Postmortem distribution of guaifenesin concentrations reveals a lack of potential for redistribution

• Non-toxic postmortem guaifenesin blood and liver concentrations are presented.
• Guaifenesin may be considered non-toxic to at least 5.4 mg/L in peripheral blood.
• Median guaifenesin central blood to peripheral blood ratio was 1.1.
• Liver to peripheral blood ratios showed a median value of 0.9 L/kg.
• Guaifenesin is not prone to substantial postmortem redistribution.

Therapeutic (or non-toxic) postmortem guaifenesin blood and liver concentrations have not been previously described. Peripheral blood guaifenesin concentrations were compared to central blood and liver concentrations in eight medical examiner cases. Specimens were initially screened for alcohol and simple volatiles, drugs of abuse, alkaline, and acid/neutral drugs. Guaifenesin, when detected by the acid/neutral drug screen, was subsequently confirmed and quantified by a high performance liquid chromatography procedure. Data suggest that postmortem guaifenesin peripheral blood concentrations may be considered non-toxic to at least 5.4 mg/L with liver concentrations to at least 7.0 mg/kg. Overall, guaifenesin concentrations ranged from 1.9 to 40 mg/L in peripheral blood, 2.2–150 mg/L in central blood, and 2.6–36 mg/kg in liver. The median guaifenesin central blood to peripheral blood ratio was 1.1 (N = 8). Similarly, liver to peripheral blood ratios showed a median value of 0.9 L/kg (N = 5). Given that a liver to peripheral blood ratio less than 5 L/kg is consistent with little to no propensity for postmortem redistribution, these data suggest that guaifenesin is not prone to substantial postmortem redistribution.