Tricyclic antidepressants: plasma levels and clinical findings in overdose.
Following amitriptyline or imipramine overdose by 30 patients, total plasma concentrations ranged from 29 to 1732 ng/ml but did not correlate well with physical findings or most electrocardiographic changes. Only those patients with a QRS interval greater than 0.1 second had significantly elevated plasma levels. However, a plasma level ratio of the parent drug (amitriptyline, imipramine) to its respective N-desmethyl metabolite (nortriptyline, desmethylimipramine) greater than or equal to 2.0 was associated with an acute overdose. This ratio was more useful than total plasma levels in differentiating an overdose from a therapeutic dose with associated toxicity and an elevated steady-state plasma level.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000639:Amitriptyline / Q000097:blood / Q000506:poisoning; D000929:Antidepressive Agents, Tricyclic / Q000097:blood / Q000506:poisoning*; D003891:Desipramine / Q000097:blood; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007099:Imipramine / Q000097:blood / Q000506:poisoning; D008297:Male; D008875:Middle Aged; D009661:Nortriptyline / Q000097:blood
D000929:Antidepressive Agents, Tricyclic; D000639:Amitriptyline; D009661:Nortriptyline; D007099:Imipramine; D003891:Desipramine