Omalizumab

Identification

Name
Omalizumab
Accession Number
DB00043 / 2P471X1Z11
Groups
Xolair
Description

Omalizumab, synthetic by way of _Genentech_, was first FDA accredited in 2003 to treat adults and kids 12 years of age and older with moderate to intense chronic allergic allergies which isn't always managed by way of inhaled steroids [L4670]. when you consider that its U.S. approval, more than 2 hundred,000 sufferers older than 12 with allergic bronchial asthma had been treated [L4670]. In September 2018, a brand new prefilled syringe method of this drug turned into accredited by way of the FDA [L4671].

Pharmacology

Pharmacodynamics

Omalizumab is a recombinant, humanized, monoclonal antibody against human immunoglobulin E (IgE) which treats the symptoms of asthma and chronic idiopathic urticaria by limiting the allergic response [FDA label], [A39520]. It inhibits the binding of IgE to receptors on mast cells and basophils, blocking the IgE-mediated secretion of inflammatory mediators from these cells [A39518]. Mast cell activation and the release of mediators, in response to allergen exposure and IgE, results in a cascade of events. This cascade culminates in the activation of B-lymphocytes, T-lymphocytes, eosinophils, fibroblasts, smooth muscle cells, and the endothelium. This cellular interaction, as well as the release of cytokines, chemokines and growth factors and inflammatory remodeling of the airway results in chronic asthma [A39519]. After 4 weeks of use of this medication in patients with chronic urticaria, it was found that rescue medication use was reduced significantly and quality of life improved [A39521].

Indication

This drug is an anti-IgE antibody indicated for: 1. Moderate to severe persistent asthma in patients 6 years of age and older with a positive skin test or in vitro reactivity to a perennial aeroallergen and symptoms that are inadequately controlled with inhaled corticosteroids [FDA label] 2. Chronic idiopathic urticaria in adults and adolescents 12 years of age and older who remain symptomatic despite H1 antihistamine treatment [FDA label]

Action

When an environmental allergen first enters the body, is taken up by antigen-presenting cells (APCs). It is then processed, and presented to T and B immune cells. This is followed by the activation of B-lymphocyte and production of allergen-specific IgE. This IgE is then released by plasma cells (converted B lymphocytes) and is therefore available to bind to IgE receptors on several other cells [A39520]. IgE binds to high-affinity (Fc€RI) and low-affinity (Fc€RII) receptors on multiple cells of the immune system. Following subsequent antigen exposure, cross-linking of the antigen occurs by several Fc€RI-bound IgE molecules on the surface of both basophils and mast cells. This leads to the activation of mast cells and histamine release, producing a wheal and other symptoms of urticaria [A39520]. The following are explanations of the mechanism of action for both indications of this drug: **Asthma** Omalizumab inhibits the binding of IgE to the high-affinity IgE receptor (FcεRI) on the surface of both mast cells and basophils. The reduction in surface-bound IgE on FcεRI-bearing cells limits the degree of release of mediators of the typical allergic response. Treatment with omalizumab also reduces the number of FcεRI receptors on basophils in atopic patients [FDA label]. Omalizumab binds to free IgE with a higher affinity than IgE itself binds to the high-affinity Fc€RI receptors found on basophils. Therefore, it decreases the availability of free IgE for binding [A39520]. Omalizumab by itself does not bind to the Fc€RI receptors, nor does the drug bind to receptor-bound IgE. These binding characteristics allow omalizumab to neutralize the typical IgE-mediated responses without causing the degranulation of basophils or cross-linking with basophil-bound IgE [A39520]. **Chronic Idiopathic Urticaria** Omalizumab binds to IgE and decreases free IgE levels. Subsequently, IgE receptors (FcεRI) on cells are down-regulated. The mechanism by which these effects of omalizumab result in an improvement of CIU symptoms is unclear[FDA label].