biphalin and Weight-Loss

We compared the physical dependence liability of biphalin, a dimeric enkephalin analogue that possesses high antinociceptive activity, with that of morphine in equipotent intravenous doses. Naloxone challenge produced severe withdrawal signs after a 5-day infusion of morphine but only minor withdrawal signs after a 5-day biphalin infusion. In a cross-dependence study, biphalin did not suppress body weight loss after morphine withdrawal, but successfully suppressed weight loss after pentazocine withdrawal. These data support consideration of biphalin as a new analgesic with a novel pharmacological profile and minimum dependence liability.

Topics: Analgesics, Opioid; Animals; Behavior, Animal; Enkephalins; Infusions, Intravenous; Male; Morphine; Morphine Dependence; Naloxone; Pentazocine; Rats; Rats, Sprague-Dawley; Substance-Related Disorders; Weight Loss