Subjective, psychomotor, and physiological effects of cumulative doses of mixed-action opioids in healthy volunteers.
BACKGROUND
Conducting complete dose-response evaluations of multiple drugs in a single within-subjects experiment is very time-consuming when a complete session is required for evaluation of each dose.


OBJECTIVE
To evaluate a within-session cumulative-dosing procedure as a potentially efficient method for conducting dose-response evaluations of mixed-action opioids.


METHODS
Fifteen healthy volunteers received intravenous injections of saline, butorphanol, nalbuphine, pentazocine, or morphine in a randomized, double-blind, crossover design. Subjects received one injection per hour for the first 4 h, and a 3-h recovery period followed. Saline was injected first, then saline or increasing doses of each drug (except pentazocine, see below) were administered every hour for the next 3 h. The absolute doses per injection were morphine and nalbuphine 2.5, 5, and 10 mg/70 kg, butorphanol 0.5, 1, and 2 mg/70 kg, and pentazocine 7.5, 15, and 0 mg/70 kg. (The highest dose of pentazocine was omitted because of the risk of dysphoria and psychotomimesis). These injections resulted in cumulative doses of morphine or nalbuphine 2.5, 7.5, and 17.5 mg/70 kg, butorphanol 0.5, 1.5, and 3.5 mg/70 kg, and pentazocine 7.5 and 22.5 mg/70 kg. Mood, psychomotor performance, and vital signs were assessed.


RESULTS
Effects of all opioids were similar, with some exceptions. Butorphanol had the strongest effects on psychomotor performance and some subjective effects. Morphine was associated with delayed or prolonged side effects.


CONCLUSIONS
Orderly dose-response functions and replication of results of single-dosing studies confirmed that the cumulative-dosing procedure is an efficient way of determining dose-response functions for multiple opioids within the same subjects.
Walker
D J
DJ
University of Chicago, Department of Anesthesia and Critical Care, 5841 S. Maryland Avenue, MC 4028, Chicago, IL 60637, USA. dwalker@airway.uchicago.edu
Zacny
J P
JP
Galva
K E
KE
Lichtor
J L
JL
D000328:Adult; D003071:Cognition / Q000187:drug effects; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D009293:Opioid-Related Disorders / Q000523:psychology; D010101:Oxygen Consumption / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects*; D017450:Receptors, Opioid, mu / Q000819:agonists; D011795:Surveys and Questionnaires
D009294:Narcotics; D017450:Receptors, Opioid, mu; D009020:Morphine