Amitriptyline and nortriptyline response profiles in unipolar depressed patients

The relationship between steady-state plasma concentration and clinical response was studied in 22 hospitalized unipolar depressed patients. In a double-blind format the patients were randomly assigned to receive amitroptyline or nortriptyline. Dosage was adjusted based on plasma level with the aim of achieving a concentration of 60-180 ng/ml. By week 4 of treatment, 83% of amitriptyline patients and all nortriptyline patients were within the targeted plasma range. Based on final ratings of clinical state, the drug level adjustment improved the outcome for nortriptyline-treated patients, but not amitriptyline-treated patients. Nortriptyline patients with plasma levels of 60-230 mg/ml had lower Hamilton Rating Scale depression scores than patients outside that range. By contrast, amitriptyline plasma levels were not associated with depression ratings. After 1 week, patients treated with nortriptyline had a significantly greater mean reduction in Hamilton depression score, i.e., 55% compared to 25% for amitriptyline patients.