Use of naloxone in the assessment of opiate dependence

All subjects participating in an outpatient study comparing treatments for opiate dependence were given a naloxone challenge to document their level of dependence. Subjects were assessed at 0, 10, 20, and 30 minutes following the administration of intramuscular naloxone (0.4 mg) using an opiate withdrawal assessment scale and measurements of pupillary diameter. Subjects' self reports of daily dollar amounts of opiate use and time since last use were also examined for possible correlation with withdrawal scale scores and pupillary measurements. A significant negative correlation was obtained between pupil diameter and time since last reported use of an opiate. Results indicated that the scale was a reliable indicator of opiate dependence. Ways in which it might be improved are discussed.