Acute intoxication with guaifenesin, diphenhydramine, and chlorpheniramine

Mixed drug reactions are frequently encountered in emergency department overdose cases and also in fatal intoxications. Assessment of the relative contribution of each drug in producing adverse effects is often compounded by lack of case history and the paucity of cases reported in the literature. This report describes a fatal intoxication with three common over-the-counter medications: guaifenesin, diphenhydramine, and chlorpheniramine. A 48-year-old woman was found dead in the attic bedroom of her residence. Specimens obtained at autopsy for toxicologic analysis included heart blood, urine, bile, gastric contents, vitreous humor, and cerebrospinal fluid. The over-the-counter drugs were identified and quantitated by acid/neutral or basic liquid-liquid extraction followed by gas chromatographic analysis with nitrogen phosphorus detection. Concentrations of guaifenesin, diphenhydramine, and chlorpheniramine detected in the heart blood were 27.4, 8.8, and 0.2 mg/L, respectively. The cause of death was determined to be acute intoxication by the combined effects of guaifenesin, diphenhydramine, and chlorpheniramine, and the manner of death was determined to be suicide. To our knowledge, the blood guaifenesin concentration in this case is the highest reported concentration to date associated with an acute intoxication.