title: Analgesic effects of dextromethorphan and morphine in patients with chronic pain.
abstract: N-methyl-aspartate (NMDA) receptor antagonists have been shown to improve opioid analgesia in the animal model. The cough suppressant dextromethorphan is a clinically available NMDA-receptor antagonist. In this randomised, double-blind, placebo-controlled study 20 patients with chronic pain of several years duration were given 100 mg of oral dextromethorphan or matching placebo 4 h prior to an intravenous infusion of morphine 15 mg. Pain intensity and adverse effects were assessed at 0, 4, 5 and 7 h. Dextromethorphan had no effect on morphine analgesia: the mean (+/-SEM) visual analogue scores for pain relief (VAS, 0-100 mm) at the end of the morphine infusion were 38 (+/-6) for dextromethorphan+morphine and 38 (+/-7) for placebo+morphine. VAS scores for pain intensity were comparable both at rest and at movement at all time points. The most common adverse effects reported were dizziness, nausea and sedation. There were no significant differences in either the incidence or severity of adverse effects. In conclusion, oral dextromethorphan 100 mg had no effect on pain relief by intravenous morphine 15 mg in patients with chronic pain.
authors.affiliation: Pain Clinic, Helsinki University Hospital, P.O. Box 340, 00029 HUS, Helsinki, Finland Department of Medical Sciences, Clinical Pharmacology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden The National Institute of Health, Mannerheimintie 166, 00300 Helsinki, Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Heiskanen
authors.forename: Brita
authors.initials: B
authors.lastname: Härtel
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Dahl
authors.forename: Timo
authors.initials: T
authors.lastname: Seppälä
authors.forename: Eija
authors.initials: E
authors.lastname: Kalso
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects; D002908:Chronic Disease; D003915:Dextromethorphan / Q000008:administration & dosage* / Q000009:adverse effects; D004311:Double-Blind Method; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D010146:Pain / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D018691:Excitatory Amino Acid Antagonists; D003915:Dextromethorphan; D009020:Morphine