The Joint Task Force concluded that 39,510 patients received Xolair (omalizumab) between 2003 and 2005. From this group, 35 patients had 41 episodes of anaphylaxis related to Xolair. Calculated anaphylaxis-reporting rate was 0.09% of patients, 61% of reactions occurred in the first 2 hours after one of the first 3 doses. Omalizumab binds to Cε3 region of IgE.
An observation period of 2 hours for the first 3 injections and 30 minutes for subsequent injections would have captured 75% of the anaphylactic reactions.
Click here for a case report of a delayed allergic reactions to omalizumab.
American Academy of Allergy, Asthma & Immunology/American College of Allergy, Asthma and Immunology Joint Task Force Report on omalizumab-associated anaphylaxis. Cox L, Platts-Mills TA, Finegold I, Schwartz LB, Simons FE, Wallace DV. J Allergy Clin Immunol. 2007 Dec;120(6):1373-7. Epub 2007 Nov 9.
Delayed allergic reactions to omalizumab: Are patients reporting all cases? JACI, 03/2008.
Image source: Wikipedia, public domain.
Images: Mechanisms of action of omalizumab. JACI, 02/2008.