Smith Kline & French Laboratories Limited

Brian H Warrington

John C Emmett

Robert A Slater

William J Coates

Hunter Douglas Prain

The invention relates to pyridazinone derivatives which have inotropic, vasodilator and bronchodilator activity. The compounds of the invention are described by formula (I): ##STR1## wherein: R.sup.1 is hydrogen or methyl;

Benzene compounds having two pyridazinone substituents

This invention relates to tricyclic pyridazinone compounds, pharmaceutical compositions containing the compounds, and a method of stimulating cardiac activity in a mammal by administering an effective amount of the compound. A compound of the invention is 7-carboxamido-4,4a-dihydro-4a-methyl-[5H]-indeno[1,2-c]-pyridazin-3[2H]-on e.

Tricyclic pyridazinone compounds

This invention relates to 5-(phenyl)-2(1H)-pyrazinones substituted in the 4-position of the phenyl ring by an amino or acylamino group. These compounds has inotropic activity. One specific compound is 5-(4-acetamidophenyl)-2(1H)-pyrazinone.

Heterocyclic compounds having inotropic activity

This invention relates to 5-(phenyl)-2(1H)-pyrazinones substituted in the 4-position of the phenyl ring by an amino or acylamino group. These compounds have inotropic activity. One specific compound is 5-(4-acetamidophenyl)-2(1H)-pyrazinone.

5-(4-Amino or acylaminophenyl)-2(1H)-pyrazinones having inotropic

A process for preparing 6-(2-hydroxyphenyl)-3-pyridazinone which comprises reacting 2-hydroxyacetophenone with glyoxylic acid under alkaline conditions, adjusting the pH of the reaction mixture to give a mixture within a pH range of about pH 4.0-9.5 and which contains a weak base, and subsequently reacting with hydrazine. 6-(2-Hydroxyphenyl)-3-pyridazinone is a useful intermediate in the preparation of anti-hypertensive agents.

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Welwyn Garden City, United Kingdom

Brian H Warrington