Amitriptyline plasma-concentration and clinical effect. A World Health Organisation Collaborative Study.
54 patients in five centres participated in a study of the relationship between steady-state plasma-levels of amitriptyline (AT) and its active metabolite nortriptyline (NT) and therapeutic response. The participants were inpatients who, after a 7-12 day period of assessment, were rated greater than or equal to 16 on the Hamilton rating scale for depression. They were given 75 mg of amitriptyline for 3 days and then 150 mg daily for an active-treatment period of 6 weeks. Clinical ratings and plasma-samples were obtained at baseline then at 2, 4, and 6 weeks after starting therapy. Contrary to the findings of three previous trials, no important correlations were found between steady-state plasma-levels and therapeutic outcome or corrected side-effects. Corrected side-effects correlated negatively with therapeutic outcome. There seems little advantage in routine monitoring of AT and NT, since variations in plasma-levels do not account for the considerable variation in therapeutic outcome.
D000328:Adult; D000368:Aged; D000639:Amitriptyline / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D003718:Denmark; D003863:Depression / Q000188:drug therapy*; D004341:Drug Evaluation; D004739:England; D005260:Female; D005500:Follow-Up Studies; D005860:Germany, West; D006801:Humans; D007391:International Cooperation; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D009661:Nortriptyline / Q000097:blood; D013997:Time Factors; D014586:USSR; D014944:World Health Organization
D000639:Amitriptyline; D009661:Nortriptyline