Methylephedrine concentrations in blood and urine specimens.

Methylephedrine is a sympathomimetic amine that appears in many over-the-counter cough and cold medications throughout the world. The abuse of methylephedrine-containing medications has been reported in Japan. Although methylephedrine is not available in the United States, it was identified in 15 cases received by the Forensic Toxicology Laboratory, Division of Forensic Toxicology, Office of the Armed Forces Medical Examiner, Armed Forces Institute of Pathology over a two-year period; 12 of the 15 cases were collected from patients or decedents located within the confines of the continental United States. Methylephedrine was identified in each case by gas chromatography-nitrogen-phosphorus detection following an alkaline extraction and subsequently confirmed using full scan electron impact mass spectrometry. Quantitation of underivatized methylephedrine was performed using the same technique. Blood methylephedrine concentrations ranged from less than 0.05 to 0.28 mg/L (n = 14), and the mean methylephedrine concentration in urine was 1.6 mg/L (range, 0.15-6.8, n = 11 [excluding case 6]). A literature search revealed little information pertaining to the interpretation of methylephedrine concentrations in the blood. Six of the 15 cases presented here were positive for methylephedrine in the blood. Three of these cases were postmortem cases, and the other three cases were nonfatal aircraft mishaps. There is no evidence in any of these cases that methylephedrine was present at toxic concentrations; therefore, it appears from the cases reviewed in this study that blood methylephedrine concentrations less than 0.3 mg/L are not associated with significant toxicity.