Analgesic potencies of morphine 3- and 6-sulfates after intracerebroventricular administration in mice: relationship to structural characteristics defined by mass spectrometry and nuclear magnetic resonance.
Morphine 3-sulfate, which carries a polar, acidic group at the 3-position much like morphine, does not differ greatly in analgesic potency from morphine following intracerebroventricular administration. This differs from the non-ionizable 3-methyl and 3-ethyl ethers, which are less potent analgesics than morphine. Morphine 6-sulfate, which differs from morphine by having an ionizable group at carbon-6 at physiological pH, is a more potent analgesic than morphine following intracerebroventricular administration. Variations in analgesic potency following modifications at the hydroxyl groups appear only to reflect alterations in point charges rather than structural alterations.
D000700:Analgesics; D000818:Animals; D007276:Injections, Intraventricular; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D009020:Morphine / Q000008:administration & dosage*; D013329:Structure-Activity Relationship
D000700:Analgesics; D009020:Morphine