Ketazocine

Ketazocine, also known as ketocyclazocine, is a benzomorphan derivative used in opioid receptor research. Ketazocine, for which the receptor is named, is an exogenous opioid that binds to the κ opioid receptor.
Activation of this receptor is known to cause sleepiness, a decrease in pain sensation and dysphoria, paranoia, and hallucinations. It also causes an increase in urine production because it inhibits the release of vasopressin.
Unlike other opioids, substances that only bind to the κ receptor theoretically do not depress the respiratory system.
The crystal structure of ketazocine was determined in 1983.