zimeldine and Pain--Intractable

In patients suffering from chronic pain, visual evoked potentials (VEP) and pain measures (PM) were investigated before and after a 4-week, double-blind controlled study of a new, rather selective, serotonin-reuptake inhibitor, Zimelidine, versus placebo. Before the trial most of the patients showed an augmenter response in VEP which means that the maximum amplitude of the evoked potential increased when stimulus intensity increased. After treatment most of the patients in the Zimelidine group revealed a reducer response, i.e. the maximum amplitude of the evoked potential decreased despite the increase of stimulus intensity, while no significant changes occurred in the placebo group. Only small and mostly insignificant changes were noted in PM. The results indicate that the augmenter-reducer response in VEP may be a useful measurement for following changes in the serotoninergic pathways in CNS. The results also indicate that treatment with Zimelidine may result in a decreased sensitivity to noxious stimulation that should be reflected in relief of clinical pain syndromes.

Topics: Adult; Aged; Brompheniramine; Evoked Potentials; Female; Humans; Male; Middle Aged; Neural Pathways; Pain, Intractable; Photic Stimulation; Pyridines; Sensory Thresholds; Serotonin; Zimeldine

Before a double-blind controlled study of zimelidine, a new, rather specific inhibitor of serotonin uptake, in patients with chronic pain, visual evoked potentials (EPs) to stimuli of varying intensities were recorded. During the trial the blood levels of zimelidine and its active metabolite norzimelidine were estimated. Side effects were rated by a physician before and after the trial. No significant difference in frequency of side effects could be found between the zimelidine and the placebo groups. Furthermore, there was no significant relationship between the blood levels of the active drug or its metabolite and the frequency of side effects. Instead, a significant relationship was found in the total group between the frequency of side effects and the tendency to react with an increase in maximum amplitude of the EP when stimulus intensity was increased (i.e., augmenting). The same trend was clear both in the zimelidine group and in the placebo group. Thus the augmenting/reducing response in visual EPs seems to be a predictor of the side effects reported irrespective of the drugs given.

Topics: Adult; Aged; Brompheniramine; Double-Blind Method; Evoked Potentials; Female; Humans; Male; Middle Aged; Pain, Intractable; Photic Stimulation; Pyridines; Serotonin Antagonists; Visual Perception; Zimeldine

Both the endorphin and the serotonin systems seem to be involved in pain perception, and a significant positive correlation between the levels of endorphins and 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF) has been established. In the present study, 20 chronic pain patients were treated with zimelidine, a rather selective inhibitor of serotonin reuptake, or placebo. Zimelidine produced a significant pain relief and a significant reduction of the levels of endorphins and 5-HIAA in CSF, while no significant changes occurred during placebo treatment. The results indicate that both the endorphin and the serotonin systems are involved in pain perception and that the systems are functionally related.

Topics: Adult; Brompheniramine; Double-Blind Method; Endorphins; Female; Humans; Hydroxyindoleacetic Acid; Male; Middle Aged; Pain, Intractable; Pyridines; Zimeldine