Correlations between Serum Ami‐ and Nortriptyline Concentrations and Psychomotor Performance

Abstract

Correlations of serum nortriptyline (NT) and amitriptyline (AT) levels with psychomotor performance choice reaction performance, eye‐hand coordination, and divided attention was studied in two experiments each with 20 healthy subjects. In the first experiment serum NT level was measured with an isotope derivative method after treatment for 14 days with NT. In the second trial plasma AT and NT concentrations were measured with gas‐chromatography after treatment for 14 days with AT. No linear correlations between the levels of the antidepressants and performance variables were found. Low levels of NT (< 50 ng/ml) tended to shorten reaction time, and intermediate levels (50‐80 ng/ml) to prolong it, when compared with the reaction times during placebo. The correlation between serum NT levels and the increase of the tyramine dose in the tyramine pressor test was not significant. A new assay method for AT and NT is presented.