Nonsteroidal cardiotonics. 3. New 4,5-dihydro-6-(1H-indol-5-yl)pyridazin-3(2H)-ones and related compounds with positive inotropic activities.
A series of substituted indolyldihydropyridazinones and related compounds 1-18 were synthesized and evaluated for positive inotropic activity. In rats, most of these indole derivatives produced a dose-related increase in myocardial contractility with little effect on heart rate and blood pressure. Compound 13, 4,5-dihydro-5-methyl-6-(2-pyridin-4-yl-1H-indol-5-yl)pyrazin-3(2H) -one (BM 50.0430), was further investigated in cats. The increase in contractility in this animal model was not mediated via stimulation of beta-adrenergic receptors. After oral administration of 1 mg/kg to conscious dogs, compound 13 and pimobendan were still active after 6.5 h. However, the cardiotonic effect of 13 was at least 2-fold that of pimobendan after this period of time. The structural requirements necessary for optimal cardiotonic activity within this novel class of indole derivatives are a heterocyclic aromatic ring in position 2, a hydrogen or a methyl group in position 3, and a dihydropyridazinone ring system in position 5 of the indole.
Department of Chemistry, Boehringer Mannheim GmbH, Mannheim, West Germany.
A
A
Mertens
W G
WG
Friebe
B
B
Müller-Beckmann
W
W
Kampe
L
L
Kling
W
W
von der Saal
D000818:Animals; D002316:Cardiotonic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002415:Cats; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D020105:Milrinone; D015394:Molecular Structure; D009200:Myocardial Contraction / Q000187:drug effects*; D011724:Pyridazines / Q000494:pharmacology; D011728:Pyridones / Q000494:pharmacology; D051381:Rats; D013329:Structure-Activity Relationship; D013997:Time Factors
D002316:Cardiotonic Agents; D011724:Pyridazines; D011728:Pyridones; C041648:pimobendan; D020105:Milrinone