Description_x000D_ Packaging_x000D_ 5, 25 mg in glass bottle_x000D_ Biochem/physiol Actions_x000D_ PF-4455242 is a selective k opioid receptor (KOR) antagonist with 20-fold selectivity for kappa over mu receptors (k Ki = 3 nM, μ Ki =64 nM). PF-4455242 is orally active, has good brain penetration in rats and was able to block the effects of the kappa agonist U50488. Studies indicate that k blockade has afforded antidepressant activity in several animal models. PF-4455242 has been in phase I clinical trials for trial for bipolar depression._x000D_ Features and Benefits_x000D_ This compound is featured on the Opioid Receptors page of the Handbook of Receptor Classification and Signal Transduction. To browse other handbook pages, click here._x000D_ Other Notes_x000D_ This compound was developed by Pfizer for Neuroscience research. To learn more about Sigma′s partnership with Pfizer and view other authentic, high-quality Pfizer compounds, visit sigma.com/bsm-pfizer._x000D_ To browse the list of other pharma-developed compounds and Approved Drugs/Drug Candidates, click here._x000D_ Legal Information_x000D_ Sold for research purposes under agreement from Pfizer Inc._x000D_ Pfizer is a registered trademark of Pfizer, Inc.