Peak plasma conc. Analgesia may occur as early as 15min. There is no evidence to suggest that demerol provides better analgesia than other opioids for any type of pain. Demerol is contraindicated if patient has taken MAOI in the last 14 days. May lower seizure threshold and increase normeperidine induced CNS toxicity.
Morphine lacks toxic metabolite and many of the drug interactions of demerol.
Respiratory depression like other opioids. Repeated large doses at short intervals can produce tremors, mydriasis, and eventually convulsions. CNS toxicity is related to rate of metabolism of meperidine to normeperidine. Or a serum ratio of normeperidine to meperidine with ratio greater than 1.0 increasing the possibility for seizures. Naloxone is contraindicated due to its action to remove the depressive effect of meperidine.