title: Synthesis and pharmacological properties of a new hydrophilic and orally bioavailable 5-HT4 antagonist.
abstract: 5-HT4 receptor antagonists have been suggested to have clinical potential in treatment of atrial fibrillation, diarrhea-prone irritable bowel syndrome and urinary incontinence. Recently, the use of 5-HT4 antagonists has been suggested to have a therapeutic benefit in heart failure. Affinity for the hERG potassium ion channel and increased risk for prolonged QT intervals and arrhythmias has been observed for several 5-HT4 ligands. Serotonin may also have beneficial effects in the central nervous system (CNS) through stimulation of the 5-HT4 receptor, and reduced distribution of 5-HT4 antagonists to the CNS may therefore be an advantage. Replacing the amide and N-butyl side chain of the 5-HT4 receptor antagonist SB207266 with an ester and a benzyl dimethyl acetic acid group led to compound 9; a hydrophilic 5-HT4 antagonist with excellent receptor binding and low affinity for the hERG potassium ion channel. To increase oral bioavailability of carboxylic acid 9, two different prodrug approaches were applied. The tert-butyl prodrug 11 did not improve bioavailability, and LC-MS analysis revealed unmetabolized prodrug in the systemic circulation. The medoxomil ester prodrug 10 showed complete conversion and sufficient bioavailability of 9 to advance into further preclinical testing for treatment of heart failure.
authors.affiliation: Drug Discovery Laboratory AS, Oslo Innovation Center, N-0349 Oslo, Norway.
authors.forename: Bjarne
authors.initials: B
authors.lastname: Brudeli
authors.forename: Lise Román
authors.initials: LR
authors.lastname: Moltzau
authors.forename: Cam H T
authors.initials: CH
authors.lastname: Nguyen
authors.forename: Kjetil Wessel
authors.initials: KW
authors.lastname: Andressen
authors.forename: Nils Olav
authors.initials: NO
authors.lastname: Nilsen
authors.forename: Finn Olav
authors.initials: FO
authors.lastname: Levy
authors.forename: Jo
authors.initials: J
authors.lastname: Klaveness
mesh_terms: D000284:Administration, Oral; D000818:Animals; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008297:Male; D015394:Molecular Structure; D051381:Rats; D017207:Rats, Sprague-Dawley; D044422:Receptors, Serotonin, 5-HT4 / Q000378:metabolism*; D058832:Serotonin 5-HT4 Receptor Antagonists / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D058832:Serotonin 5-HT4 Receptor Antagonists; D044422:Receptors, Serotonin, 5-HT4