Acute effects of zimelidine and alaproclate, two inhibitors of serotonin uptake, on neuroendocrine function.

The accumulation of 14C-5-hydroxytryptamine in human platelets in vitro and plasma levels of a number of hypophyseal hormones and cortisol in healthy male volunteers were determined after acute oral administration of zimelidine and alaproclate, two selective inhibitors of serotonin (5-HT) uptake. Alaproclate (100 mg) significantly inhibited the accumulation of 14C-5-HT by 42% at 90 minutes but showed no significant effect at 4 hours. At 200 mg the decrease in the accumulation was 55% after 90 minutes and 31% after 4 hours. Zimelidine (200 mg) caused a 72% decrease at 90 minutes and 73% at 4 hours. Plasma levels of prolactin, growth hormone, luteinizing hormone, follicle stimulating hormone, and thyroid stimulating hormone remained unchanged after zimelidine and alaproclate, and the levels were comparable to those after placebo. A physiological decline of plasma cortisol levels was noted in the morning during the test period of 4 hours, but there were slight differences in the secretory pattern after the different drugs used.