title: Synthesis and structure-activity relationships of a new series of antiarrhythmic agents: 4,4-disubstituted hexahydro-3H-pyrido[1,2-c]pyrimidin-3-ones and related compounds.
abstract: A series of 4,4-disubstituted tetrahydro- and 4,4-disubstituted hexahydro-3H-pyrido[1,2-c]pyrimidin-3-ones (4 and 5, respectively) were prepared from 2-aryl-2-(2-piperidinyl)-4-[N,N-bis (1-methylethyl)amino] butanamides (2). Individual racemates of the piperidinyl amides 2 were converted to pure racemic diaza bicyclic compounds that were evaluated for antiarrhythmic activity in the Harris dog model and anticholinergic activity in a muscarinic receptor binding assay. Selected compounds were subsequently evaluated for hemodynamic effects in anesthetized dogs where blood pressure depression and negative inotropic activity were assessed. Of this group, 4a (R = CH3) and 5a (R = CH3) showed the most favorable pharmacological profiles; the former compound was chosen for toxicity testing over the latter due to its lack of noncompetitive inhibition of acetylcholine-induced contractions of guinea pig ileum segments. Clinical evaluation is now under way.
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000188:drug therapy*; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D003864:Depression, Chemical; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D011725:Pyridines / Q000138:chemical synthesis / Q000494:pharmacology / Q000627:therapeutic use; D011744:Pyrimidinones / Q000138:chemical synthesis / Q000494:pharmacology / Q000627:therapeutic use*; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D051381:Rats; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D011725:Pyridines; D011744:Pyrimidinones; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate