Effect of fenfluramine oral administration on serum prolactin levels in healthy and hyperprolactinemic women.

The effects of two different doses (40 and 80 mg orally) of fenfluramine on serum prolactin (PRL) levels have been evaluated in healthy and hyperprolactinemic women and compared with those of the potent dopamine antagonist sulpiride (100 mg i.m.). The lower fenfluramine dose resulted in a significant PRL rise in healthy women (n = 16) but not in hyperprolactinemics (n = 14). A dose-response effect was shown between 40 and 80 mg in control subjects (n = 7); in 4 hyperprolactinemics the higher dose also failed to increase PRL levels. Sulpiride resulted in a much greater PRL response. Since fenfluramine at the low doses used does not seem to exert antidopaminergic action, it is suggested that the mild PRL stimulation observed be mediated by the known brain serotoninergic activation induced by the drug.