Characterisation of [3H]-darifenacin as a novel radioligand for the study of muscarinic M3 receptors. 1997

C M Smith, and R M Wallis
Discovery Biology, Pfizer Central Research, Sandwich, Kent, England.

Darifenacin, (S)-2-[1-[2,3-dihydrobenzofuran-5-yl]-3- pyrrolidinyl]-2,2-diphenylacetamide, is a novel muscarinic M3 antagonist. In this study we have compared the binding of [3H]-darifenacin to the five cloned human muscarinic receptors (m1-m5) expressed in CHO cells. [3H]-darifenacin binds with 6 fold higher affinity to m3 (KD = 0.33 nmol/l) over m1 (KD = 1.6 nmol/l) receptors. There was no specific binding of [3H]-darifenacin to m2 receptors and specific binding to m4 and m5 receptors was insufficient to determine a KD. Binding of [3H]-darifenacin to m1 and m3 was displaced by atropine (m1 pKi = 9.36, m3 pKi = 9.4), 4-DAMP (m1 pKi = 9.04, m3 pKi = 9.19), pirenzepine (m1 pKi = 8.63, m3 pKi = 6.85), methoctramine (m1 pKi = 7.28, m3 pKi = 6.63), and darifenacin (m1 pKi = 8.36, m3 pKi = 9.14), demonstrating that [3H]-darifenacin represents the first selective m3 radioligand.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D010276 Parasympatholytics Agents that inhibit the actions of the parasympathetic nervous system. The major group of drugs used therapeutically for this purpose is the MUSCARINIC ANTAGONISTS. Antispasmodic,Antispasmodic Agent,Antispasmodic Drug,Antispasmodics,Parasympathetic-Blocking Agent,Parasympathetic-Blocking Agents,Parasympatholytic,Parasympatholytic Agent,Parasympatholytic Drug,Spasmolytic,Spasmolytics,Antispasmodic Agents,Antispasmodic Drugs,Antispasmodic Effect,Antispasmodic Effects,Parasympatholytic Agents,Parasympatholytic Drugs,Parasympatholytic Effect,Parasympatholytic Effects,Agent, Antispasmodic,Agent, Parasympathetic-Blocking,Agent, Parasympatholytic,Agents, Antispasmodic,Agents, Parasympathetic-Blocking,Agents, Parasympatholytic,Drug, Antispasmodic,Drug, Parasympatholytic,Drugs, Antispasmodic,Drugs, Parasympatholytic,Effect, Antispasmodic,Effect, Parasympatholytic,Effects, Antispasmodic,Effects, Parasympatholytic,Parasympathetic Blocking Agent,Parasympathetic Blocking Agents
D010880 Piperidines A family of hexahydropyridines.
D010890 Pirenzepine An antimuscarinic agent that inhibits gastric secretion at lower doses than are required to affect gastrointestinal motility, salivary, central nervous system, cardiovascular, ocular, and urinary function. It promotes the healing of duodenal ulcers and due to its cytoprotective action is beneficial in the prevention of duodenal ulcer recurrence. It also potentiates the effect of other antiulcer agents such as CIMETIDINE and RANITIDINE. It is generally well tolerated by patients. Gastrotsepin,Gastrozepin,L-S 519,LS-519,Piren-Basan,Pirenzepin,Pirenzepin Von Ct,Pirenzepin-Ratiopharm,Pirenzepine Dihydrochloride,Pyrenzepine,Ulcoprotect,Ulgescum,Dihydrochloride, Pirenzepine,LS 519,LS519,Piren Basan,Pirenzepin Ratiopharm,Von Ct, Pirenzepin
D011759 Pyrrolidines Compounds also known as tetrahydropyridines with general molecular formula (CH2)4NH. Tetrahydropyridine,Tetrahydropyridines
D011976 Receptors, Muscarinic One of the two major classes of cholinergic receptors. Muscarinic receptors were originally defined by their preference for MUSCARINE over NICOTINE. There are several subtypes (usually M1, M2, M3....) that are characterized by their cellular actions, pharmacology, and molecular biology. Muscarinic Acetylcholine Receptors,Muscarinic Receptors,Muscarinic Acetylcholine Receptor,Muscarinic Receptor,Acetylcholine Receptor, Muscarinic,Acetylcholine Receptors, Muscarinic,Receptor, Muscarinic,Receptor, Muscarinic Acetylcholine,Receptors, Muscarinic Acetylcholine
D003959 Diamines Organic chemicals which have two amino groups in an aliphatic chain. Diamine
D006224 Cricetinae A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS. Cricetus,Hamsters,Hamster
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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