The degree of analgesia correlates to spinal morphine concentration after intrathecal administration in rats.
Antinociceptive effects of intrathecal injections of morphine and pethidine were evaluated in rats using the hot-plate and tail-flick tests. Both drugs elicited antinociceptive effects either it was evaluated with maximal response latency (sec.) or with area under the curve (AUC) (sec. X min.). The effects of pethidine were shortlived. The concentration of morphine in the spinal cord correlated to its antinociceptive effects when tested on hot plate. A minimal morphine concentration of 3 pmol/mg in the spinal cord was required to induce experimental analgesia in the rat.
D000698:Analgesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007278:Injections, Spinal; D008297:Male; D008614:Meperidine / Q000494:pharmacology; D009020:Morphine / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000032:analysis / Q000187:drug effects*
D009020:Morphine; D008614:Meperidine