Effect of Levallorphan Tartrate on Levorphanol Tartrate Analgesia in Postoperative Patients

After major thoracic surgery it is important to provide efficient analgesia without the hazard of respiratory despression. In 1952 Fromherz and Pellmont¹ suggested, on the basis of animal experiments, that there may exist a ratio at which the respiratory depression induced by levorphan tartrate (Levo-Dromoran Tartrate)* could be counteracted by levallorphan tartrate (Lorfan Tartrate)† without significant loss of analgesia. Support for this theory was provided by Gross and Hamilton.² In normal human volunteers they found that on simultaneous administration less levallorphan tartrate was required to prevent respiratory depression than was necessary to affect the analgesia produced by levorphan tartrate. Cullen and Santos³ reported favorably on a combination of 10 parts of levorphan tartrate and 1 part of levallorphan tartrate in patients with chronic pain. The present study represents an attempt to evaluate this combination in patients after major thoracic surgery. The aim of the study was to