Mixed dextropropoxyphene poisoning: concentration-effect relationships and effect of naloxone

The clinical course and the drug kinetics are described in a patient who ingested 1.35 g dextropropoxyphene chloride, 17.5 g aspirin, 7.5 g phenazone, 2.5 g butenemal, and 250 mg of a phentiazine derivative. Within 1 h the intoxication caused deep unconsciousness, severe respiratory depression, moderate circulatory failure, and slight quinidine-like changes in the ECG. Despite very high serum concentrations of dextropropoxyphene (peak 1010 micrograms/l at 2 h) and norpropoxyphene (871 micrograms/l at 8 h) the patient responded well to naloxone. No clear signs of the saturation of drug metabolism were found in this patient despite the high serum concentrations of dextropropoxyphene, salicylate, phenazone, and butenemal.