PT  - JOURNAL ARTICLE
AU  - Butelman, E R
AU  - Winger, G
AU  - Zernig, G
AU  - Woods, J H
TI  - Butorphanol: characterization of agonist and antagonist effects in rhesus monkeys.
DP  - 1995 Feb 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 845--853
VI  - 272
IP  - 2
4099  - http://jpet.aspetjournals.org/content/272/2/845.short
4100  - http://jpet.aspetjournals.org/content/272/2/845.full
SO  - J Pharmacol Exp Ther1995 Feb 01; 272
AB  - The effects of butorphanol were studied in assays of antinociception, respiratory depression, sedation, diuresis and reinforcing effects in rhesus monkeys, and opioid binding in monkey brain. Butorphanol (0.003-0.1 mg/kg s.c.) was effective in the warm-water tail withdrawal assay in 50 degrees C water but not in 55 degrees C. Over a similar dose range, butorphanol caused substantial respiratory depression, without an obvious plateau. Constrained quadazocine apparent pA2 analysis on the respiratory depressant and antinociceptive effects of butorphanol yielded different values between the two assays (respiratory depression pA2 = 6.61; antinociception pA2 = 8.26). Butorphanol (0.1 mg/kg) antagonized the antinociceptive effects of etonitazene in 55 degrees C water, but caused a nonparallel leftward shift in the U50,488 dose-effect curve; both effects were probably due to butorphanol's intermediate efficacy at mu receptors. Butorphanol (0.0001-0.003 mg/kg per injection i.v.) was self-administered; unlike other mu opioid agonists, its maximum effect was depressed after pretreatment with quadazocine (0.01-1.0 mg/kg). Butorphanol (0.003-0.32 mg/kg) was devoid of substantial sedative or muscle relaxant effects, as measured by observational rating scales. Butorphanol (0.01-0.1 mg/kg s.c.), unlike U50,488 (0.01-0.32 mg/kg) did not cause diuresis. Kappa agonist or antagonist effects of butorphanol were not detected in the present studies. This profile is consistent with butorphanol's binding characteristics in rhesus monkey brain which indicated 12-fold mu:kappa selectively and 34-fold mu:delta selectivity.