Iprindole and Imipramine in Non-Psychotic Depressed Out-Patients

Abstract

A study conducted with 100 depressed and anxious-depressed clinic and general practice out-patients indicated iprindole to be similar in efficacy to imipramine, a standard tricyclic antidepressant. Iprindole was shown to produce fewer side effects, particularly of an autonomic nervous system and sedative nature, than imipramine. On the other hand, there was a higher attrition rate on iprindole than on imipramine. This differential attrition occurred only in general practice patients, but improvement analyses revealed no significant preference for either medication in the two populations. As has often been observed by us, general practice patients were shown by several criterion measures to improve more, irrespective of medication, than clinic patients. No differences in efficacy between the two drugs were noted as a function of diagnosis (depressed versus anxious-depressed) or initial level of depression. However, initial level of anxiety was found to have a marked effect on drug response. Highly significant drug x anxiety interaction effects indicated iprindole to be particularly effective in low anxious and especially ineffective in high anxious patients, while imipramine produced better response in high anxious than in low anxious patients. It is suggested that these findings might be related in part to the side effects of the two drugs. The most frequently reported side effect on iprindole was dizziness and weakness, which low anxious patients probably minded less than high anxious patients. Drowsiness, most commonly reported on imipramine, might well have been tolerated better by high anxious than by low anxious patients. Improvement analyses in general, and a repeated measurement analysis in particular, indicated both iprindole and imipramine to be relatively fast-acting, producing marked improvement during the first two weeks and more gradual improvement at later intervals. These data also demonstrated both agents to produce a high level of clinical improvement over the six-week study period, with symptoms reduced in most patients from moderate severity to mild or very mild intensity.