The synthesis of the isomeric series 6-chloro-7-sulfamoyl- and 7-chloro-6-sulfamoyl-1(2H)-phthalazinones (1 and 2) and 6-chloro-7-sulfamoyl- and 7-chloro-6-sulfamoyl-3,4-dihydo-1(2H)-phthalazinones (3 and 4), combining structural features characteristic to furosemide and hydralazine, is described, the mechanism of the formation of 1 and 2 is discussed, and their structure-activities relationships are studied. Preliminary screening in the rat shows that series 1 and 3 exhibit diuretic and saluretic activity similar to that of chlorothiazide with, however, Na+/K+ ratios more favorable than chlorothiazide and furosemide. The compounds of series 2 and 4 are practically inactive. All four series show initial antihypertensive activity lower than that of hydralazine. However, compounds 1a, 1c, and 4a show a higher activity at 8 and/or 24 h after administration and thus may offer a unique combination of a "loop" diuresis with direct long-acting peripheral vasodilating effects.
The synthesis of a new series of N,N'-disubstituted 6,7-diazabicyclo[3.2.2]nonane derivatives is described. The antimuscarinic potency of these drugs was evaluated in the guinea pig ileum and compared to that of atropine sulfate. All the drugs tested competitively inhibited the acetylcholine-induced contractions. Kd values were calculated and, in several cases, compared to those obtained by direct binding to the muscarinic receptor from mouse brain. The order of potencies followed that which is known for various tropine and pseudotropine esters; that is, the 3alpha configuration is more potent than the 3beta configuration, and the quaternary analogues are more potent than the tertiary ones. The antimuscarinic activity of the drugs is dicussed in terms of their acetylcholine-like molecular arrangement that gives rise to a characteristic interaction pharmacophore.
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