Comparative study of the action of naloxone (Narcan) and nalorphine in man

The comparative study of 2 narcotic antagonists, naloxone and nalorphine, was performed in healthy volunteers. The influence of these drugs on the respiratory and cicularoty systems and on the psychical state was compared. The study was carried out in a double-blind, cross-over manner. Increasing doses of naloxone and placebo or nalorphine and placebo, were administered intravenously. Naloxone, even in very high doses, caused no changes in cardivascular system, acid-base balance, sensitivity of respiratory centre to carbon dioxide and psychical state of volunteers. After the administration of nalorphine, even in very small doses, changes in psychical state in all examined subjects were observed. Nalorphine caused the significant change in the ventilatory response to CO2. Based on their results, the authors conclude that naloxone has no agonist or intrinsic narcotic activity, as opposed to nalorphine possessing strong narcotic action.