Omalizumab is prescribed for a patient with severe allergic asthma inadequately controlled on high-dose inhaled corticosteroids. Before calculating the dosing regimen, which two parameters must be measured?
- A Specific allergen panel and skin prick reactivity
- B FEV1 percent predicted and eosinophil count
- C Body weight and baseline total serum IgE ✓
- D Blood group and complement C3 level
Correct answer: C. Body weight and baseline total serum IgE
Explanation
Omalizumab is an anti-IgE monoclonal antibody that binds free circulating IgE at the A epsilon 3 domain, preventing its attachment to Fc epsilon RI on mast cells and basophils. Dosing charts are constructed from the patient's body weight and baseline total serum IgE, because the antibody dose must be sufficient to bind the circulating IgE load. Eosinophil counts guide anti-IL-5 biologics such as mepolizumab, not omalizumab.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.