NOTE: The discussion of safety / adverse effects herein focusses on key topics, and is NOT exhaustive. Please consult the official product monograph.
MECHANISM OF ACTION
- Etanercept is a recombinant DNA-derived protein comprised of Tumor Necrosis Factor Receptor (TNF-R) linked to the Fc portion of human IgG1. Etanercept binds TNF and blocks its interaction with cell surface receptors.
- Rheumatoid arthritis (RA), Psoriatic Arthritis (PsA), Ankylosing Spondylitis (AS), Psoriasis (PsO)
- RA, PsA, AS: 50 mg subcutaneously once weekly
- PsO: 50 mg subcutaneously twice weekly x 3 months, then once weekly
Hepatic Impairment: No dose adjustments provided in product monograph
Renal Impairment: No dose adjustments provided in product monograph
SCREENING PRIOR TO STARTING THERAPY
- Screening for Latent Tuberculosis: CXR, TB skin test.
- Patients with Latent TB (skin test ≥ 5 mm, negative CXR) must receive TB prophylaxis. Etanercept can be started one month after prophylaxis is started.
- If TB skin test is thought to be false negative (eg. high endemic risk) or false positive (eg. BCG vaccine), IGRA should be performed.
- Hepatitis screening: Hep B sAg, Hep B cAb, Hep C Ab
Patients with chronic inflammatory / rheumatic disease have an increased risk of infection. Vaccinations should be considered at earlier ages than that prescribed for the general population. Ideally, the following vaccines should be considered in patients prior to starting biologics, especially patients over 50. However, depending on disease severity, one may need to proceed with biologic therapy and vaccinate along the way (most frequent scenario in clinical practice). Data suggests reduced vaccine response (antibody titres) while on some DMARDS / Biologics, but this has not been shown to result in increased risk of infection.
- Pneumonia: Prevnar 13, Pneumovax (given two months apart in this order). If Pneumovax was received first, wait one year before giving Prevnar 13.
- Shingles: Shingrix (two doses given 2-6 months apart; biologic can be started 2 weeks after the first dose). Shingrix is preferred over the (older) live attenuated Zostavax vaccine. If Zostavax is used, it must be given at least 2 weeks prior to starting biologics.
- Annual flu vaccine
- Patients with rheumatic diseases on biologics are typically re-assessed clinically every 3-6 months, with investigations performed as clinically indicated.
WHEN TO AVOID
- Etanercept should be avoided in patients with active infection, active malignancy, hypersensitivity to etanercept / components.
SIDE EFFECTS AND ADVERSE REACTIONS
- Infection: the risk of infection is considered to be very low, but serious infections have been reported in patients on biologic therapy. When considering therapy, this has to be balanced against the increased risk of infection caused by active rheumatic / inflammatory disease. Risk of infection is also confounded by use of concomitant DMARDS and prednisone. Advise patients with symptoms of infection to hold the biologic, seek medical attention,and do not resume until one week after recovery.
- Reactivation of Latent TB (see above), Hepatis B reactivation
- Malignancy: Except for a 2-3 fold increase in the risk of skin cancer (melanoma and non-melanoma), data suggests that there is no increase in the risk of solid tumours. Registry data suggests that the risk of lymphoma is driven by the underlying disease, and not by biologic medications.
- Rare reports of demyelinating disease, autoimmune (lupus-like) diseases, interstitial lung disease, congestive heart failure (especially patients with preceding class III/IV heart failure)
- Emerging evidence suggests that Etanercept is safe in pregnancy, and current practice is to continue it throughout pregnancy. In general, the risk of untreated rheumatic disease to the developing fetus and to maternal health is considered to be greater than the risk of Etanercept itself.
- Etanercept crosses the placenta. Use during the 3rd trimester can be associated with immunosuppression in the newborn during the first 3 months. Live attenuated vaccines must be avoided in the newborn for the first 6 months.
- Etanercept is present in breast milk, but is considered to be compatible with breast feeding.