Premium
Pain as a factor in the development of tolerance to morphine analgesia in man
Author(s) -
Ferguson Roger K.,
Mitchell C. L.
Publication year - 1969
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1969103372
Subject(s) - morphine , medicine , analgesic , tourniquet , anesthesia , saline , pain tolerance , drug tolerance , threshold of pain , pharmacology
An experiment was designed to test the hypothesis that pain is a factor in the development of tolerance to the analgesic effect of morphine in man. Pain was induced by the submaximum‐effort tourniquet technique. Four pain ratings were recorded: mild, moderate, severe, and unbearable. Subjects were randomly divided into two major groups: (1) those tested by the tourniquet technique each day and (2) those not tested until the final day. Each major group was randomly divided into two subgroups: (1) those receiving only morphine and (2) those receiving saline for 4 days and morphine on the final day. Morphine or saline was given intravenously. The purpose of the experiment was to compare the degree of tolerance development to chronically administered morphine in the tested versus nontested groups. In the subgroups receiving morphine, analgesia was significantly less in the tested than in the nontested group at the highest pain level. Moreover, in the morphine subgroup of the tested subjects, the degree of tolerance development was proportional to the severity of pain. These findings indicate that pain can augment the development of tolerance to the analgesic effect of morphine in man.