SYLATRON

Clinical safety rating: caution

Comprehensive clinical and safety monograph for SYLATRON (SYLATRON).

How it works

Peginterferon alfa-2b binds to type I interferon receptors, activating JAK-STAT signaling and inducing expression of antiviral, antiproliferative, and immunomodulatory proteins.

What the body does with it

Metabolism	Peginterferon alfa-2b is primarily metabolized by proteolytic degradation; renal clearance contributes to elimination.
Excretion	Renal clearance is the primary route of elimination for peginterferon alfa-2b. Approximately 30% of the dose is excreted unchanged in urine, with the remainder metabolized and excreted via bile/feces.
Half-life	Terminal elimination half-life is approximately 40 hours (range 27-60 hours) following subcutaneous administration. This prolonged half-life supports once-weekly dosing.
Protein binding	Approximately 95% bound to albumin; binding is independent of drug concentration.
Volume of Distribution	Mean volume of distribution is 0.99 L/kg (range 0.5-1.5 L/kg), indicating distribution primarily into extracellular fluid and tissues.
Bioavailability	Subcutaneous bioavailability is approximately 100% (nearly complete absorption).
Onset of Action	Subcutaneous administration: Induction of antiviral and antiproliferative effects begins within 24 hours, with peak serum concentrations achieved at 15-44 hours post-dose.
Duration of Action	Duration of action is approximately 1 week, consistent with once-weekly dosing. Clinical effects (e.g., antiviral activity, hematologic changes) persist throughout the dosing interval.

Classification & Brands

Dosing & administration

200 mcg/kg subcutaneously once weekly for 1 year in combination with oral ribavirin.

Dosage form	VIAL
Renal impairment	CrCl <50 mL/min: contraindicated. No dose adjustment required for mild impairment (CrCl 50-80 mL/min) but monitor closely. End-stage renal disease (CrCl <10 mL/min): not recommended.
Liver impairment	Contraindicated in patients with decompensated liver disease (Child-Pugh class B or C). No formal studies in mild hepatic impairment; use with caution.
Pediatric use	Safety and efficacy not established in patients <18 years. Not recommended.
Geriatric use	No specific dose adjustment, but older patients may have decreased renal function; monitor renal function and dose accordingly. Higher incidence of adverse effects (fatigue, neuropsychiatric) reported in elderly.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for SYLATRON (SYLATRON).

Breastfeeding

It is unknown if peginterferon alfa-2b is excreted in human milk. Many interferons are excreted in breast milk in animals. Due to potential for serious adverse reactions in nursing infants, breastfeeding is not recommended during treatment and for 10 months after last dose. M/P ratio not available.

Teratogenic Risk

Peginterferon alfa-2b (SYLATRON) is contraindicated in pregnancy. Based on animal studies and its mechanism of action, there is a potential for fetal harm. Interferons have abortifacient effects in primates. First trimester: high risk of miscarriage. Second and third trimesters: possible fetal growth restriction, developmental toxicity. Use effective contraception during therapy and for 10 months after last dose.

Warnings & precautions

■ FDA Black Box Warning

May cause or aggravate neuropsychiatric, autoimmune, ischemic, and infectious disorders; patients should be closely monitored.

Side Effect Profile

Serious Effects

Absolute Contraindications

History of hypersensitivity to interferon alfa-2b or any component; autoimmune hepatitis; decompensated liver disease; pre-existing severe psychiatric disorders (especially depression).

Clinical Precautions

Precautions

Risk of neuropsychiatric reactions (depression, suicidality), autoimmune disorders (thyroid dysfunction, psoriasis), cardiovascular events (ischemia), pulmonary toxicity, and ophthalmologic disorders.

Clinical Tips & Counseling

Drug interactions

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SYLATRON

Clinical safety rating: caution

Comprehensive clinical and safety monograph for SYLATRON (SYLATRON).

How it works

Peginterferon alfa-2b binds to type I interferon receptors, activating JAK-STAT signaling and inducing expression of antiviral, antiproliferative, and immunomodulatory proteins.

What the body does with it

Metabolism	Peginterferon alfa-2b is primarily metabolized by proteolytic degradation; renal clearance contributes to elimination.
Excretion	Renal clearance is the primary route of elimination for peginterferon alfa-2b. Approximately 30% of the dose is excreted unchanged in urine, with the remainder metabolized and excreted via bile/feces.
Half-life	Terminal elimination half-life is approximately 40 hours (range 27-60 hours) following subcutaneous administration. This prolonged half-life supports once-weekly dosing.
Protein binding	Approximately 95% bound to albumin; binding is independent of drug concentration.
Volume of Distribution	Mean volume of distribution is 0.99 L/kg (range 0.5-1.5 L/kg), indicating distribution primarily into extracellular fluid and tissues.
Bioavailability	Subcutaneous bioavailability is approximately 100% (nearly complete absorption).
Onset of Action	Subcutaneous administration: Induction of antiviral and antiproliferative effects begins within 24 hours, with peak serum concentrations achieved at 15-44 hours post-dose.
Duration of Action	Duration of action is approximately 1 week, consistent with once-weekly dosing. Clinical effects (e.g., antiviral activity, hematologic changes) persist throughout the dosing interval.

Classification & Brands

Dosing & administration

200 mcg/kg subcutaneously once weekly for 1 year in combination with oral ribavirin.

Dosage form	VIAL
Renal impairment	CrCl <50 mL/min: contraindicated. No dose adjustment required for mild impairment (CrCl 50-80 mL/min) but monitor closely. End-stage renal disease (CrCl <10 mL/min): not recommended.
Liver impairment	Contraindicated in patients with decompensated liver disease (Child-Pugh class B or C). No formal studies in mild hepatic impairment; use with caution.
Pediatric use	Safety and efficacy not established in patients <18 years. Not recommended.
Geriatric use	No specific dose adjustment, but older patients may have decreased renal function; monitor renal function and dose accordingly. Higher incidence of adverse effects (fatigue, neuropsychiatric) reported in elderly.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for SYLATRON (SYLATRON).

Breastfeeding

Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

May cause or aggravate neuropsychiatric, autoimmune, ischemic, and infectious disorders; patients should be closely monitored.

Side Effect Profile

Serious Effects

Absolute Contraindications

History of hypersensitivity to interferon alfa-2b or any component; autoimmune hepatitis; decompensated liver disease; pre-existing severe psychiatric disorders (especially depression).