Morphine-3-D Glucuronide Stability in Postmortem Specimens Exposed to Bacterial Enzymatic Hydrolysis

Abstract

Medical examiners frequently rely on the finding of free morphine present in postmortem specimens to assist in certifying deaths associated with narcotics. In vitro hydrolysis of morphine-3-D glucuronide (M3DG) to free morphine was studied using variable specimen pH, initial degree of specimen putrefaction, storage temperature and time, and the effectiveness of sodium fluoride (NaF) preservation. Reagent M3DG was added to opiate-free fresh blood and urine and to autopsy-derived blood specimens. Reagent bovine glucuronidase was also added to certain specimens. Freshly collected and refrigerated NaF-preserved blood produced minimal free morphine, whereas four of five autopsy blood specimens produced free morphine from M3DG. Increased storage time, temperature, and initial degree of putrefaction resulted in greater free morphine generation despite the absence of viable bacteria. Hydrolysis occurring during specimen storage can generate free morphine from M3DG and may result in erroneous conclusions in certifying narcotic deaths.

Postmortem toxicology of drugs of abuse

“…De-conjugation of morphine metabolites to morphine has been observed in liver [88]. Morphine is relatively stable in specimens when stored frozen, but shows significant losses when stored at 4 8C or higher for more than a few days, or in postmortem specimens [89,90]. This issue has been more recently discussed in the Shipman murders [18].…”

Stability studies of amphetamine and ephedrine derivatives in urine

“…This issue increased the interest of toxicological laboratories to ensure that analyte instability will not affect analytical results during the retesting period. A large body of data is available on the stability in urine of phencyclidine [7][8][9], lysergic acid diethylamide [9][10][11][12][13], cannabinoids [8][9][10][11][12][13][14][15][16][17][18][19][20], morphine and codeine [8,9,17,[21][22][23][24][25][26], and cocaine/benzoylecgonine [8,10,15,17,[26][27][28][29].…”

Investigation of morphine and morphine glucuronide levels and cytochrome P450 isoenzyme 2D6 genotype in codeine-related deaths

“…In our study blood specimens were collected from the femoral artery, which lessens the potential for post-mortem changes due to redistribution. Post-mortem hydrolysis of morphine glucuronides has been shown to yield elevated morphine levels during specimen storage above À20 8C [41,42].…”