Taloximine, a new respiratory stimulant with brochodilator properties.

1. A novel phthalazine analogue taloximine (1-hydroxyimino-4(2-dimethyl-aminoethoxy)-1,2-dihydrophthalazine monohydrochloride monohydrate) stimulated respiration in conscious rabbits at doses of 7 mg/kg and above.2. Taloximine antagonized the depressant action of morphine on respiration in rabbits at doses of 10 mg/kg. At high doses it resuscitated rabbits after they had been given lethal doses of sodium pentobarbitone.3. In in vitro preparations of the trachea or bronchus taloximine was about equiactive with aminophylline. In the Konzett-Rössler preparation the intravenous ED50 for taloximine was about 18% of that of aminophylline, whereas after oral administration the two drugs were equiactive.4. Taloximine, unlike aminophylline, did not protect guinea-pigs against anaphylactic microshock to egg albumen.5. Taloximine shortened the duration of the loss of righting reflex in mice due to hexobarbitone more effectively than bemegride, nikethamide or vanillic acid diethylamide.6. In the dose required to stimulate respiration taloximine had only slight cardiovascular effects. Up to four times this dose produced no evidence of general excitation of the central nervous system.