title: Cardiovascular safety profile of MA-2029, a novel motilin receptor antagonist.
abstract: The aim of this study was to assess the cardiovascular effect of MA-2029, a selective motilin receptor antagonist highly expected for the treatment of irritable bowel syndrome (IBS). MA-2029 inhibited the human ether-a-go-go-related gene (hERG) current at 100 microg/ml, but shortened action potential duration (APD) in isolated guinea pig papillary muscles at 10 and 100 microg/ml and the corrected QT (QTc) interval after oral administration of 30 and 300 mg/kg in conscious telemetered dogs. The discrepancy was probably caused by blockade of the Ca(2+) channel because MA-2029 inhibited the Ca(2+) current in isolated guinea pig myocytes. MA-2029 at 100 microg/ml also decreased the maximum rising velocity and action potential amplitude in the action potential study, indicating that MA-2029 has Na(+) channel blocking potential. In the cardiovascular study, MA-2029 at 30 mg/kg induced slight cardiovascular changes such as hypotension, QTc shortening, and PR prolongation possibly caused by Ca(2+) channel blockade. The plasma concentration at 4 hr after 30 mg/kg administration was 2.10 microg/ml, 200-fold higher than the effective concentration of MA-2029 as a motilin receptor antagonist. These results suggest that MA-2029 has sufficient cardiovascular safety although it inhibits multiple ion channels at supra-effective concentrations. On the other hand, cisapride, an effective IBS drug, showed clear hERG inhibition and APD prolongation at 100 ng/ml. Cisapride exhibited a narrow safety margin because it caused QT prolongation potential even at the therapeutic concentration. In conclusion, MA-2029 is a novel drug highly expected for the treatment of IBS with lower cardiovascular risk than cisapride.
authors.affiliation: Fuji Gotemba Research Laboratories, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka, Japan. tabomty@chugai-pharm.co.jp
authors.forename: Mitsuyasu
authors.initials: M
authors.lastname: Tabo
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Komatsu
authors.forename: Masaki
authors.initials: M
authors.lastname: Honda
authors.forename: Misae
authors.initials: M
authors.lastname: Itoh
authors.forename: Kazuya
authors.initials: K
authors.lastname: Kimura
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002460:Cell Line; D020117:Cisapride / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D004562:Electrocardiography; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D043183:Irritable Bowel Syndrome / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D009842:Oligopeptides / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011964:Receptors, Gastrointestinal Hormone / Q000037:antagonists & inhibitors*; D018013:Receptors, Neuropeptide / Q000037:antagonists & inhibitors*; D013686:Telemetry
chemical_list: C528741:MA-2029; D009842:Oligopeptides; D011964:Receptors, Gastrointestinal Hormone; D018013:Receptors, Neuropeptide; C050802:motilin receptor; D020117:Cisapride