<qa>  What was the name of the maleic acid salt of Org 4420?The maleic acid salt of Org 4420, code name Org 50081 esmirtazapine, was selected for development in the treatment of insomnia. The first clinical trial with esmirtazapine was a proof-of-concept trial with a four-way cross-over design. All 3 esmirtazapine dose groups showed a statistically significant positive effect on TST objective and subjective and Wake Time After Sleep Onset WASO, as compared to placebo. 