GENERAL PHARMACOLOGY OF A NEW POTENT 5-HYDROXYTRYPTAMINE ANTAGONIST

The potential of the investigational 5-hydroxytryptamine (5HT 3 ) antagonist, LY277359, to alter cardiovascular, central nervous system (CNS), smooth muscle, and gastrointestinal functions at multiples of pharmacologically active doses, was examined to provide a profile of possible secondary pharmacological effects. In the anesthetized dog, significant cardiovascular effects were observed at doses, 100-1000 and 4-15 times those found to be pharmacologically active at 5HT 3 receptors in vivo in rats and dogs, respectively. These effects were limited to decreased heart rate (approximately 20%) at intravenous doses of 1.75 and 3.5 mg/kg and prolonged Q-T c intervals (approximately 20 to 50%) at doses of a 4.38 to 3.5 mg/kg