Levomoramide

Levomoramide is the inactive isomer of the opioid analgesic dextromoramide, invented by the chemist Paul Janssen in 1956. Unlike dextromoramide, which is a potent analgesic with high abuse potential, levomoramide is virtually without activity.

"Resolution reveals that the analgetic activity in this case resides almost entirely in the (+) isomer."