Allergy medicines' mechanism: Do they bind IgE or mast cells?

[Roger Chi-Che Lee]

Does anyone know about any studies about how common OTC allergy medicines  
work?  I'm interested in assaying various drugs for their binding affinity  
to IgE.  I would appreciate any info about the drugs mechanism or just any  
info related to assaying OTC allergy medicines' efficacy.  Thanks.