Plasma nortriptyline and clinical response

The relationship of plasma nortriptyline levels to the clinical response of 80 depressed patients was studied. Plasma nortriptyline levels were estimated 4 weeks after commencing treatment. Percentage change in the Hamilton Depression Rating Scale was used to measure clinical response. There was no simple relationship between these two measures. Twelve of the 80 patients were studied further. Clinical response to variations of plasma nortriptyline levels was studied. Calculation of regression coefficients showed a positive relationship between clinical change and plasma nortriptyline levels in all. Comparison of the regression coefficients showed that they differed significantly among themselves and were not related to age or sex.