units multidose vial of Intron(R) A Solution for Injection, and the multidose pens should not be used for condylomata acuminata. Intron(R) A Solution for Injection should not be used for AIDS-related Kaposi's sarcoma since the concentrations are inappropriate.

The powder formulations of this agent contain albumin, a derivative of human blood. Based on effective donor screening and product manufacturing processes, it carries an extremely low risk for transmission of viral diseases. A theoretical risk for transmission of Creutzfeldt-Jakob disease (CJD) is also considered extremely low. No cases of transmission of viral disease or CJD have ever been reported for albumin.

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