Avonex / Plegridy

Interferon Beta 1a


Before Initiation of Therapy :
  • CBC, liver enzymes, bilirubin, TSH
  •  HBsAg, anti-HBc, anti-HBs, Hepatits C, HIV, VZV serology
  • Vaccination status verified and updated if necessary
  • Negative pregnancy test and counsel with regards to contraception
Avonex Titration Schedule (intramuscular injection) :
  • Week 1 1/4 dose (approximately 7.5 μg)
  • Week 2 1/2 dose (approximately 15 μg)
  • Week 3 3/4 dose (approximately 22.5 μg)
  • Week 4+ Full dose (30 μg) and every week thereafter
Plegridy Titration Schedule (subcutaneous injections) :

It is recommended that patients start treatment with 63 micrograms (orange syringe) at dose 1 (on day 0) increasing to 94 micrograms (blue syringe) at dose 2 (on day 14) reaching the full dose of 125 micrograms (grey syringe) by dose 3 (on day 28) and continuing with the full dose (125 micrograms) every 14 days thereafter.

A Starter Pack is available containing the first 2 doses, 63 micrograms (dose 1, orange labeled syringe/pen) and 94 micrograms (dose 2, blue labeled syringe/pen) for day 0 and day 14 respectively. Patients should use the Administration Dose Pack containing the full dose of 125 micrograms (full dose, grey labeled syringe/pen) from day 28 onwards (dosing every 14, days).

A patient should not administer two doses of PLEGRIDY within 7 days of each other.

Monitoring During Therapy :
  • CBC, Liver enzymes, bilirubin Q1month X6 then Q4 months
  • TSH Q6 months
  • Nabs any time after 12 months
Discontinue Therapy :
  • ALT>5X ULN or jaundice
  • Nabs (+) (2 -6 %)
  • Severe thrombocytopenia especially in setting of fever and encephalopathy (R/O TTP)
  • Severe leukopenia or pancytopenia
  • Depression or suicidal ideation
  • Unexplained cardiomyopathy with /out congestive heart failure
  • Pregnancy
  • Seizure

Product Monograph

Specific Concerns

Storage :

Should be stored in a refrigerator but can be kept at room temperature for up to one week. Extremes in        temperature and exposure to ligth should be avoided.

Patient Selection :

Should be used with caution in patients with prior seizure disorder, liver disease, ongoing depression or concomitantly with other potentially liver toxic therapies

Adverse Events :

  • Most frequent adverse event is flu like symptoms which tend to diminish in severity and frequency with time
  • Decreased peripheral blood counts in all cell lines, including very rare pancytopenia and thrombocytopenia have been reported from post-marketing experience
  • Elevated liver enzymes from hepatic injury or hepatitis including hepatic failure have been reported
  • Can lead to autoimmune disorders such as drug induced SLE, autoimmune hepatitis, hyper or hypothyroidism, thrombotic thrombocytopenic purpura  and haemolytic uraemic syndrome. These events can may occur after several weeks to several years after starting treatment with interferon beta.
  • Anaphylaxis has been reported as a rare complication. Other allergic reactions have included dyspnea, orolingual edema, skin rash and urticaria
  • Cases of nephrotic syndrome with different underlying nephropathies including collapsing focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), membranoproliferative glomerulonephritis (MPGN) have been reported during treatment with interferon-beta products.
  • Rare cases of secondary systemic capillary leak sydrome (Clarkson syndrome) has been reported with interferon beta administration to patients with underlying monoclonal gammopathy

Neutralizing Antibodies :

Serum neutralizing antibodies (Nabs) were reported to develop in 2% to 6% of patients. persitent Nabs tend to occur by the end of the first year of treatment. they have been shown to impact clinical efficacy and MRI measures.