Eculizumab specifically binds to the terminal complement component 5, or C5, which acts at a late stage in the complement cascade. When activated, C5 is involved in activating host cells, thereby attracting pro-inflammatory immune cells, while also destroying cells by triggering pore formation. By inhibiting the complement cascade at this point, the normal, disease-preventing functions of proximal complement system are largely preserved, while the properties of C5 that promote inflammation and cell destruction are impeded.

Eculizumab inhibits the cleavage of C5 by the C5 convertase into C5a a potent anaphylatoxin with prothrombotic and proinflammatory properties, and C5b, which then forms the terminal complement complex C5b-9 which also has prothrombotic and proinflammatory effects. Both C5a and C5b-9 cause the complement-mediated events that are characteristic of PNH and aHUS. The metabolism of eculizumab is thought to occur via lysosomal enzymes that cleave the antibody to generate small peptides and amino acids. The volume of distribution of eculizumab in humans approximates that of plasma.

Eculizumab is a recombinant humanized monoclonal antibody against the complement protein C5. It is an immunoglobulin G-kappa (IgGκ) consisting of human constant regions and murine complementarity-determining regions grafted onto human framework light and heavy chain variable regions. The compound contains two 448-amino acid heavy chains and two 214-amino acid light chains, and has a molecular weight of approximately 148 kilodaltons (kDa). Eculizumab was approved by the US Food and Drug Administration (FDA) in March 2007 for the treatment of PNH, Eculizumab has exclusivity rights until 2017, which protects it from competition until 2017. When the FDA approved it in September 2011 for the treatment of aHUS, it designated it as an orphan drug. The 2011 FDA approval was based on two small prospective trials of 17 people and 20 people

With Regards,
Nancy Ella
Managing Editor
Drug Designing: Open Access