PEGINTERFERON ALFA-2A

PEGINTERFERON ALFA-2A
(peg-in-ter-fer'on)
Pegasys
Classifications: immunomodulator; interferon;
Therapeutic: immunomodulator
; interferon
Prototype: Interferon alfa-2a
Pregnancy Category: C

Availability

180 mcg/mL vials; 180 mcg prefilled syringes

Action

Interferon-stimulated genes modulate processes leading to inhibition of viral replication in infected cells, inhibition of cell proliferation, and immunomodulation. Stimulates production of effector proteins that raise body temperature, and causes reversible decreases in leukocyte and platelet counts.

Therapeutic Effect

Induces antiviral effects by activation of macrophages, natural killer cells, and T-cells, thus boosting cellular immunity and suppressing hepatic inflammation and replication of hepatitis C virus.

Uses

Chronic hepatitis C with or without ribavirin in patients coinfected with HIV; treatment of patients with BHeAg-positive or -negative chronic hepatitis B.

Contraindications

Hypersensitivity to peginterferon alfa-2a or any of its components; severe immunosuppression (e.g., organ transplant, advanced AIDS); autoimmune thyroid diseases (e.g., Graves' disease, thyroiditis); autoimmune hepatitis; dental work; sepsis; E. coli hypersensitivity, decompensated hepatic disease prior to or during treatment; in neonates and infants because it contains benzyl alcohol; females of childbearing age; lactation; pregnancy (category C).

Cautious Use

History of neuropsychiatric disorder; alcoholism, substance abuse, bipolar disorder, mania, psychosis; bone marrow suppression; cardiac arrhythmias, history of MI, cardiac disease, heart failure, uncontrolled hypertension; pulmonary disease, including COPD; thyroid dysfunction; diabetes mellitus, diabetic ketoacidosis; older adults; autoimmune disorders; autoimmune hepatitis; ulcerative and hemorrhagic colitis; pancreatitis; pulmonary disorders; HBV or HIV coinfection; retinal disease; renal impairment with creatinine clearance <50 mL/min; organ transplant recipients; lactation; children <18 y.

Route & Dosage

Chronic Hepatitis C
Adult: SC 180 mcg once weekly x 48 wk, may decrease to 135 mcg once weekly if not tolerated

Renal Impairment
End stage renal disease: reduce dose to 135 mcg once weekly.

Hepatic Impairment
Reduce dose to 90 mcg once weekly if LFTs progressively increase over baseline.

Administration

Subcutaneous
  • Give dose on the same day of each week. Administer SC in the abdomen or thigh and rotate injection sites.
  • Warm refrigerated vial by rolling in hands for about 1 min. Do not use if particulate matter is visible in the vial or product is discolored. Discard any unused portion.
  • Note that manufacturer recommends the following: dose reduction to 135 mcg if neutrophil count <750 cells/mm3 and with ANC values <500 cells/mm3, treatment should be suspended until ANC values return to more than 1000 cells/mm3; dose reduction to 90 mcg if the platelet count is <50,000 cells/mm3 and discontinuation of therapy if platelet count <25,000 cells/mm3. Consult physician.
  • Store in the refrigerator at 36°–46° F (2°–8° C), do not freeze or shake. Protect from light. Vials are for single use only.

Adverse Effects (≥1%)

Body as a Whole: Musculoskeletal pain, myalgia, arthralgia, fatigue, inflammation at injection site, flu-like symptoms, rigors, fever, pain, malaise, asthenia, exacerbation of autoimmune disease. CNS: Headache, depression, anxiety, irritability, insomnia, dizziness, impaired concentration, impaired memory, suicidal ideation, suicide attempt. GI: Nausea, diarrhea, abdominal pain, anorexia, dry mouth. Hematologic: Thrombocytopenia, neutropenia. Skin: Alopecia, pruritus, dermatitis, sweating, rash.

Interactions

Drug: May increase theophylline levels; increased risk of fetal defects with ribavirin; additive myelosuppression with antineoplastics.

Pharmacokinetics

Peak: 72–96 h. Elimination: 30% in urine. Half-Life: 80 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor for S&S of hypersensitivity (e.g., angioedema, bronchoconstriction) and, if noted, institute appropriate medical action immediately. Note that transient rashes are not an indication to discontinue treatment.
  • Withhold drug and notify physician for any of the following: severe neuropsychiatric events (e.g., psychosis, hallucinations, suicidal ideation, depression, bipolar disorders and mania), severe neutropenia or thrombocytopenia, abdominal pain accompanied by bloody diarrhea and fever, S&S of pancreatitis, new or worsening ophthalmologic disorders, or any other severe adverse event (see CAUTIOUS USE).
  • Withhold drug and notify physician for any of the following: Baseline neutrophil counts <1500 cells/mm3, baseline platelet counts <90,000 cells/mm or baseline hemoglobin <10 g/dL.
  • Note that acceptable baseline limits for therapy include: Platelet count ≥90,000 cells/mm3 (as low as 75,000 cells/mm3 in patients with cirrhosis or transition to cirrhosis), absolute neutrophil count (ANC) ≥1500 cells/mm3; serum creatinine <1.5 x upper limit of normal; TSH and T4 within normal limit. Withhold therapy and notify physician for unacceptable baseline values.
  • Monitor respiratory and cardiovascular status; report dyspnea, chest pain, and hypotension immediately; perform baseline and periodic ECG and chest X-ray.
  • Lab tests: Baseline and periodic creatinine clearance, uric acid, CBC with differential, platelet count, Hct & Hgb, TSH, ALT, AST, bilirubin, blood glucose; retest CBC with differential, platelet count, Hct & Hgb after 2 wk and other blood chemistries after 4 wk. Serum HCV RNA levels after 24 wk of treatment.
  • Baseline and periodic ophthalmology exams are recommended.

Patient & Family Education

  • If you miss a drug dose and remember within 2 d of the scheduled dose, take the dose and continue with your regular schedule. If more than 2 d have passed, contact physician for instructions.
  • Notify physician immediately for any of the following: severe depression or suicidal thoughts, severe chest pain, difficulty breathing, changes in vision, unusual bleeding or bruising, bloody diarrhea, high fever, severe stomach or lower back pain, severe chest pain, development a new or worsening of a preexisting skin condition.
  • Follow up with lab tests; compliance with lab testing is extremely important while taking this drug.
  • Do not drive or engage in other potentially hazardous activities until reaction to drug is known.
  • Women should use reliable means of contraception while taking this drug and notify physician immediately if they become pregnant.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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