FASENRA
Clinical safety rating
cautionComprehensive clinical and safety monograph for FASENRA (FASENRA).
Comprehensive clinical and safety monograph for FASENRA (FASENRA).
Add-on maintenance treatment of patients with severe asthma aged 12 years and older, and with an eosinophilic phenotype
Benralizumab is a humanized afucosylated monoclonal antibody that binds to the alpha subunit of the interleukin-5 receptor (IL-5Rα) expressed on eosinophils and basophils. This binding inhibits IL-5-mediated signaling and induces antibody-dependent cell-mediated cytotoxicity (ADCC), resulting in rapid and near-complete depletion of eosinophils from blood and tissues.
| Metabolism | Benralizumab is a monoclonal antibody degraded into small peptides and amino acids via catabolic pathways, primarily by reticuloendothelial system. No specific metabolic enzymes involved. |
| Excretion | Degraded into small peptides and amino acids via general protein catabolism; no significant renal or biliary/fecal excretion of intact drug. |
| Half-life | Terminal half-life approximately 25 days (range 24–27 days), supporting every-4-week subcutaneous dosing. |
| Protein binding | Approximately 99% bound to target IL-5 receptor alpha; not bound significantly to other plasma proteins. |
| Volume of Distribution | Approximately 3.0–3.5 L (0.04 L/kg for a 70 kg patient), indicating primarily vascular distribution with limited extravascular penetration. |
| Bioavailability | Subcutaneous: 66–82% (mean 73%) following SC injection; not administered intravenously. |
| Onset of Action | Subcutaneous: Reduction in blood eosinophil counts observed within 24 hours; clinical improvement in asthma symptoms may be noted within 4 weeks. |
| Duration of Action | Eosinophil suppression persists for at least 12 weeks after single dose; dosing every 4 weeks maintains therapeutic effect. |
| Molecular Weight | 150 kDa |
30 mg subcutaneously every 4 weeks for the first 3 doses, then every 8 weeks thereafter.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for any degree of renal impairment. |
| Liver impairment | No dose adjustment required for mild or moderate hepatic impairment (Child-Pugh A or B); not studied in severe hepatic impairment (Child-Pugh C). |
| Pediatric use | Approved for ages 12 years and older: same as adult dosing (30 mg subcutaneously every 4 weeks for 3 doses, then every 8 weeks). |
| Geriatric use | No specific dose adjustment recommended; limited data in patients ≥65 years, but no overall differences in safety or efficacy observed. |
| 1st trimester | There are no adequate and well-controlled studies in pregnant women. However, based on its mechanism of action as a monoclonal antibody, IgG antibodies are known to cross the placenta in increasing amounts as pregnancy progresses, with the largest amount transferred during the third trimester. The drug should be used during the first trimester only if the potential benefit justifies the potential risk to the fetus. |
| 2nd trimester | Similar to first trimester, there are no adequate studies. Use only if clearly needed. |
| 3rd trimester | IgG antibodies cross the placenta in increasing amounts as pregnancy progresses, with the largest amount transferred during the third trimester. Caution is advised, but the drug may be used if the potential benefit outweighs the potential risk. |
Clinical note
Comprehensive clinical and safety monograph for FASENRA (FASENRA).
| Placental transfer | As a humanized monoclonal antibody (IgG1), benralizumab is expected to cross the placenta. Placental transfer of IgG antibodies increases as pregnancy progresses, with the greatest transfer occurring in the third trimester. |
| Breastfeeding | It is not known whether benralizumab is excreted in human milk. However, monoclonal antibodies are expected to be present in breast milk in low amounts. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for FASENRA and any potential adverse effects on the breastfed child from the drug or from the underlying maternal condition. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | No adequate human data; animal studies show no evidence of fetal harm at doses up to 100 mg/kg IV (monoclonal antibody). IgG crosses placenta increasingly in second and third trimesters; potential for fetal immune suppression. Risk cannot be ruled out. |
| Fetal Monitoring | Monitor for maternal infections; fetal growth and well-being via ultrasound if used in pregnancy. Assess neonatal immune function at birth if exposed in utero. |
| Fertility Effects | No specific fertility studies; in animal studies, no adverse effects on male or female fertility at doses up to 100 mg/kg IV. |
■ FDA Black Box Warning
None
| Serious Effects |
History of hypersensitivity to benralizumab or any of its excipients
| Precautions | Hypersensitivity reactions (including anaphylaxis, angioedema, urticaria, rash) have occurred after administration., Acute asthma symptoms or deteriorating disease should not be treated with FASENRA., Risk of parasitic infections: Patients with pre-existing helminth infections should be treated before initiating therapy. Monitor for infection during treatment., Do not discontinue systemic or inhaled corticosteroids abruptly upon initiation of FASENRA. |
| Food/Dietary | No known food interactions. No dietary restrictions required. |
| Clinical Pearls | FASENRA (benralizumab) is an IL-5Rα antagonist for add-on maintenance treatment of severe eosinophilic asthma. Administer subcutaneously every 4 weeks for first 3 doses, then every 8 weeks. Do not use for acute exacerbations. Monitor for hypersensitivity reactions including anaphylaxis. Consider tapering systemic corticosteroids after improvement. May reduce oral corticosteroid use. Not recommended for other eosinophilic conditions. |
| Patient Advice | Do not use to treat sudden breathing problems or asthma attacks. · Seek immediate medical help if you experience symptoms of an allergic reaction (hives, rash, swelling, difficulty breathing). · Inform your healthcare provider about all medications you take, including corticosteroids. · You may need to continue other asthma medications as prescribed. · Typical dosing: three initial doses every 4 weeks, then one injection every 8 weeks. · Do not stop corticosteroids abruptly without medical advice. · Store in refrigerator at 2-8°C (36-46°F) in original carton; protect from light. Do not freeze or shake. · If a dose is missed, administer as soon as possible; adjust schedule accordingly. |
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