Free Morphine Concentrations Research Articles

Interpretation of GC–MS opiate results in the presence of pholcodine

Although the cross reactivity of pholcodine with opiate immunoassays has been well documented there is little published information the potential for pholcodine interference with chromatographic analyses. Wilson and Smith [Ann. Clin. Biochem. 36 (1999) 592] recently described the ‘misidentification’ of morphine in quality control specimens that had been spiked with pholcodine. This report describes a sensitive, rapid gas chromatography—mass spectrometry (GC–MS) method for the detection and quantitation of pholcodine and morphine, together with 6-monoacetylmorphine (6-MAM), codeine and dihydrocodeine in urine. This method was used to analyse urine specimens collected from volunteers given single and multiple doses of pholcodine to establish the significance this drug on the analytical results obtained when performing drug screening according to the proposed UK and EU legally defensible workplace drug testing guidelines. The maximum urinary free morphine concentration achieved following a single 10mg oral dose of pholcodine was 1.39mg/l at 2–4h post dose. Following multiple 10mg oral doses of pholcodine the maximum urinary free morphine concentration was determined as 0.4mg/l at 170h after the final dose was administered. This apparent anomaly in the morphine concentrations obtained following single and multiple pholcodine doses can be explained in part by differences in the concentration of the specimens, and may be overcome by applying a correction factor for specimen dilution using their creatinine concentration. The data from this study suggests that even following one single 10mg dose of pholcodine, free morphine concentrations greater than both the proposed UK workplace drug testing guidelines threshold of 0.3mg/l total morphine and the proposed European Union threshold of 0.2mg/l total morphine can be achieved. This highlights the need for caution when interpreting confirmatory opiate data, especially in medicolegal and clinical cases, and in cases where the use of pholcodine is suspected.

Assessment of the acuteness of heroin deaths from the analysis of multiple blood specimens.

Data was compiled from 126 morphine-involved cases investigated by the Office of the Chief Medical Examiner, State of Maryland, USA. An investigation was conducted into whether comparison of morphine concentrations from a central and peripheral site could be used to determine whether a morphine death was acute or delayed. Fifty cases were identified as 'acute' because the urine free morphine concentration by radioimmunoassay (RIA) was less than 25 ng/mL; 76 cases were classified as 'random' because they had a urine morphine concentration greater than 25 ng/mL by RIA. The average heart blood to peripheral blood morphine concentration ratio in the acute deaths was 1.40. The average heart blood to peripheral blood morphine concentration ratio in the random deaths was 1.18. Because there was considerable overlap between the two groups of data, the authors conclude that it was not possible to predict 'acute' opiate intoxication deaths versus 'delayed' deaths when the only information available is heart and peripheral blood free morphine concentrations.

Postmortem Blood Free and Total Morphine Concentrations in Medical Examiner Cases

This purpose of this study was to determine the relationships between postmortem free morphine and total morphine levels in a large series of medical examiner morphine and heroin related deaths. Free morphine, total morphine, and 6-monoacetylmorphine (6-MAM) concentrations were measured by gas chromatography-mass spectrometry (GC-MS) in 87 medical examiner cases over 20 months. The mean total morphine concentration, mean free morphine concentration, and mean percent free morphine for all cases were: 2.3 mg/L (SD 5.2 mg/L), 0.5 mg/L (SD 1.6 mg/L), and 19.4% (SD 22.8%); respectively. Regression analyses showed weak correlations between total and free morphine concentrations over the entire concentration range (0 to 36.6 m/L, r = 0.603, n = 91) and over a subset concentration range of 0 to 1.0 mg/L (r = 0.369, n = 54). Twenty-three out of 56 (41%) tested positive for 6-MAM, indicative heroin abuse cases. Lower total and free morphine concentrations and a higher percent free morphine were found in individuals with detectable 6-MAM. Comparing blood concentrations for cases with and without detectable 6-MAM demonstrated mean total morphine concentrations of 0.9 mg/L versus 2.1 mg/L (p = 0.05), mean free morphine concentrations of 0.3 mg/L versus 0.4 mg/L (p = 0.21), and mean percent free morphine of 34.7% versus 13.7% (p < 0.003), respectively. Our findings demonstrate higher free to total morphine ratios in individuals with detectable 6-MAM than in individuals without 6-MAM. The database established in this study may assist medical examiners in the evaluation of postmortem blood opiates regarding the cause of death in opiate related ingestion cases.

Palliative Pain Therapy at the End of Life and Forensic Medicine Issues

An 83-year-old woman with a history of Alzheimer's disease and breast cancer died at home while receiving palliative pain therapy with oral morphine from her family for metastatic breast cancer. Allegations of mistreatment were made, and this case was ultimately referred to the Office of the Chief Medical Examiner, State of Maryland. An autopsy failed to identify any injuries or residual cancer, leaving no anatomic explanation for the pain that had been presumed to be metastatic breast carcinoma involving bone. The blood free morphine concentration was 5,200 ng/ml, and the total morphine concentration was 15,000 ng/ml. This case demonstrates the challenges and difficulties in forensic medicine when faced with the interpretation of toxicologic results at the end of life.

The role of alcohol abuse in the etiology of heroin-related deaths. Evidence for pharmacokinetic interactions between heroin and alcohol.

In order to evaluate pharmacokinetic interactions between heroin and alcohol and their role in the etiology of heroin-related deaths (HRD), the alcohol concentration in blood (BAC), the free (FM) and total morphine (TM) concentrations in blood (determined by DPC Coat-A-Count radioimmunoassay before and after enzymatic hydrolysis), and the TM concentration in urine and bile (DPC Coat-A-Count after enzymatic hydrolysis) in a population of 39 lethal cases included in the records of the Department of Legal Medicine and Public Health at the University of Pavia from the period January 1997-April 1998 were examined. The cause of death in each case was attributed to either heroin or associated heroin-ethanol intoxication. Cases were arbitrarily divided into two groups according to BAC (low-ethanol group, LE, BAC < or = 1000 mg/L and high-ethanol group, HE, BAC > 1000 mg/L). The differences in the FM and TM concentrations in blood, bile, and urine and in the FM/TM ratios between the two . groups were statistically evaluated (Mann-Whitney U test). A similar statistical evaluation was carried out on data from a previously published study concerning the disposition of heroin and its metabolites (6-acetylmorphine and morphine) in blood and urine in 23 lethal cases attributed to either heroin or heroin and alcohol intoxication. The values of the following variables in the LE and HE groups were compared: FM, TM, and 6-acetylmorphine concentrations in blood (6-AM); the FM/ (FM + 6-AM) ratio; the FM/TM ratio; and the urinary concentrations of heroin, 6-acetylmorphine, and free morphine. Statistical analyses of data indicated that high BACs are associated with reduced hydrolysis of 6-AM to morphine (FM/[FM + 6-AM], p = 0.0022) and that a good inverse correlation exists between BAC and hydrolysis of 6-AM to morphine (r2 = 0.67). High BACs were also found to be associated with an increased FM/TM ratio and with reduced excretion of free and total morphine. These results suggest the hypothesis that pharmacokinetic interactions between heroin and alcohol do occur in individuals exposed to high doses of these substances.

Concentrations of morphine and codeine in urine of heroin abusers

We have measured concentrations of morphine, codeine and 6-monoacetylmorphine in urine of people admitted to the Los Angeles County + University of Southern California Medical Center. Of 60 patients positive for morphine and/or codeine, 10 were judged to be heroin abusers based on positive results for 6-monoacetylmorphine, a specific metabolite of heroin. In nine of these ten patients, 0.028–39.4 μg/ml free codeine and 0.070–307 μg/ml total codeine were detected along with 1.74–218 μg/ml of free morphine and 11.2–2870 μg/ml of total morphine; the morphine-to-codeine ratios were 3.65–228 and 2.27–207 for the free forms and total amounts of these opiates, respectively. In the one patient who was negative for codeine, the concentrations of free and total morphine were 0.114 and 2.22 μg/ml, respectively. Based on our data and literature data available, the following criteria are proposed for judging heroin use from the results of urinalysis, especially when no 6-monoacetylmorphine is detected: (1) a detectable amount of free morphine exists and the concentration of total morphine is higher than 10 μg/ml; (2) a detectable amount of codeine exists; and (3) the morphine-to-codeine ratio is higher than 2 for both the free forms and total amounts of these opiates.

Distribution of Free and Conjugated Morphine in Body Fluids and Tissues in a Fatal Heroin Overdose: Is Conjugated Morphine Stable in Postmortem Specimens?

The tissue distribution of free and conjugated morphine in a male individual who died after self-injection of heroin and methamphetamine was investigated, and the postmortem stability of morphine in the blood, liver and urine, and that of 6-monoacetylmorphine in the urine was determined. Confirmation and quantitation of morphine, 6-monoacetylmorphine and methamphetamine were performed by gas chromatography/mass spectrometry and gas chromatography, respectively. Blood levels of free and total morphine were very site-dependent with ranges of 462-1350 and 534-1570 ng/mL, respectively. Large amounts of total morphine, 5220, 4200, and 2270 ng/g, had accumulated in the stomach contents, liver, and lung, respectively. The concentration of free morphine in the cerebrospinal fluid was correlated very closely with that in the cerebrum. The proportion of free morphine in various fluids and tissues ranged from 23.0% to 98.8% of total morphine: less than 30% in the stomach contents and urine; 30-60% in the liver, cerebrospinal fluid, lung, and pericardial sac fluid; 61-90% in the spleen, right femoral muscle, myocardium, blood in the left and right ventricles of the heart, and right femoral vein blood; more than 91% in the right kidney and cerebrum. Detectable amounts of 6-monoacetylmorphine, 417 ng/mL and 78 ng/g, existed in the urine and stomach contents, respectively, indicating that this individual might have died within several hours after heroin injection. Methamphetamine concentrations in the blood were also site-dependent within the range 551-1730 ng/mL. In an in vitro experiment, free and conjugated morphine were stable in the blood and urine at 4, 18-22, and 37 degrees C for a 10-day study period. In the liver, however, conjugated morphine had been converted almost completely to free morphine at 18-22 and 37 degrees C by the end of the experiment, although it was stable at 4 degrees C. Urine 6-monoacetylmorphine, although degraded slightly at 37 degrees C, was stable at 4 and 18-22 degrees C during the experiment. Thus it appears that non-specific hydrolysis of conjugated morphine to free morphine would not occur in corpses at least for a few days after death. Femoral muscle may be a specimen of choice for roughly predicting the ratio of free to total morphine in blood even when blood specimens are not available, because the femoral muscle is relatively spared of both postmortem diffusion of drugs and bacterial invasion.

Distribution of codeine, morphine, and 6-acetylmorphine in vitreous humor.

Two hundred and twenty-three vitreous humor specimens, which were obtained from a medical examiner's office, were found to be opiate positive (cutoff, 50 ng/mL) by fluorescence polarization immunoassay. All samples were analyzed for their free codeine, morphine, and 6-acetylmorphine contents by a gas chromatography-mass spectrometry protocol. 6-Acetylmorphine was found (cutoff, 10 ng/mL) in 41 specimens in the concentration range of 10-125 ng/mL. Twenty specimens had a free codeine-free morphine concentration ratio > or = 1. Eighty-five samples that were found to contain 50 ng/mL free morphine were further analyzed for their total codeine and total morphine contents. Total codeine-total morphine concentration ratios in 8 (of the 85 samples) were > or = 1, whereas this ratio in the others (only those with a codeine concentration high than 15 ng/mL were included) was significantly lower than 1. The codeine-morphine concentration ratio in vitreous humor appears to resemble that reported for blood and urine and can be used as the basis for differentiating between codeine- and morphine- (heroin-) induced fatalities.

Effectiveness of a jet injection system in administering morphine and heparin to healthy adults

Jet injection eliminates the risk of contaminated needlestick injuries when giving intramuscular or subcutaneous medications. Clinical efficacy of the Biojector System was equivalent to that of needle and syringe injection in unpublished trials with vaccines, but had not been studied using other drugs. To compare the effectiveness of the Biojector with conventional needle and syringe injection in administering intramuscular morphine and subcutaneous heparin to healthy adults, as measured by plasma drug concentration. Intramuscular injections of morphine 8 mg (5 mg if weight < or = 65 kg) were given 24 hours apart with the jet injector and with a needle and syringe to 30 subjects at the deltoid site and 10 subjects at the dorsogluteal site. Blood samples for plasma concentrations of free morphine were drawn at 15, 30, 45, 60, 120, and 240 minutes and were analyzed using radioimmunoassay. Abdominal subcutaneous injections of heparin 3500 U were given every 8 hours for 5 days with both injection methods to 29 subjects, with 48 hours between the two series. Daily blood samples for plasma heparin were analyzed by colorimetric assay for antifactor Xa activity. Mean free morphine concentration, peak value, and area under the curve did not differ significantly between the deltoid and dorsogluteal sites or between the jet injector and needle and syringe. Values of mean daily heparin concentrations and area under the curve were low and did not differ between the two injection methods. Plasma drug concentrations provided by the Biojector were equivalent to those provided by conventional needle and syringe when administering intramuscular morphine and low-dose subcutaneous heparin.

Storage temperature effect on the stability of morphine and codeine in urine.

Urine samples collected from one laboratory volunteer and five alleged heroin addicts are prepared (without preservatives) in 5-mL aliquots in glass culture tubes and stored at room, refrigerator, and freezer temperatures. Total morphine, total codeine, free morphine, and free codeine in these samples are analyzed at 30-day intervals for an 11-month period. Total morphine and total codeine concentration decreases are observed for all specimens in all storage conditions. For samples stored in the refrigerator and freezer, similar concentration decrease patterns are observed for total morphine and total codeine, and the decreases range from approximately 10 to 40%. The concentrations of free morphine and free codeine show slight but steady increases. For samples stored at room temperature, large decreases of total morphine are observed for three out of 10 specimens, and total codeine and total morphine concentrations (in seven other specimens) show a decrease pattern similar to that observed for the freezer and refrigerator storage conditions. Three concentration change patterns are observed for free morphine: The type I pattern follows the same decrease pattern observed for freezer and refrigerator storage conditions; the type II pattern shows free morphine increases (after 30-90 days of storage) that remain relatively high for the entire 11-month period; and the type III pattern shows initial increases, followed by gradual decreases to levels that are comparable with the specimens' respective initial concentrations. Free codeine concentrations show slight and steady increases for the entire 11-month period in all specimens.

The Role of Ethanol in Heroin Deaths

The purpose of this study was to evaluate the role of ethanol in deaths due to heroin intoxication. Over a 12 month period, all cases investigated by the Office of the Chief Medical Examiner, State of Maryland where a blood screen by Roche Abuscreen radioimmunoassay (RIA) was positive at a cutoff of 100 ng/mL were included in the study. Free morphine was quantitated using the Coat-A-Count RIA and ethanol was quantitated by head space gas chromatography. All presumptive morphine positive cases were confirmed by gas chromatography/mass spectrometry. Seventy of the 119 cases where death was attributed to narcotic or alcohol and narcotic intoxication had blood ethanol concentrations (BAC) greater than or equal to 0.02 g/dL; 48 had BAC > or = 0.10 g/dL. Only 3 of 45 cases where morphine was identified but was unrelated to death had BAC > or = 0.02 g/dL. At all ranges of free morphine concentrations, there was a greater percentage of narcotic deaths when ethanol was present. From the data, we conclude that 1) the use of even small amounts of ethanol with heroin is clearly a risk factor in deaths due to heroin, 2) there are some heroin deaths where no free morphine is identified in the blood. In these deaths, ethanol is unlikely to be present, 3) at blood ethanol concentrations between 0.20 and 0.29 g/dL, the morphine concentrations in heroin deaths increased significantly, 4) at blood ethanol concentrations greater than 0.30 g/dL, morphine became less of a factor than the ethanol in causing death.

Disposition of heroin and its metabolites in heroin-related deaths.

Although many deaths occur annually from heroin intoxication, the presence of heroin has not been reported in postmortem tissues. Recognizing heroin's susceptibility to rapid chemical and metabolic hydrolysis, extraction procedures were developed for the efficient recovery of heroin, 6-acetylmorphine, and morphine from postmortem tissue utilizing solid-phase extraction coupled with gas chromatography/mass spectrometry. From heroin-related deaths, 21 sets of blood and urine specimens were collected. The mode of death in these cases was categorized as rapid, delayed, or undetermined. Compared with delayed deaths, rapid deaths were characterized by the following trends: higher mean concentrations of 6-acetylmorphine, free morphine, and total opiates in blood; a higher ratio of free morphine concentrations to total opiate concentrations in blood; lower mean concentrations of 6-acetylmorphine and morphine in urine; greater likelihood of 6-acetylmorphine detection in blood; and lesser likelihood of heroin detection in urine. The study also included analysis of multiple tissue specimens from two subjects who died of heroin intoxication. Heroin was identified in urine and injection-site tissue. Concentrations of 6-acetylmorphine in cerebrospinal fluid, spleen, and brain were substantially higher than in blood, liver, lung, and kidney. All specimens were positive for morphine. Heroin metabolites were detected in hair specimens. The identification of heroin and 6-acetylmorphine in biological tissues effectively established the presence of heroin in cases of acute narcotic intoxication. These studies demonstrated that measurement of heroin and its metabolites provides useful information for the differential diagnosis of heroin-related deaths.

Forensic Drug Testing For Opiates. II. Metabolism and Excretion Rate of Morphine In Humans After Morphine Administration

Urine levels of free and total morphine were determined by GC/MS for four male subjects who received single doses of 20 mg of morphine sulfate intramuscularly. Peak concentrations were observed within 10 h for both conjugated and free morphine; thereafter, levels declined rapidly. Initially, free morphine represented from 25 to 34% of the total amount of morphine present, but this ratio declined after 12 h to an average of only 5.9% of total morphine. Free morphine accounted for an overall mean of 6.8% of the dose excreted in urine and conjugated morphine for 58.6%. The mean excretion half-life for free morphine was 6.6 h and for conjugated morphine was 8.2 h. The lower concentration and shorter half-life of free morphine resulted in a shorter detection time for free morphine versus total morphine at a 300-ng/mL cutoff. An equivalent detection time for free morphine was obtained when its cutoff was lowered to 25 ng/mL. The possibility that morphine is metabolized to codeine was unequivocally ruled out by the finding of an absence of codeine at or above the LOD of the GC/MS assay in all clinical specimens collected after morphine administration.

Postmortem disposition of morphine in rats

The antemortem and postmortem distribution of morphine was studied in rats for the purpose of establishing whether drug distribution is altered after death. Samples were examined for free and total morphine concentration, pH and water content at 0–96 h after death. Morphine was administered antemortem at various intervals. All groups of rats studied showed a significant ( P < 0.05) increase in postmortem cardiac blood morphine concentrations. These changes, which are detectable within 5 min after death are likely to be related to an observed, rapid decrease in cardiac blood pH from 7.34 ± 0.02 to 6.74 ± 0.05. Significant increases in free morphine levels were, also, observed 24 and 96 h after death in liver, heart and forebrain while urine morphine levels decreased. The liver showed the greatest increase (20-fold) in free morphine levels 96 h after death, while hindbrain levels did not significantly change. Bacterial hydrolysis of morphine glucuronides accounted only in part for the observed increase in free morphine concentration. Postmortem fluid movement and pH-dependent drug partitioning was detected. It would appear that several mechanisms are responsible for postmortem drug distribution. Understanding the mechanisms and patterns responsible may eventually lead to better choices of postmortem tissue which may better represent antemortem drug levels.

Effect of premedication with controlled‐release oral morphine on postoperative pain

Thirty fit patients presenting for elective total hip replacement were randomly allocated to receive a premedication of 60 or 90 mg controlled-release oral morphine or 15 mg intramuscular morphine. Postoperative analgesia was assessed using on-demand intravenous pethidine supplementation requirements. In 15 patients free plasma morphine concentrations were measured. Both 60 and 90 mg controlled-release oral morphine led to a reduced pethidine requirement compared to the intramuscular group but the reduction was not statistically different.

Determination of morphine in biological samples by gas chromatography—mass spectrometry: Evidence for persistent tissue binding in rats twenty-two days post-withdrawal

Combined gas chromatography—mass spectrometry with capillary and packed column gas chromatography and a deuterium-labelled internal standard was used to determine morphine in biological specimens from rats 22 days after abrupt withdrawal. Morphine was extracted from urine and body organs at pH 9 and the pentafluoropropionyl derivatives were made for analysis by gas chromatography—mass spectrometry. The stationary phase was OV-17 and the mass spectrometer was focused on m/z 414 for morphine and m/z 417 for the internal standard, [NC 2H 3]morphine. With fused-silica capillary columns, the sensitivity of the assay was increased about ten-fold over packed columns. Urinary excretion of total morphine (free + conjugated) was 22 ng/h (range 11–51 ng/h, n = 8) at 22 days post-withdrawal. Free morphine was mainly detected in the lung (1.8–6.5 ng/g, n = 7), kidney (1.5–4.0 ng/g, n = 7) and liver (1.8–4.6 ng/g, n = 4). Traces of morphine were also detected in brain of some rats. Treatment with the opiate antagonist naltrexone, 10 mg/kg on four consecutive days before death, failed to change the urinary excretion pattern or the concentration of free morphine in body organs. The biological significance of the residual morphine, if any, remains to be determined.

Homogeneous Enzyme Immunoassay for Opiates in Urine

Abstract An assay technique, homogeneous enzyme immunoassay, is described for the quantitative determination of morphine derivatives in biological fluids. An enzyme is labeled with morphine. When the enzyme-labeled morphine is bound by antimorphine antibodies, the enzyme is rendered inactive. Free morphine competes with enzyme—morphine for antibody binding sites preventing inhibition of enzyme activity. Enzyme activity is thus directly related to the concentration of free morphine. See PDF for Equation Where the enzyme used is lysozyme, the assay can detect 0.5 µg of morphine per milliliter of urine with &amp;gt;95% confidence (CV, 5.0% at 0.5 µg/ml morphine). The technique gave nearly twice as many confirmed positives as did thin-layer chromatography in a comparative study of urines from a methadone maintenance program. The immediacy of the results (assay time: &amp;lt;1 min) permits use of the assay in hospital emergency rooms, law-enforcement facilities, and methadone treatment programs.