The COX (ovine/human) Inhibitor Screening Assay directly measures PGF2α produced by SnCl2 reduction of COX-derived PGH2. The prostanoid product is quantified via ELISA using a broadly specific antibody that binds to all the major PG compounds. Thus, the Cayman COX Assay is more accurate and reliable than an assay based on peroxidase inhibition. Cayman’s COX Inhibitor Screening Assay includes both ovine COX-1 and human recombinant COX-2 enzymes in order to screen isozyme-specific inhibitors. This assay is an excellent tool which can be used for general inhibitor screening, or to eliminate false positive leads generated by less specific methods.