Biochem/physiol Actions Potent 5-HT2A serotonin receptor antagonist/inverse agonist that crosses the blood-brain barrier. Other Notes Tandem Mass Spectrometry data independently generated by Scripps Center for Metabolomics is available to view or download in PDF. R103.pdf Tested metabolites are featured on Scripps Center for Metabolomics METLIN Metabolite Database. To learn more, visit sigma.com/metlin.