['N-methyl-D-aspartate-receptor antagonists may be useful in pain management. The aim of this study was to evaluate dextromethorphan (DEX), a commonly used oral antitussive drug with NMDA-receptor antagonistic properties, in respect of its analgesic properties as single drug and co-administered with morphine (MO) on experimental ischemic pain. In addition, the analgesic effects of another clinically available NMDA-receptor antagonist, ketamine (KET) as well as of morphine (MO) were tested as active controls.', 'Nineteen healthy volunteers were included in the study. Experimental ischemic pain was induced using the forearm tourniquet test. Placebo (PLAC), oral DEX (30 and 90 mg, respectively), KET (9 microg kg(-1) min(-1) i.v.), MO (0.1 mg kg(-1), i.v.) and the DEX+MO and KET+MO combinations were evaluated during eight separate experiments. Development of ischemic pain was rated by visual analog scale (VAS) every minute over 30 min and ratings were summed as sum of pain scores (SPS).', 'DEX by itself did not influence SPS compared to PLAC. The DEX+MO co-administration did not enhance MO-induced analgesia. MO and KET reduced pain ratings by 27% and 39%, respectively. The KET+MO combination showed no enhancement of the analgesic effect in comparison with the respective drugs in monotherapy.'] Does the N-methyl-D-aspartate-receptor antagonist dextromethorphan lack analgesic effect in a human experimental ischemic pain model?