Characterization of the sigma ligand panamesine, a potential antipsychotic, by immune response in patients with schizophrenia and by sleep-EEG changes in normal controls

Panamesine (PAN) is a nearly specific sigma ligand. Recently, we showed tha t PAN in doses up to 90 mg/day improved psychometric variables in patients with an acute episode of schizophrenia. No side effects connected to the ex trapyramidal motoric system occurred; there was even an absence of daytime sedation. We investigated the effects of PAN on plasma cytokine and soluble cytokine receptor levels and blood cell counts during 4 weeks in ten patie nts out of the previous study sample. Under PAN treatment, tumor necrosis f actor (TNF)-alpha, soluble TNF receptors p55 and p75, and soluble interleuk in-2 receptor levels were not increased and neither were monocyte and lymph ocyte counts affected. This absence of immunomodulation is in contrast to c lozapine, but similar to haloperidol treatment. In a second study, a single dose of PAN (30 mg) or placebo was administered at 2200 hours to ten young male controls in order to investigate changes in the sleep EEG under the s ubstance. Sleep efficiency index increased, whereas time spent awake decrea sed. No significant changes in rapid eye movement (REM) sleep or non-REM pa rameters occurred. The sleep-EEG investigation showed sleep-consolidating e ffects of the drug, comparable to those of classical neuroleptics. Our resu lts support the hypothesis that the sigma ligand PAN, which has antipsychot ic properties, shares biological aspects with haloperidol.