|Interferons are a family of proteins, produced by nucleated cells, that have anti-viral, anti-proliferative, and immune-regulating activity. There are 16 known subtypes of alpha interferons. Interferons interact with cells through high affinity cell surface receptors. Multiple effects have been detected: inhibition of cellular growth, alteration in surface antigen expression, increased phagocytic activity of macrophages, augmentation of cytotoxicity of lymphocytes for target cells.|
| CLINICAL PHARMACOLOGY
The mechanism by which Interferon alfa-2a, recombinant, or any other interferon, exerts antitumor or antiviral activity is not clearly understood. However, it is believed that direct antiproliferative action against tumor cells, inhibition of virus replication and modulation of the host immune response play important roles in antitumor and antiviral activity.
INDICATIONS AND USAGE
For Patients With Chronic Hepatitis C
Chronic myelogenous leukemia (CML): SubQ, I.M.: 9 million units/day, continue treatment until disease progression
AIDS-related Kaposi's sarcoma: SubQ, I.M.: 36 million units/day for 10-12 weeks, then 36 million units 3 times/week; to minimize adverse reactions, can use escalating dose (3-, 9-, then 18 million units each day for 3 days, then 36 million units daily thereafter).
Hepatitis C: SubQ, I.M.: 3 million units 3 times/week for 12 months
Baseline ophthalmologic exam should be performed in all patients, with periodic reassessment in patients with impairment. Patients with thyroid dysfunction should be monitored by TSH levels at baseline and every 3 months during therapy.
CML/hairy cell leukemia: Hematologic monitoring should be performed monthly.
The interferons are a family of naturally occurring small proteins and glycoproteins with molecular weights of approximately 15,000 to 27,600 daltons produced and secreted by cells in response to viral infections and to synthetic or biological inducers.
Lymphoma (follicular): SubQ: 5 million units 3 times/week for up to 18 months
Malignant melanoma: 20 million units/m 2 I.V. for 5 consecutive days per week for 4 weeks, then 10 million units/m 2 SubQ 3 times/week for 48 weeks
AIDS-related Kaposi's sarcoma: I.M., SubQ: 30 million units/m 2 3 times/week
Chronic hepatitis B: I.M., SubQ: 5 million units/day or 10 million units 3 times/week for 16 weeks
Chronic hepatitis C: I.M., SubQ: 3 million units 3 times/week for 16 weeks. In patients with normalization of ALT at 16 weeks, continue treatment for 18-24 months; consider discontinuation if normalization does not occur at 16 weeks. Note: May be used in combination therapy with ribavirin in previously untreated patients or in patients who relapse following alpha interferon therapy; refer to Interferon Alfa-2b and Ribavirin Combination Pack monograph.
Condyloma acuminata: Intralesionally: 1 million units/lesion (maximum: 5 lesions/treatment) 3 times/week (on alternate days) for 3 weeks; may administer a second course at 12-16 weeks
Dosage adjustment for toxicity:
AST/ALT >5 times ULN: Permanently discontinue
Hairy cell leukemia:
Hepatitis B or C:
WBC <1000 cells/mm 3 , granulocytes <500 cells/mm 3 , or platelet count <25,000 cells/mm 3 : Permanently discontinue
Kaposi sarcoma: Severe toxicity: Reduce dose by 50% or temporarily discontinue
Neutrophils <250 cells/mm 3 or AST/ALT >10 times ULN: Permanently discontinue.
| Dosing (Adults):
Chronic hepatitis C: Recommended dosage of combination therapy:
Intron® A: SubQ: 3 million int. units 3 times/week and
Rebetol® capsule: Oral: </= 75 kg (165 lb): 1000 mg/day (two 200 mg capsules in the morning and three 200 mg capsules in the evening). >75 kg: 1200 mg/day (three 200 mg capsules in the morning and three 200 mg capsules in the evening)
Treatment duration recommendations:
Dosing adjustment for toxicity (adults):
Hemoglobin <8.5 g/dL: Permanently discontinue treatment
Patient with cardiac history:
Adults: Decrease dose to ribavirin to 600 mg/day and decrease interferon-alfa 2b dose to 1.5 million int. units 3 times/week.
Hemoglobin <12 g/dL after 4 weeks of reduced dose: Permanently discontinue treatment
WBC, neutrophil, or platelet depression:
WBC <1000 cells/mm 3 , neutrophils <500 cells/mm 3 , or platelet count <25,000 cells/mm 3 (<50,000 cells/mm 3 in children): Permanently discontinue therapy
Dosage adjustment in renal impairment:
Patients >/= 18 years of age: Intralesional treatment of refractory or recurring genital or venereal warts (condylomata acuminata)
DOSING (Adults): Inject 250,000 units (0.05 mL) in each wart twice weekly for a maximum of 8 weeks; therapy should not be repeated for at least 3 months after the initial 8-week course of therapy
Treatment of relapsing forms of multiple sclerosis (MS)
DOSING (Adults): Note: Analgesics and/or antipyretics may help decrease flu-like symptoms on treatment days:
SubQ (Rebif®): Doses should be separated by at least 48 hours:
Target dose 22 mcg 3 times/week:
Dosage adjustment in hepatic impairment: Rebif®: If liver function tests increase or in case of leukopenia: Decrease dose 20% to 50% until toxicity resolves
Injection, powder for reconstitution (Avonex®): 33 mcg [6.6 million units; provides 30 mcg/mL following reconstitution] [contains albumin; packaged with SWFI, alcohol wipes, and access pin and needle]
Injection, solution (Avonex®): 30 mcg/0.5 mL (0.5 mL) [albumin free; prefilled syringe; syringe cap contains latex; packaged with alcohol wipes, gauze pad, and adhesive bandages]
Injection, solution [preservative free] (Rebif®): 22 mcg/0.5 mL (0.5 mL) [prefilled syringe; contains albumin]; 44 mcg/0.5 mL (0.5 mL) [prefilled syringe; contains albumin]
Treatment of relapsing forms of multiple sclerosis (MS)
National Institutes of Health, U.S. National Library of Medicine, DailyMed Database.
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