Comparison of drug concentrations taken from clamped and unclamped femoral vessels.

Postmortem drug concentrations may vary depending on sampling site, volume of blood collected, and method of sampling, making it important to analyze specimens from different sites in the body to detect postmortem redistribution and avoid erroneous conclusions on cause and manner of death. Using a blind stick method to draw large amounts of blood from the femoral vessel may increase the likelihood of contamination with blood from more central sites. It has been suggested that clamping the femoral vessel before drawing the sample may eliminate possible contribution from central sites. Eight drugs from four different drug classes were evaluated to determine the difference between drug concentrations in clamped and blind stick femoral blood. Drug concentrations of three selective serotonin reuptake inhibitors, or SSRIs (sertraline, paroxetine, citalopram), two benzodiazepines (diazepam and alprazolam), two antihistamines (diphenhydramine and promethazine), and one opiate (hydrocodone) were evaluated in clamped femoral blood, blind stick femoral blood, and heart blood and compared using concentration ratios and linear regression analysis. Clamped femoral blood concentrations and blind stick femoral blood concentrations were found to have good predictability across all drug classes with ratios around 1.0, indicating good correlation between blind stick femoral and clamped femoral samples. Therefore, it can be concluded that a blind stick femoral blood sample does not have significant redistribution from central sites and is of equivalent quality to a clamped femoral sample.