The (+) and (-) isomers of tifluadom were assessed in rats for their opioid activities. In vitro (+)-tifluadom was almost equipotent at μ- and κ- sites and about 10 times less potent at δ-sites: (-)-tifluadom had the same binding spectrum but was 10-20 times less potent. In vivo (+)-tifluadom delayed the hot-plate reaction time; this effect was antagonized by naloxone, but not by Ro 15-1788. (-)-Tifluadom up to 20 mg/kg had no antinociceptive effect. In the intestinal transit test analgesic doses of (+)-tifluadom did not delay the intestinal transit of a charcoal meal in rats and had weak antagonist activity against morphine-induced inhibition of intestinal transit, whereas (-)-tifluadom had neither agonist nor antagonist effect. It thus appears that (+)-and (-)-tifluadom are not selective in vitro and in vivo for one type of opioid binding site/receptor.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Neurology
- Cellular and Molecular Neuroscience