Effects of potent analgesic 3-(3-phenylethyl)-9(3-methoxy-9a-(rn-hydroxyphenyl)-3-azabicyclo [3,3,1]-nonane (P-7521) on electro-encephalography in rabbits

P-7521 is a potent analgesic derived from 3-azabicyclo [3,3,1]-nonanes. The investigation was carried out on the unanesthetized. non-curarized rabbits. After iv 0.8, 4.0 0r 450 Vg/kg. a predominatly synchronized EEG which was characterized by the appearance of high voltage 1-3 Hz waves was seen both in the cortical and deep leads. The integration value of 6 activity increased from about 29% to higher than 50% while that of e activity decreased. In the sensorimotor cortex the spindle waves were poorly organized and slowed down. The EEG activated reaction produced by phonic stimulus was abolished. In all EEG records of P-7521 the spikes or the electrographic seizure were not seen. All of these EEG changes were associated with behavioral tranquillization. stupor and immobility. After icv P-7521 4.0 or 45.0 vg/kg the EEG changes were similar to those after iv. The EEG and behavioral effects of P-7521 could be antagonized by naloxone. The EEG changes were accompanied by the respiratory depression and the heart rate descent.