Prevalence of dihydrocodeine in hydrocodone positive postmortem specimens.

Hydrocodone (HC) has received renewed interest in the US due to reported increases in opiate related deaths involving psychotherapeutic drugs. The relative contribution of dihydrocodeine (DHC) in these deaths is unknown since little testing of this compound is performed. The objective of the study was to determine the prevalence of DHC in HC positive decedents and report the range of concentrations detected in these cases in order to evaluate the potential role of DHC in the deaths and determine the usefulness of including this analyte in opioid testing protocols. Specimens were assayed by liquid-liquid or solid phase extraction followed by gas chromatography/mass spectrometry operated in the selected ion monitoring mode. A multipoint calibration was utilized in the linear range 2-600ng/mL. Accuracy for HC, DHC and hydromorphone (HM) was 101-106% and between day precision at 160ng/mL between 7% and 11%. One hundred and thirty six cases were identified with the majority male (62%) and white (83%). A search of HC positive cases identified 64 with DHC (47%). The range of HC concentrations was 9-3039ng/mL heart blood (n=43) and 42-12353ng/mL urine (n=21). DHC concentrations in these cases ranged 3-243ng/mL in heart blood and 5-1842ng/mL in urine. DHC/HC ratios ranged 0.00(7)-2.90 in blood (n=43), and 0.01-5.04 in urine (n=21) with 16% and 24% of these cases with ratios >0.50, respectively. HM was detected in only 9 HC cases with the majority positive in urine.