interferon beta 1a (Avonex, Rebif, Rebif Rebidose, AVOSTARTGRIP)
Dosing and uses of Avonex, Rebif (interferon beta 1a)
Adult dosage forms and strengths
prefilled IM syringe (Avonex)
- 30mcg/0.5mL
prefilled IM autoinjector pen (Avonex)
- 30mcg/0.5mL
powder for injection (Avonex)
- 30mcg/vial (30mcg/0.5 mL reconstituted)
prefilled SC syringes titration pack (Rebif)
- 8.8mcg/0.2mL (6 syringes)
- 22mcg/0.5mL (6 syringes)
prefilled SC syringe (Rebif)
- 22mcg/0.5mL
- 44mcg/0.5mL
prefilled SC autoinjector (Rebif Rebidose)
- 8.8mcg/syringe
- 22mcg/syringe
- 44mcg/syringe
Multiple Sclerosis
Indicated for the treatment of relapsing forms of multiple sclerosis to slow accumulation of physical disability and decrease frequency of clinical exacerbations
Avonex
- 30 mcg IM qWk
- May be titrated using the AVOSTARTGRIP titration kit with prefilled IM syringes starting with 7.5 mcg IM for first week, to reduce flu-like symptoms; increase by 7.5 mcg/week for next 3 weeks until recommended dose of 30 mcg/week
- Administration: Rotate IM injection sites between upper thighs and arms
Rebif 44 mcg target dose
- Weeks 1-2: 8.8 mcg SC 3 times/wk (at least 48 hr apart)
- Weeks 3-4: 22 mcg SC 3 times/wk
- Weeks 5+: 44 mcg SC 3 times/wk
- Administration: Abdomen (except waistline), thigh, arm, buttocks
Rebif 22 mcg target dose
- Weeks 1-2: 4.4 mcg SC 3 times/wk (at least 48 hr apart)
- Weeks 3-4: 11 mcg SC 3 times/wk
- Weeks 5+: 22 mcg SC 3 times/wk
- Administration: Abdomen (except waistline), thigh, arm, buttocks
Hepatic Impairment
Rebif: Decrease dose 20-50% if liver function tests increase or leukopenia observed
Pediatric dosage forms and strengths
prefilled IM syringe (Avonex)
- 30mcg/0.5 mL
prefilled IM autoinjector pen (Avonex)
- 30mcg/0.5mL
powder for injection (Avonex)
- 30mcg/vial (30mcg/0.5 mL reconstituted)
prefilled SC syringes titration pack (Rebif)
- 8.8mcg/0.2mL (6 syringes)
- 22mcg/0.5mL (6 syringes)
prefilled SC syringe (Rebif)
- 22mcg/0.5mL
- 44mcg/0.5mL
prefilled SC autoinjector (Rebif Rebidose)
- 8.8mcg/syringe
- 22mcg/syringe
- 44mcg/syringe
Multiple Sclerosis (Off-label)
Safety and efficacy not established
Limited data suggests to titrate as in adults
Avonex
- 30 mcg IM qWk
- May be titrated using the AVOSTARTGRIP titration kit with prefilled IM syringes starting with 7.5 mcg IM for first week, to reduce flu-like symptoms; increase by 7.5 mcg/week for next 3 weeks until recommended dose of 30 mcg/week
- Administration: Rotate IM injection sites between upper thighs and arms
Rebif 44 mcg target dose
- Weeks 1-2: 8.8 mcg SC 3 times/wk (at least 48 hr apart)
- Weeks 3-4: 22 mcg SC 3 times/wk
- Weeks 5+: 44 mcg SC 3 times/wk
- Administration: Abdomen (except waistline), thigh, arm, buttocks
Rebif 22 mcg target dose
- Weeks 1-2: 4.4 mcg SC 3 times/wk (at least 48 hr apart)
- Weeks 3-4: 11 mcg SC 3 times/wk
- Weeks 5+: 22 mcg SC 3 times/wk
- Administration: Abdomen (except waistline), thigh, arm, buttocks
- Monitor: Hgb, WBC, Plt, LFTs
Geriatric dosage forms and strengths
Multiple sclerosis
Avonex
30 mcg IM qWk
May be titrated using the AVOSTARTGRIP titration kit with prefilled IM syringes starting with 7.5 mcg IM for first week, to reduce flu-like symptoms; increase by 7.5 mcg/week for next 3 weeks until recommended dose of 30 mcg/week
Administration: Rotate IM injection sites between upper thighs and arms
Monitor: Hgb, WBC, Plt, LFTs
Rebif 44 mcg target dose
Weeks 1-2: 8.8 mcg SC 3 times/wk (at least 48 hr apart)
Weeks 3-4: 22 mcg SC 3 times/wkWeeks 5+: 44 mcg SC 3 times/wk
Administration: Abdomen (except waistline), thigh, arm, buttocks
Monitor: Hgb, WBC, Plt, LFTs
Rebif 22 mcg target dose
Weeks 1-2: 4.4 mcg SC 3 times/wk (at least 48 hr apart)
Weeks 3-4: 11 mcg SC 3 times/wk
Weeks 5+: 22 mcg SC 3 times/wk
Administration: Abdomen (except waistline), thigh, arm, buttocks
Monitor: Hgb, WBC, Plt, LFTs
Avonex, Rebif (interferon beta 1a) adverse (side) effects
>10%
Injection site reactions (83% [Rebif]; 28% [Avonex])
Headache (67%)
Flu-like syndrome (61%)
Muscle ache (34%)
Nausea (33%)
URT infection (14%)
Pain (24%)
Fever (23%)
Asthenia (21%)
Diarrhea (16%)
Dizziness (15%)
Infection (11%)
Dyspepsia (11%)
1-10%
Abdominal pain (9%)
Anemia (8%)
Chest pain (6%)
<1%
Aggravation of seizure disorders
Postmarketing Reports
Autoimmune disorders: Drug-induced lupus erythematosus, autoimmune hepatitis
Blood and lymphatic system disorders: Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS)
Eye disorders: Retinal vascular disorders (ie, retinopathy, cotton wool spots or obstruction of retinal artery or vein)
Skin and subcutaneous tissue disorders: Erythema multiforme, Stevens-Johnson syndrome
Hyperhidrosis
Warnings
Contraindications
Hypersensitivity to beta interferons, albumin (for albumin-containing formulations)
Cautions
Hepatic impairment, pregnancy, lactation, depression (may cause worsening, suicidal ideation)
Risk of rare but potentially severe hepatic damage
Fllu-like symptoms may occur
Caution in patients with existing cardiovascular disease (angina, heart failure, etc)
Autoimmune disorders (autoimmune hepatitis; idiopathic thrombocytopenia) reported
Efficacy in primary progressive MS not demonstrated conclusively; not recommended
Cases of thrombotic microangiopathy, including thrombotic thrombocytopenic purpura and hemolytic uremic syndrome, some fatal, reported; some cases have been reported several weeks to years after starting interferon beta products; discontinue therapy if clinical symptoms and laboratory findings consistent with TMA occur, and manage as clinically indicated
Pregnancy and lactation
Pregnancy category: C
Lactation: unknown; use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Avonex, Rebif (interferon beta 1a)
Mechanism of action
Recombinant interferon; antiviral, antiproliferative, immunoregulatory protein; alters response to surface antigen and may enhance immune cell activities
Pharmacokinetics
Onset of action: 12 hr (Avonex)
Duration: 4 days (Avonex)
Peak plasma time: 7.8-9.8 hr (IM); 16 hr (SC)
Concentration: 5.1±1.7 IU/mL (SC)
AUC: 294±81 IU.hr/mL (SC)
Half-Life: 8.6-10 hr (IM); 69±37 hr (SC)
Clearance: 33-55 L/hr (SC)
