or combinations of any of the foregoing the sedatives include the barbiturate sedatives such as amobarbital aprobarbital butabarbital butabital mephobarbital metharbital methohexital pentobarbital phenobartital secobarbital talbutal theamylal thiopental and their pharmaceutically acceptable salts and the nonbarbiturate sedatives include benzodiazepines having a sedative action such as chlordiazepoxide clorazepate diazepam flurazepam lorazepam oxazepam temazepam triazolam and their pharmaceutically acceptable salts h 1 antagonists having a sedative action such as diphenhydramine pyrilamine promethazine chlorpheniramine chlorcyclizine and their pharmaceutically acceptable salts neuroleptics such as droperidol and miscellaneous sedatives such as glutethimide meprobamate methaqualone dichloralphenazone and their pharmaceutically acceptable salts skeletal muscle relaxants include baclofen carisoprodol chlorzoxazone cyclobenzaprine methocarbamol orphrenadine and their pharmaceutically acceptable salts the third component of the drug composition of this invention is a nontoxic nmda receptor antagonist among the nontoxic substances that block the nmda receptor and as such are useful for enhancing the analgesic activity of the combination therapeutic in accordance with this invention are dextromethorphan 3 hydroxy n methylmorphinan and its metabolite dextrorphan 3 hydroxy n methylmorphinan their mixtures and their pharmaceutically acceptable salts other useful nontoxic substances that block the nmda receptor include ketamine memantine pyrroloquinoline quinone and cis 4 phosphonomethyl 2 piperidinecarboxylic acid of the nmda receptor antagonists dextromethorphan is preferred for use herein due to its high degree of proven safety and its ready availability as the hydrobromide salt while dextrorphan.