Rheumatoid Arthritis (RA) ? Polyarticular Juvenile Idiopathic Arthritis (JIA) in patients aged 2 years or older ? Psoriatic Arthritis (PsA) ? Ankylosing Spondylitis (AS) ? Plaque Psoriasis (PsO)
Tumor necrosis factor (TNF) blocker
Etanercept is a tumor necrosis factor (TNF) blocker. This is a dimeric fusion protein consisting of the extracellular ligand-binding portion of the human 75 kilodalton (p75) tumor necrosis factor receptor (TNFR) linked to the Fc portion of human IgG1. The Fc component of etanercept contains the CH2 domain, the CH3 domain and hinge region, but not the CH1 domain of IgG1. Etanercept is produced by recombinant DNA technology in a Chinese hamster ovary (CHO) mammalian cell expression system. It consists of 934 amino acids and has an apparent molecular weight of approximately 150 kilodaltons. Etanercept is a TNF alpha inhibitor that binds specifically to tumor necrosis factor (TNF) and blocks its interaction with cell surface TNF receptors. TNF is a naturally occurring cytokine that is involved in normal inflammatory and immune responses. Elevated levels of TNF are found in the synovial fluid of RA patients. It plays an important role in the inflammatory processes of rheumatoid arthritis (RA), polyarticular-course juvenile rheumatoid arthritis (JRA) and the resulting joint pathology.
It is administered by subcutaneous injection. ? Adult RA and PsA 50 mg once weekly with or without methotrexate (MTX) ? AS 50 mg once weekly ? Adult PsO 50 mg twice weekly for 3 months, followed by 50 mg once weekly ? JIA 0.8 mg/kg weekly, with a maximum of 50 mg per week
Specific drug interaction studies have not been conducted. Vaccines
Most PsA patients receiving Enbrel were able to mount effective B-cell immune responses to pneumococcal
polysaccharide vaccine, but titers in aggregate were moderately lower and fewer patients had 2-fold rises in titers
compared to patients not receiving Enbrel. The clinical significance of this is unknown. Patients receiving Enbrel
may receive concurrent vaccinations, except for live vaccines. No data are available on the secondary transmission
of infection by live vaccines in patients receiving Enbrel.
Patients with a significant exposure to varicella virus should temporarily discontinue Enbrel therapy and be
considered for prophylactic treatment with varicella zoster immune globulin [see Warnings and Precautions (5.8,
5.10)].
7.2 Immune-Modulating Biologic Products
In a study in which patients with active RA were treated for up to 24 weeks with concurrent Enbrel and anakinra
therapy, a 7% rate of serious infections was observed, which was higher than that observed with Enbrel alone (0%)
[see Warnings and Precautions (5.12)] and did not result in higher ACR response rates compared to Enbrel alone.
The most common infections consisted of bacterial pneumonia (4 cases) and cellulitis (4 cases). One patient with
pulmonary fibrosis and pneumonia died due to respiratory failure. Two percent of patients treated concurrently with
Enbrel and anakinra developed neutropenia (ANC < 1 x 109
/L).
In clinical studies, concurrent administration of abatacept and Enbrel resulted in increased incidences of serious
adverse events, including infections, and did not demonstrate increased clinical benefit [see Warnings and
Precautions (5.12)].
7.3 Cyclophosphamide
The use of Enbrel in patients receiving concurrent cyclophosphamide therapy is not recommended. Sulfasalazine
Patients in a clinical study who were on established therapy with sulfasalazine, to which Enbrel was added, were noted to develop a mild decrease in mean neutrophil counts in comparison to groups treated with either Enbrel or
sulfasalazine alone. The clinical significance of this observation is unknown.
infections and injection site reactions.
Pregnancy Pregnancy Category B. Developmental toxicity studies have been performed in rats and rabbits at doses ranging from 60- to 100-fold higher than the human dose and have revealed no evidence of harm to the fetus due to Enbrel. There are, however, no studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Pregnancy Registry: To monitor outcomes of pregnant women exposed to Enbrel, a pregnancy registry has been established. Nursing Mothers It is not known whether Enbrel is excreted in human milk or absorbed systemically after ingestion. Because many drugs and immunoglobulins are excreted in human milk, and because of the potential for serious adverse reactions in nursing infants from Enbrel, a decision should be made whether to discontinue nursing or to discontinue the drug.
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