Serum prolactin levels after buspirone in man.

The acute effects of buspirone, an anxiolytic with mixed dopamine (DA) agonist-antagonist properties (achieved by blocking pre- and postsynaptic receptors) on serum prolactin (PRL) were studied in cross-over and double-blind trials in ten healthy young males. Sulpiride (200 mg) was used as a control drug; it raised PRL by almost 800%. Buspirone (25, 50 and 100 mg) raised serum PRL dose-dependently; the greatest increases (30, 70, and 320% from baseline, respectively) were seen 1 h after each dose. The results suggest that buspirone blocks postsynaptic DA receptors only at doses higher than those needed for anxiolysis.