A Canadian multicenter study of three fixed doses of controlled-release ipsapirone in outpatients with moderate to severe major depression.

Ipsapirone, an azapirone with 5-hydroxytryptamine (5-HT1A) partial agonist activity, has been shown in preliminary studies to be effective in the treatment of major depressive disorder. This 8-week, randomized, double-blind study compared the efficacy, safety, and tolerability of three fixed doses of controlled-release ipsapirone (10-, 30-, and 50-mg dose once daily) with placebo in 410 patients with moderate to severe major depression (Hamilton Rating Scale for Depression [HAM-D] score > or = 20). The 10-mg ipsapirone treatment arm was discontinued early in the study. A total of 390 patients were eligible for evaluation in the intent-to-treat sample. The primary efficacy variable was the change in HAM-D total score from baseline to visit 8. There was no significant difference in efficacy in the two treatment groups versus the placebo group. The overall treatment response, defined as a 50% decrease in the HAM-D total score from baseline, was 43% with ipsapirone 50 mg given once daily, 34% with ipsapirone 30 mg given once daily, and 35% with placebo. In subanalyses, ipsapirone 50 mg given once daily was superior to placebo according to the HAM-D Core Depression (mood, guilt, interest, psychomotor activity) subtotal (p = 0.0453) and Melancholic item (p = 0.0225). Ipsapirone 30 mg given once daily was superior to placebo only in patients with moderate depression (baseline HAM-D total score < or = 25; p = 0.0100). The most common adverse effect in all groups was headache. The only dose-dependent adverse effects were dizziness and nausea.