Butorphanol precipitates abstinence in morphine dependent rats

Abstract

Butorphanol precipitated a withdrawal syndrome in rats receiving continuous intracerebroventricular infusions of morphine for three days. However, the potency of butorphanol to induce defecation, urination, teeth chattering and escape behavior was one to two orders of magnitude less on a molar basis than that of naloxone. Wet shake behavior, a prominent feature of naloxone precipitated withdrawal, was absent in morphine dependent animals challenged with butorphanol. These data indicate qualitative as well as quantitative differences in the withdrawal syndromes induced by butorphanol and naloxone.