Capsaicin is the primary active component of the heat and pain-eliciting lipid soluble fraction of the Capsicum pepper.1 Capsaicin signals are transduced by a heat-activated ion channel, the vanilloid receptor 1 (VR1), or transient receptor potential vanilloid 1 (TRPV1).2 CAY10448 is an iodinated nonivamide, a potent capsaicin receptor antagonist with an IC50 value of approximately 10 nM.3