Fluoxetine is a potent and selective inhibitor of neuronal serotonin (5-hydroxytryptamine) reuptake. Fluoxetine reduces food, energy and carbohydrate intake and increases resting energy expenditure, which may account for the moderate and transient bodyweight loss observed with its use. Glucose tolerance and/or hypoglycaemia in patients with type 2 diabetes mellitus improve with fluoxetine therapy. The ability of fluoxetine to inhibit cytochrome P450 (CYP) isoenzymes (CYP2D6, CYP2C and CYP3A4), is potentially important for patients with physical illness who may be taking multiple concomitant medications. Fluoxetine was more effective than placebo in 2 double-blind, randomised trials, and according to limited data appears to be equally effective compared with other SSRIs and tricyclic antidepressants (TCAs), in the treatment of depression in patients with HIV/AIDS. The efficacy of fluoxetine is also superior to that of placebo in the treatment of depression in patients with diabetes mellitus and stroke as shown in double-blind randomised trials, although its efficacy relative to that of nortriptyline in stroke is uncertain. Fluoxetine had similar efficacy to that of desipramine in patients with cancer, with improved Hamilton Depression Rating Scale and quality-of-life scores from baseline; however, the drug was not more effective than placebo in a double-blind randomised trial. Medically healthy individuals tolerate fluoxetine well. Like other SSRIs, fluoxetine lacks the anticholinergic, cardiovascular, sedative and weight-increasing properties of TCAs, and is safer in overdose than TCAs and monoamine oxidase inhibitors. Rates of sexual dysfunction and suicidal ideation with fluoxetine appear similar to those seen with other SSRIs.
Conclusion: Fluoxetine has shown superior efficacy compared with placebo in the treatment of depression in patients with HIV/AIDS, diabetes mellitus or stroke; however, it has not significantly improved depressive symptoms versus placebo in patients with cancer. The efficacy of fluoxetine appears similar to that of desipramine in patients with stroke, cancer or HIV, and is similar to that of sertraline or paroxetine in patients with HIV/AIDS; comparisons with nortriptyline give equivocal results. The potential for drug interactions with fluoxetine use should be carefully considered because most patients with comorbid physical illness will be receiving multiple comedications. Although fluoxetine has proved effective as an antidepressant in this population in several clinical trials, its drug interaction profile and long half-life are a potential limitation, and these properties should be carefully considered in relation to the status of each patient.