Peginterferon alfa-2a

Dose modifications: For moderate-to-severe adverse reactions: Initially, 135 mcg/wk or in some cases, 90 mcg/wk. Haematologic parameters: ANC <750/mm³: 135 mcg/wk; ANC <500/mm³: Discontinue therapy until >1000/mm³, then restart at 90 mcg/wk; monitor ANC. Platelet count: <50,000/mm³: 90 mcg/wk; <25,000/mm³: Discontinue therapy. Depression: Moderate: Decrease to 90-135 mcg once/wk; evaluate once wkly, if symptoms improve and remain stable for 4 wk, continue reduced dosing or return to normal dose; Severe: Discontinue treatment permanently. Administer in the abdomen or thigh.

Subcutaneous:
Chronic hepatitis C:
ESRD requiring haemodialysis: 135 mcg/wk; monitor for toxicity.

CrCl (mL/min)	Dosage
<50	Use caution; monitor for toxicity.

Chronic hepatitis B:
ESRD requiring haemodialysis: 135 mcg/wk; monitor for toxicity.

CrCl (mL/min)	Dosage
<50	Use caution; monitor for toxicity.

Subcutaneous:
Chronic hepatitis C: Alanine transaminase (ALT) progressively rising above baseline: Decrease dose to 135 mcg/wk. If ALT continues to rise or is accompanied by increased bilirubin or hepatic decompensation, discontinue immediately.
Chronic hepatitis B: Alanine transaminase (ALT) >5 times the upper limits of normal: Monitor LFTs more frequently; consider 135 mcg/wk or temporarily discontinuing (may resume after ALT flare subsides). ALT >10 times the upper limits of normal: Consider discontinuing.

Autoimmune hepatitis; decompensated liver disease in cirrhotic patients (Child-Pugh score >6); decompensated liver disease (Child-Pugh score ≥6, class B and C) in chronic hepatitis C coinfected with HIV; neonates and infants; in combination with ribavirin in pregnant women.

Neuropsychiatric disorders, discontinue treatment with worsening or persistently severe signs/symptoms; myelosuppresion; anemia (spherocytosis, history of GI bleeding); pulmonary disease; autoimmune disease; cardiovascular disease; DM; infectious disorders; ischaemic disorders; renal impairment; thyroid disorders; patients who have failed other alpha interferon therapy, received organ transplants, been coinfected with Hepatis B or C virus or HIV; or with Hepatitis C virus and HIV with a CD4+ cell count <100 cells/microliter, or been treated for >48 wk. Elderly. Safety and efficacy not been established in children. Do not change brands of interferon without the concurrence of healthcare provider (product variability). More frequent monitoring of LFTs and dose reduction in Hepatitis B. Hazardous agent, handle and dispose appropriately. May affect ability to drive or operate machinery.

Headache, fatigue, pyrexia, insomnia, depression, dizziness, irritability/anxiety/nervousness, pain; alopecia, pruritus, dermatitis; nausea/vomiting, anorexia, diarrhoea, weight loss, abdominal pain; neutropenia, lymphopenia, anemia; increase in alanine transaminase (ALT); inj site reaction; weakness, myalgia, rigors, arthralgia; dyspneal. Rarely: Impaired concentration, memory or mood; dermatitis, rash, dry skin, eczema; hypothyroidism, hyperthyroidism; xerostomia, dyspepsia, wt loss; thrombocytopenia, lymphopenia, anemia; hepatic decompensation; back pain; blurred vision; cough, dyspnea, exertional dyspnoea; diaphoresis, bacterial infection.
Potentially Fatal: Serious cutaneous reactions, including Stevens-Johnson syndrome; hepatic decompensation.

Parenteral/SC: X (when used in combination w/ ribavirin.)

Fatigue, elevated liver enzymes, neutropenia, thrombocytopenia; treatment is supportive.

Increased risk of haemolytic anemia, birth defects and/or foetal mortality, genotoxicity, mutagenicity, and may possibly be carcinogenic with ribavirin; decreases metabolism of theophylline; enhances adverse/toxic effects of zidovudine, decreases metabolism of zidovudine. Avoid ethanol in hepatitis C virus patients.

Description:
Mechanism of Action: Peginterferon alfa-2a are interferon proteins bound to polyethylene glycol (PEG) molecules resulting in higher and more prolonged serum interferon concentrations. It has antiviral, antiproliferative and immune-regulating activity. Interferons are activated when it interacts with cells through high affinity cell surface receptors. The effects of this activation include the induction of gene transcription, inhibition of cellular growth, alteration of cellular differentiation, interference with oncogene expression, alteration of cell surface antigen expression, increase in phagocytic activity of macrophages and augmentation of cytotoxicity of lymphocytes for target cells.
Pharmacokinetics:
Absorption: Time to peak (serum): 72-96 hr.
Excretion: Half-life elimination (terminal): 50-160 hr; increased with renal dysfunction.

Subcutaneous:
Chronic hepatitis C: Store in refrigerator at 2-8°C; do not freeze or shake. Protect from light.
Chronic hepatitis B: Storage: Store in refrigerator at 2-8°C; do not freeze or shake. Protect from light.

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