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 1.39 mg/l at 2-4h post dose. Following multiple 10mg oral doses of pholcodine the maximum urinary free morphine concentration was determined as 0.4 mg/l at 170 h 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.     

Post-mortem drug redistribution--a toxicological nightmare

Detailed human case data is presented to illustrate the dramatic extent of the phenomenon of post-mortem drug redistribution. The data suggests that there is a post-mortem diffusion of drugs along a concentration gradient, from sites of high concentration in solid organs, into the blood with resultant artefactual elevation of drug levels in blood. Highest drug levels were found in central vessels such as pulmonary artery and vein, and lowest levels were found in peripheral vessels such as subclavian and femoral veins. In individual cases, in multiple blood samples obtained from ligated vessels, concentrations of doxepin and desmethyldoxepin ranged from 3.6 to 12.5 mg/l and 1.2 to 7.5 mg/l, respectively; amobartital, secobarbital and pentobarbital from 4.3 to 25.8 mg/l, 3.9 to 25.3 mg/l and 5.1 to 31.5 mg/l respectively; clomipramine and desmethylclomipramine from 4.0 to 21.5 mg/l and 1.7 to 8.1 mg/l, respectively and flurazepam 0.15 to 0.99 mg/l; imipramine and desipramine from 4.1 to 18.1 mg/l and 1.0 to 3.6 mg/l, respectively. We conclude that this poorly studied phenomenon creates major difficulties in interpretation and undermines the reference value of data bases where the site of origin of post-mortem blood samples is unknown.     

Postmortem absorption of drugs and ethanol from aspirated vomitus--an experimental model.

Using human cadavers an experimental model was developed to simulate the agonal aspiration of drug- and alcohol-laden vomitus. By needle puncture, an acidified (N/20 HCl) 60-ml slurry of drugs (paracetamol 3.25 g, dextropropoxyphene 325 mg) and ethanol 3% w/v was introduced into the trachea. After 48 h undisturbed at room temperature, blood samples were obtained from ten sites. Ethanol and drug concentrations were highest in the pulmonary vessels in all five cases studied. Pulmonary vein mean ethanol was 58 mg% (range 13-130), paracetamol 969 mg/l (range 284-1934), propoxyphene 70 mg/l (range 11-168). Pulmonary artery mean ethanol was 53 mg% (range 10-98), paracetamol 476 mg/l (range 141-882), propoxyphene 29 mg/l (range 7.6-80). Ethanol and drug concentrations in aortic blood were higher than in the left heart and concentrations in the superior vena cava were higher than in the right heart, suggesting direct diffusion into these vessels rather than diffusion via the pulmonary and cardiac blood. Potential interpretive problems arising from this phenomenon can be avoided by using femoral vein blood for quantitative toxicological analysis.     

Evaluating suspected co-proxamol overdose.

In three instances of suicidal poisoning by co-proxamol (paracetamol and dextropropoxyphene) blood samples were obtained from 11 sites together with eight tissue samples, bile, urine, gastric contents and duodenal contents. Site-dependent differences in blood propoxyphene concentration varied between the three cases but concentrations were consistently lowest in peripheral blood and highest in central sites: 3.9-5.5 (pulmonary vein) mg/l; 4.6-25 (pulmonary vein) mg/l; 3.2-40 (aorta) mg/l. There was a less than twofold variation in corresponding blood paracetamol concentrations. Reference data on fatal propoxyphene blood concentrations do not specify the blood sampling site and can be misleading. The intra-individual variability of propoxyphene concentrations in blood in these three cases underscores this problem. Tissue concentrations of propoxyphene showed considerable inter-individual variability in degree and pattern. Tissue concentrations of paracetamol showed a less than twofold intra-individual variation. Body drug loads were calculated by two methods: from organ weights and tissue concentrations; from published volume of distribution data (Vd). For paracetamol the body drug load is underestimated by the organ weight calculation but the Vd calculation approximates the suspected dose based on anamnestic information. For propoxyphene the body drug load is seriously underestimated by the organ weight calculation and overestimated up to 2.5 times by the Vd calculation. Since the two drugs have a fixed ratio in co-proxamol then the dose of propoxyphene (the effective lethal agent) can be inferred from the paracetamol dose calculated by Vd. This approach may be applicable to cases of overdose with other compounded drug preparations.     

Postmortem concentrations of citalopram

The postmortem concentrations of citalopram in blood, bile, liver, and vitreous humour were investigated in 14 cases using a specially developed high performance liquid chromatography assay. Concentrations from drug and non-drug related deaths were categorized to determine a postmortem therapeutic and toxic range. Therapeutic citalopram concentrations for blood, bile, liver, and vitreous humour ranged to 0.4 mg/L, 2.1 mg/l, 6.6 mg/kg, and 0.2 mg/L, respectively. In one potentially fatal response to citalopram, concentrations were 0.8 mg/L, 6.0 mg/L, 0.3 mg/L for blood, bile and vitreous humour, respectively.     

Mixed drug intoxication involving zaleplon ("Sonata")

Zaleplon ("Sonata") is a pyrazolopyrimidine derivative approved for use in the United States for the treatment of insomnia. To date, there has been little data in the toxicological literature where zaleplon has been implicated as causing a fatal intoxication, either alone or in combination with other drugs. This report documents a case where zaleplon was identified in a suicide by multiple drug ingestion. The following zaleplon concentrations were found: heart blood 2.2mg/l; bile 8.6mg/l and urine 1.4mg/l. Zaleplon was also detected but not quantitated in the kidney and liver.     

Gamma hydroxybutyric acid (GHB) concentrations in humans and factors affecting endogenous production

The endogenous nature of the drug of abuse gamma hydroxybutyric acid (GHB) has caused various interpretative problems for toxicologists. In order to obtain data for the presence of endogenous GHB in humans and to investigate any factors that may affect this, a volunteer study was undertaken. The GHB concentrations in 119 urine specimens from GHB-free subjects and 25 urine specimens submitted for toxicological analysis showed maximal urinary GHB concentrations of 3mg/l. Analysis of 15 plasma specimens submitted for toxicological analysis detected no measurable GHB (less than 2.5mg/l). Studies in a male and female volunteer in which different dietary food groups were ingested at weekly intervals, showed significant creatinine-independent intra-individual fluctuation with overall urine GHB concentrations between 0 and 2.55, and 0 and 2.74mg/l, respectively. Urinary concentrations did not appear to be affected by the particular dietary groups studied.The concentrations measured by gas chromatography with flame ionisation detection (GC-FID) and gas chromatography with mass spectrometry (GC-MS) lend further support to the proposed urinary and plasma interpretative cut-offs of 10 and 4mg/l, respectively, where below this it is not possible to determine whether any GHB detected is endogenous or exogenous in nature.     

The study of metabolite-to-parent drug ratios of methamphetamine and methylenedioxymethamphetamine in hair

The metabolite-to-parent drug ratios were determined in the hair of 2444 methamphetamine (MA) abusers who had produced MA-positive hair results from 2001 to May 2005 and in the hair of 53 ecstasy abusers who had produced positive methylenedioxymethamphetamine (MDMA) hair results from 2002 to May 2005. For the hair analyses, hair strands were washed, cut into small pieces and extracted for 20 h in 1 mL methanol containing 1% HCl. Drugs in the extract were determined by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring after derivatization with trifluoroacetic anhydride. The six range groups were divided as follows on the basis of MA concentrations in hair (n = 2389): 0.5-5 ng/mg (n = 950), 5-10 ng/mg (n = 582), 10-20 ng/mg (n = 503), 20-30 ng/mg (n = 160), 30-40 ng/mg (n = 80), more than 40 ng/mg (n = 114) to assess the correlations between MA concentrations and metabolite-to-parent drug ratios. In groups of higher MA concentrations, lower ratios of AP/MA were found, and there was a statistically significant difference among six range groups. Comparisons of age groups (tens, twenties, thirties, forties, fifties, and sixties) and male and female subjects for the ratios of AP/MA showed a statistically significant difference. The detection of metabolites and the parent drug with reasonable ratios was found to be a useful indicator for distinguishing internal drug incorporation from external contamination. In our study, MA users can produce 0.4-116% (mean = 9%) of amphetamine (AP) concentrations in hair, and ecstasy users 1-110% (mean = 12%) of methylenedioxyamphetamine (MDA) in appropriately washed hair samples.     

Effect of post-mortem changes on peripheral and central whole blood and tissue clozapine and norclozapine concentrations in the domestic pig (Sus scrofa)

Interpretation of the results of psychoactive or other drug measurements in post-mortem blood specimens may not be straightforward, in part because analyte concentrations in blood may change after death. There is also the issue of comparability of plasma (or serum) results to those obtained in whole blood. To investigate these problems with respect to clozapine, this drug (10mg/kg daily) was given orally to two pigs. Blood was collected 3h post-dose on day 7, the animals were sacrificed, and blood taken from central and peripheral veins for up to 48 h after death. Tissue samples were also collected immediately after death and at 48 h. Ante-mortem whole blood clozapine/N-desmethylclozapine (norclozapine) concentrations were 0.86/1.07 and 1.11/1.15 mg/l in pigs 1 and 2, respectively. Blood clozapine and norclozapine concentrations generally increased after death (central vein: clozapine up to 300%, norclozapine up to 460%; peripheral vein: clozapine up to 155%, norclozapine up to 185%). Initial blood and kidney clozapine and norclozapine concentrations were comparable in both animals, but were some two-fold higher in heart, liver and striated muscle in pig 2. In both animals, the heart and striated muscle clozapine and norclozapine concentrations had increased some two- to three-fold at 48 h, whilst the liver and kidney concentrations were essentially unchanged. The reason for the increase in heart and striated muscle concentrations at 48 h is unclear, but could be simple variation in sample site. The plasma:whole blood distribution of clozapine and norclozapine was studied in vitro. In human blood (one volunteer donor, haematocrit 0.50) the plots of plasma versus whole blood concentration were linear for both analytes across the range 0.1-1.5mg/l, although clozapine favoured plasma (plasma:whole blood ratio=1.12), whereas norclozapine favoured whole blood (ratio 0.68). In pig blood, the plots of plasma versus whole blood were non-linear in both cases, although clozapine favoured plasma to a greater extent than norclozapine. This may be due to lower plasma clozapine and norclozapine protein binding capacity in the pig as compared to man.     

Concentrations of cocaine and its major metabolite benzoylecgonine in blood samples from apprehended drivers in Sweden

Cocaine and its major metabolite benzoylecgonine (BZE) were determined in blood samples from people arrested in Sweden for driving under the influence of drugs (DUID) over a 5-year period (2000-2004). Venous blood or urine if available, was subjected to a broad toxicological screening analysis for cannabis, cocaine metabolite, amphetamines, opiates and the major benzodiazepines. Verification and quantitative analysis of cocaine and BZE in blood was done by gas chromatography-mass spectrometry (GC-MS) at limits of quantitation (LOQ) of 0.02mg/L for both substances. Over the study period 26,567 blood samples were analyzed and cocaine and/or BZE were verified in 795 cases (3%). The motorists using cocaine were predominantly men (>96%) with an average age of 28.3+/-7.1 years (+/-standard deviation, S.D.). The concentration of cocaine was below LOQ in 574 cases although BZE was determined at mean, median and highest concentrations of 0.19mg/L, 0.12mg/L and 1.3mg/L, respectively. In 221 cases, cocaine and BZE were together in the blood samples at mean and (median) concentrations of 0.076mg/L (0.05mg/L) and 0.859mg/L (0.70mg/L), respectively. The concentrations of BZE were always higher than the parent drug; mean BZE/cocaine ratio 14.2 (median 10.9) range 1-55. Cocaine and BZE were the only psychoactive substances reported in N=61 cases at mean (median) and highest concentrations of 0.095 (0.07) and 0.5mg/L for cocaine and 1.01 (0.70) and 3.1mg/L for BZE. Typical signs of drug influence noted by the arresting police officers included bloodshot and glossy eyes, agitation, difficulty in sitting still and incoherent speech.     

Urinary excretion of benzoylecgonine following ingestion of Health Inca Tea

Four males ingested one cup of Health Inca Tea which contained 1.87 mg of cocaine. Urine specimens collected for 36 h post-ingestion were analyzed for benzoylecgonine (BE) by EMIT-d.a.u., TDx and gas chromatography/mass spectrometry (GC/MS). Positive immunoassay results were obtained for 21-26 h post tea ingestion. Discrepant immunoassay results occurred with only one specimen: EMIT positive; TDx negative, 0.25 mg/l; GC/MS, 0.273 mg/l. Quantitative TDx results were well correlated with GC/MS results, r2 = 0.963, n = 45. Maximum urinary BE concentrations ranged from 1.4-2.8 mg/l, occurring from 4-11 h, post ingestion. Total BE excretion in 36 h ranged from 1.05 to 1.45 mg, 59-90% of the ingested cocaine dose. Urinary excretion rate constant (Km) ranged from -0.073 to 0.111/h. Health Inca Tea ingestion should be considered when interpreting urinary BE concentrations.     

Death during patient-controlled analgesia: piritramide overdose and tissue distribution of the drug

We report about a fatality during patient-controlled analgesia (PCA). Piritramide peripheral blood concentration was measured with 0.1 mg/l and exceeded the normal therapeutic range. Therefore, a fatal overdose was considered as the cause of death with respiratory depression as the underlying pathophysiological mechanism. The tissue distribution was studied; highest concentrations of piritramide were measured in kidney, bile and urine. Due to a large volume of distribution a difference in the drug concentration found in heart and peripheral bloods the phenomenon of drug redistribution was observed. Confronted with toxicological results, investigations revealed, that the PCA pump had been changed during a previous servicing from displaying mg/h to ml/h, therefore, the anesthetist had entered "1.5" assuming mg/h, but actually applying 1.5 ml/h (which was therefore equivalent to 2.25 mg/h, given a concentration in the cartridge of 1.5 mg piritramide/ml). In total, 61.5 ml (instead of 61.5 mg) had been infused, equivalent to 92.25 mg piritramide. This case report is a further example that human errors can play a crucial role in the safety of medical equipment. Experts in anesthesia recommended human factors engineering design principles to improve the safety of medical devices.     

Postmortem tissue concentrations of venlafaxine

Venlafaxine is a phenethylamine antidepressant which inhibits both serotonin and norepinephrine reuptake and is structurally unrelated to the serotonin reuptake inhibitors (SSRIs). Its major metabolite, O-desmethylvenlafaxine (ODV), also inhibits serotonin reuptake. Although metabolized by the cytochrome P-450 (CYP) system, venlafaxine inhibits CYP 2D6 and 3A4 to a far lesser extent than do the SSRIs. Mechanisms of drug action are reviewed and evaluated in the investigation of 12 fatalities occurring over a 6-month-period where venlafaxine was detected.Venlafaxine and ODV were identified by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure ionization (API) electrospray in positive mode following an n-butyl chloride extraction. Postmortem tissue concentrations studied in each of 12 postmortem cases for venlafaxine and ODV, were 0.1-36 and <0.05-3.5mg/l (peripheral blood), <0.05-22 and <0.05-9.9mg/kg (liver), <0.05-10 and <0.05-1.5mg/l (vitreous), <0.05-53 and <0.05-6.8mg/l (bile), <0.05-55 and <0.05-21mg/l (urine), respectively, and 0.1-200mg of venlafaxine in the gastric contents. Venlafaxine was typically present with other drugs, including other antidepressants, alcohol, and benzodiazepines. The potential for interaction with each drug is discussed. Over the 6-month-period of this study, there were no deaths ascribed solely to venlafaxine intoxication.     

Tetrahydrocannabinols in hair of hashish smokers

The study investigates the presence of tetrahydrocannabinols in the head hair and the pubic and axillary hair. The hair samples were obtained from hashish smokers. The concentrations were determined by radioimmunoassay and reflect total tetrahydrocannabinols and metabolites. The values found ranged from 0.4 ng/mg hair up to 3.8 ng/mg hair. The presence of the drug in the hair samples was also demonstrated by GC/MS.     

Amoxapine fatalities: three case studies

Amoxapine (Asendin), a recently introduced dibenzoxazepine, has been effective in clinical studies for the treatment of various types of depression. Three amoxapine-related deaths are reported. Quantitation of amoxapine was carried out by gas chromatography using 3% OV-17 column. Blood amoxapine concentrations were 11.5 mg/l, 2.8 mg/l, and 0.89 mg/l. The concentrations are many-fold higher than the reported therapeutic serum concentrations of 0.21 mg/l. These cases illustrate the potential toxicity and lethality of amoxapine overdose and the need for caution in prescribing a large amount of amoxapine to patients with suicidal tendencies.     

Postmortem distribution of sertraline and desmethylsertraline in a fatality

Sertraline (CAS 79617-96-2) is a relatively safe medication for patients suffering from depression. Data reporting the postmortal distribution of sertraline and desmethylsertraline remain rare as well as reports of risks of side effects following ingestion of the drug. In a case of a young woman found dead in her flat sertraline and desmethylsertraline were identified and quantified in body fluids and tissues by gas chromatography/mass spectrometry and high performance liquid chromatography with diode array detection after alkaline extraction. Sertraline and its desmethyl metabolite were found in the peripheral blood in levels of 0.15 mg/l and 0.20 mg/l, concentrations in liver and bile were markedly higher. By exclusion of other reasons for death a lethal sertraline intoxication was decided. Sertraline is suggested to possess a low inherent toxicity, however, a risk of side-effects which may occur in single cases even under moderate dosages should be considered.     

Comparison of ethanol concentrations in venous blood and end-expired breath during a controlled drinking study

Concentration-time profiles of ethanol were determined for venous whole blood and end-expired breath during a controlled drinking experiment in which healthy men (n=9) and women (n=9) drank 0.40-0.65 g ethanol per kg body weight in 20-30 min. Specimens of blood and breath were obtained for analysis of ethanol starting at 50-60 min post-dosing and then every 30-60 min for 3-6 h. This protocol furnished 130 blood-breath pairs for statistical evaluation. Blood-ethanol concentration (BAC, mg/g) was determined by headspace gas chromatography and breath-ethanol concentration (BrAC, mg/2l) was determined with a quantitative infrared analyzer (Intoxilyzer 5000S), which is the instrument currently used in Sweden for legal purposes. In 18 instances the Intoxilyzer 5000S gave readings of 0.00 mg/2l whereas the actual BAC was 0.08 mg/g on average (range 0.04-0.15 mg/g). The remaining 112 blood- and breath-alcohol measurements were highly correlated (r=0.97) and the regression relationship was BAC=0.10+0.91BrAC and the residual standard deviation (S.D.) was 0.042 mg/g (8.4%). The slope (0.91+/-0.0217) differed significantly from unity being 9% low and the intercept (0.10+/-0.0101) deviated from zero (t=10.2, P<0.001), indicating the presence of both proportional and constant bias, respectively. The mean bias (BAC - BrAC) was 0.068 mg/g and the 95% limits of agreement were -0.021 and 0.156 mg/g. The average BAC/BrAC ratio was 2448+/-540 (+/-S.D.) with a median of 2351 and 2.5th and 97.5th percentiles of 1836 and 4082. We found no significant gender-related differences in BAC/BrAC ratios, being 2553+/-576 for men and 2417+/-494 for women (t=1.34, P>0.05). The mean rate of ethanol disappearance from blood was 0.157+/-0.021 mg/(g per hour), which was very close to the elimination rate from breath of 0.161+/-0.021 mg/(2l per hour) (P>0.05). Breath-test results obtained with Intoxilyzer 5000S (mg/2l) were generally less than the coexisting concentrations of ethanol in venous blood (mg/g), which gives an advantage to the suspect who provides breath compared with blood in cases close to a threshold alcohol limit.     

A fatal case of pure ethanol ingestion

An adult male was found dead in a car with two empty bottles (500 ml x 2) labeled dehydrated ethanol (>99.5%, v/v). At autopsy, extensive pancreatic necrosis with severe hemorrhage was observed. High concentrations of ethanol were detected in blood (8.14 mg/ml), urine (8.12 mg/ml) and tissue specimens. The cause of death was determined to be an acute alcohol intoxication caused by ingesting approximately 1l dehydrated ethanol.     

Bupropion and alcohol fatal intoxication: case report.

A fatality due to the ingestion of bupropion and ethanol is presented. Bupropion and its metabolites were extracted from several tissues and identified using gas chromatography with nitrogenphosphorus and mass spectrometry detection. The concentrations of bupropion, hydroxybupropion and the erythroamino and threoamino alcohol metabolites in heart blood were 4.2, 5.0, 0.6 and 4.6 mg/l, respectively. The heart blood ethanol concentration was 0.27 g/dl. In addition, bupropion was distributed as follows: subclavian blood, 6.2 mg/l; bile, 1.4 mg/l; kidney, 2.4 mg/l; liver, 1.0 mg/kg; stomach contents, 16 mg and urine, 37 mg/l.