The electrocardiographic and antiarrhythmic effects of imipramine hydrochloride at therapeutic plasma concentrations.
The electrocardiographic effects of imipramine hydrochloride at therapeutic plasma concentrations were determined in 44 depressed patients during a 6-week clinical outcome study of depression. During each week of the protocol, i.e., 2 weeks of control and 4 weeks of drug treatment, a standard 12-lead ECG, high-speed, high-fidelity ECG tracings, and a 24-hour continuous ECG recording were obtained. PR, QRS, and QTc intervals, T-wave amplitude, heart rate and frequency of ventricular premature depolarizations (VPDs) were measured. The plasma concentration of imipramine and desmethylimipramine was measured three times a week. Imipramine prolonged the PR (p less than 0.001), QRS (p less than 0.001) and QTc (p less than 0.001) intervals, increased the heart rate (p less than 0.001) and lowered T-wave amplitude (p less than 0.05) during the 4 weeks of treatment. No patient developed high-grade atrioventricular block or severe intraventricular conduction abnormalities. In addition, imipramine had a potent antiarrhythmic action in patients who were recovering from depression. Ten of 11 patients who had more than 10 VPDs/hour had 90% or greater arrhythmia suppression during antidepressant treatment with imipramine at plasma concentrations ranging from 100--302 ng/ml.
D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D000929:Antidepressive Agents, Tricyclic / Q000009:adverse effects; D001145:Arrhythmias, Cardiac / Q000188:drug therapy; D002037:Bundle-Branch Block / Q000188:drug therapy; D003863:Depression / Q000188:drug therapy*; D003891:Desipramine / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007099:Imipramine / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D008875:Middle Aged
D000889:Anti-Arrhythmia Agents; D000929:Antidepressive Agents, Tricyclic; D007099:Imipramine; D003891:Desipramine