A sensitive method to evaluate effects of analgesics in man.

In recent papers (8, 12, 13) it has been shown that the analysis of event related brain potentials has become a powerful tool in attempts to quantify pain experience in man. However, the following conditions have to be fulfilled when cerebral potentials are used to measure experimentally induced pain, as well as pain relief under pharmacological treatments: 1) randomization of stimulus intensities to minimize effects of habituation within and between sessions (3), 2) randomization of interstimulus intervals with a minimum distance of about 15 seconds to avoid overlapping effects, and 3) control of the power spectral density of brain activity immediately before the stimulus is applied. In searching for pain related cerebral potentials a principal component analysis was utilized. The grand mean of all evoked potentials (analysis period 500 ms) was built, and the brain potentials were decomposed into basic waveforms for the different experimental conditions (painful-nonpainful; different kinds of skin stimuli). Two components were found as correlates of the painfulness in a sample of 8 healthy untreated subjects (4). In order to demonstrate the usefulness and sensitivity of the here described methods to quantify analgesic effects in man, the opioide tilidine and the opiate antagonist naloxone were orally administered in different combinations. In detail, the 5 treatments: tilidine (100 mg), naloxone (32 mg), tilidine (100 mg) + naloxone (8 mg), tilidine (100 mg) + naloxone (32 mg), and placebo, were given double blind (3 replications of 5 X 5 Latin squares) in 15 healthy subjects, each participating in 5 sessions with exactly 3 days intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

RCT Entities:   Population Interventions Outcomes