PEGINTRON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PEGINTRON (PEGINTRON).
Recombinant interferon alfa-2b conjugated to polyethylene glycol; binds to interferon receptors, inducing antiviral, antiproliferative, and immunomodulatory effects via JAK-STAT signaling pathway.
| Metabolism | Primarily hepatic metabolism via nonspecific proteolysis; CYP450-mediated metabolism negligible. |
| Excretion | Renal: 30% unchanged; biliary/fecal: 70% as metabolites and parent drug |
| Half-life | Terminal half-life: 40 hours (range 30-50 h) after subcutaneous dosing; supports weekly dosing regimen |
| Protein binding | ~90% (primarily to albumin and alpha-1 acid glycoprotein) |
| Volume of Distribution | 0.8-1.0 L/kg (central compartment, indicating limited extravascular distribution) |
| Bioavailability | Subcutaneous: ~60-70% (absolute bioavailability) |
| Onset of Action | Subcutaneous: 24-48 hours (based on viral load reduction); IV: immediate |
| Duration of Action | Weekly dosing maintains therapeutic effect; clinical response assessed at 12 and 24 weeks |
1.5 mcg/kg subcutaneously once weekly in combination with oral ribavirin.
| Dosage form | SYRINGE |
| Renal impairment | CrCl 30-50 mL/min: reduce dose to 1.0 mcg/kg once weekly; CrCl 15-29 mL/min: 0.5 mcg/kg once weekly; CrCl <15 mL/min or hemodialysis: contraindicated. |
| Liver impairment | Child-Pugh class A: no adjustment; Child-Pugh class B: reduce dose by 25%; Child-Pugh class C: contraindicated. |
| Pediatric use | 3-17 years: 60 mcg/m² subcutaneously once weekly in combination with ribavirin; dose not exceed adult doses. |
| Geriatric use | No specific dose adjustment; monitor renal function and consider age-related decline in CrCl; evaluate for ribavirin-induced anemia more frequently. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PEGINTRON (PEGINTRON).
| Breastfeeding | It is unknown whether peginterferon alfa-2b is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when administered to a nursing woman. The M/P ratio is not established for peginterferon alfa-2b; for interferon alfa, the M/P ratio in rats is 1.5, but human data are lacking. Due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. |
| Teratogenic Risk | Peginterferon alfa-2b (PEGINTRON) is classified as Pregnancy Category C. In animal studies, interferon alfa has been shown to have abortifacient effects. There are no adequate and well-controlled studies in pregnant women. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. Exposure in the first trimester may carry increased risk of spontaneous abortion. Fetal risks in second and third trimesters are not well characterized but may include growth restriction. |
■ FDA Black Box Warning
["Risk of serious neuropsychiatric disorders, including suicide and suicidal ideation","Risk of bone marrow suppression, particularly neutropenia and thrombocytopenia","Risk of autoimmune disorders, including thyroid abnormalities and diabetes","Risk of ischemic and hemorrhagic cerebrovascular events"]
| Serious Effects |
["History of severe neuropsychiatric disorders (e.g., major depression, suicidal ideation)","Autoimmune hepatitis or other autoimmune disorders","Decompensated liver disease (Child-Pugh class B or C)","Known hypersensitivity to interferon alfa-2b or any component","Pregnancy (when used in combination with ribavirin; ribavirin is teratogenic)"]
| Precautions | ["May cause or aggravate neuropsychiatric reactions; monitor for depression and suicidal ideation","May cause bone marrow suppression; monitor CBCs regularly","May induce autoimmune disorders; monitor thyroid function and glucose levels","May cause cardiovascular events; use caution in patients with pre-existing cardiac disease","May cause hepatic decompensation in cirrhosis patients; monitor liver function","May cause ophthalmic disorders; perform eye exams if symptoms occur"] |
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| Fetal Monitoring | Monitor complete blood counts (CBC) with differential, platelet counts, and liver function tests (LFTs) regularly. Thyroid-stimulating hormone (TSH) should be monitored every 3 months during therapy. In pregnant patients, fetal growth ultrasound is recommended if treatment continues during the second and third trimesters. Monitor for signs of depression or neuropsychiatric adverse effects. |
| Fertility Effects | Peginterferon alfa-2b may impair fertility. In animal studies, interferon alfa reduced fertility in female monkeys. Men receiving peginterferon may have decreased sperm count and motility. Reversible oligospermia has been reported in men treated with interferon alfa. Women may experience menstrual irregularities and amenorrhea. |