Letter: Meperidine vs morphine.
D002908:Chronic Disease; D006801:Humans; D008614:Meperidine / Q000008:administration & dosage / Q000627:therapeutic use*; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use*; D010146:Pain / Q000188:drug therapy*
D009020:Morphine; D008614:Meperidine