Physiological effects of high dose naloxone administration to normal adults

The intravenous bolus administration of high doses of the opioid receptor antagonist naloxone (in the mg./kg. range) to normal adults produced dose-dependent increases in systolic blood pressure and respiratory rate. No significant alterations in other physiological processes were found although there were trends for increases in oral temperature and pulse rate with increasing dose. These results suggest the involvement of an endogenous opioid system in the tonic regulation of human systolic blood pressure and respiration and the probable inadequacy of doses of naloxone previously utilized in human studies to effect complete blockade of endogenous opioid systems.