Pilot study of flesinoxan in major depression. Effect on REM latency and body temperature

Flesinoxan is a highly potent and selective 5‐HT1A full agonist, active in several models of depression. In this pilot open study, flesinoxan (4 mg/d) was administered orally for 4 weeks in 16 major depressive, mostly treatment‐resistant inpatients exhibiting a score of at least 19 on the Hamilton depression sale. Weekly ratings included Hamilton depression scale, Montgomery and Asberg depression scale (MADRS), and Clinical Global Impressions (CGI). Results showed considerable improvement in depressive symptomatology with mean MADRS scores (SD) dropping from 35.7 (10–40) to 13.0 (11.9) and CGI‐illness severity from 5.69 (1.14) to 2.73 (1.62) after 4 weeks of treatment. Moreover, 13 patients were classified as much or very much improved on the CGI‐global improvement. The tolerance of flesinoxan was excellent, with only four patients exhibiting side‐effects. In contrast to acute studies with 5HT1A agonists, flesinoxan induced no significant decrease in daily oral temperature over the 4‐week period. In eight melancholic patients, the mean REM latency (SD) of respectively 35.6 (15.9) and 40.2 (17.9) min during two baseline nights significantly increased to 51.9 (20.9) min during a double‐blind challenge night with flesinoxan 1 mg as compared to 42.0 (16.1) min with placebo, and to respectively 55.6 (29.9) and 55.6 (30.2) min during the last two treatment nights. All these findings encourage further developments of flesinoxan as a promising antidepressant.