All the major classes of antidepressant drug have been evaluated, including tricyclic antidepressants, monoamine oxidase inhibitors, selective serotonin uptake inhibitors, and atypical antidepressants. The findings have been relatively consistent and may be summarized as follows (adapted from Wilson and Fairburn (57)).
1. Antidepressant drugs are more effective than placebo at reducing the frequency of binge eating and purging. On average, among treatment completers there is about a 60 per cent reduction in the frequency of binge eating and a cessation rate of about 20 per cent. The therapeutic effect is more rapid than that seen in depression. There is generally little change in the placebo group. The drop-out rate varies but averages about 30 per cent.
2. The longer-term effects of antidepressant drugs remain largely untested. Almost all of the studies to date have been of their short-term use (16 weeks or less). The findings of the few longer-term studies suggest that outcome is poor whether or not patients remain on medication.
3. Few studies have evaluated the effects of antidepressant drugs on features other than binge eating and purging. Mood improves as the frequency of binge eating declines but this effect is common to all treatments for bulimia nervosa. Antidepressant drugs do not appear to modify the patient's extreme dieting which may account for the apparently poor maintenance of change.
4. The different antidepressant drugs seem to be equally effective, although there have been no direct comparisons of different drugs.
5. With one exception, there have been no systematic dose-response studies. The exception showed that fluoxetine at a dose of 60mg/day, but not 20mg/day, was more effective than placebo.
6. Patients who fail to respond to one antidepressant drug may respond to another. There have been no drug augmentation studies.
7. No consistent predictors of response have been identified. Pretreatment levels of depression appear not to be related to outcome.
8. The mechanism(s) whereby antidepressant drugs exert their 'antibulimic' effects is not known. The apparent comparability of different classes of drug implicates a common mechanism but this is unlikely to be their antidepressant action since the response is too rapid and the level of depression does not predict outcome.
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