Classification of psychoactive drugs by visually evoked potentials in rabbits by means of multiple discriminant analysis. A possible way of predicting the clinical efficacy of new psychoactive drugs.

The influence of representatives of various groups of antipsychotic drugs on the visually evoked potential (EP) was investigated with the aid of a modified recording and evaluation technique for the rabbit EEG from cortical and subcortical structures. The starting point was the hypothesis that changes in the EP in animal experiments caused by representative members of these "substance groups" (neuroleptics with predominantly antipsychotic or predominantly sedative effect, and antidepressants with predominantly mood-brightening or predominantly sedative main components) make predictions of the clinical efficacy of "unknown" substances possible on the basis of clinical therapeutic principles of classification. Experiments were carried out with haloperidol and fluphenazine, chlorpromazine, amitriptyline and doxepin, and with imipramine and clomipramine, as representatives of these classes of substances. The hypothesis was checked by attempts to assign amitriptyline and chlorprothixene in varying dosage, haloperidol, benzperidol and mianserine to appropriate classes. As classification and assignment procedure we used stepwise multiple discriminant analysis (SWDA) according to our modification of the BMD 0 7 M Program. The purpose of the latter program, and its applicability to our studies, are described and discussed. It was found 1. that with EP data from animal experiments it is possible to classify various groups of psychoactive drugs on the basis of clinical therapeutic findings, using SWDA; 2. that assignment of "unknown" compounds can be based on this classification; 3. that hence with some caution predictions of the clinical effect of newly developed substances may be made on the basis of findings in animal experiments. The EP variables which contain most information for making up the separation formula and hence are of special importance, are investigated with respect to their possible neurophysiological evidential value, and their significance is discussed. It was found that the EP from the visual cortex are of particular significance for the separation of groups in the form presented here.