Effects of ipsapirone in healthy subjects: a dose-response study

A dose-response study of ipsapirone (IPS), a 5HT_1a partial agonist, was conducted in healthy male subjects. IPS was administered in doses of 5,10 and 20 mg PO in a placebo-controlled, double-blind design to 15 subjects on 4 test days separated by at least 3 days. Oral temperature, ACTH, cortisol, prolactin, blood pressure, pulse rate and behavioral variables were assessed every 30 min for 3 h after administration of tablets (at 10:00 a.m.). IPS at 20 mg significantly decreased temperature and increased cortisol levels. Although IPS increased ACTH levels at 20 mg, this effect was variable and not significant. IPS did not affect prolactin levels nor did it have any behavioral effects. Although 20 mg IPS decreased blood pressure and pulse rate in one subject, overall it had no significant effect on these parameters. IPS at 20 mg PO appears a useful probe to test 5HT_1a function when temperature and cortisol are used as response variables. These results replicate earlier studies on the effect of IPS in healthy human subjects.