Fatal intoxication cases: cytochrome P 450 2D6 and 2C19 genotype distributions

Polypharmacy-related Shock Symptoms and Complications Associated with Phenothiazine

This report describes a case of shock symptoms in a 72-year-old woman with epilepsy who had been in a state of polypharmacy, taking multiple antipsychotic drugs. After receiving a normal dose of periciazine, she exhibited impaired consciousness, hypothermia, and hypotension and was admitted to hospital. Despite poor response to vasopressors, conservative treatment led to gradual improvement. Subsequent pharmacokinetic analysis showed non-toxic blood concentrations of periciazine, suggesting that even small doses of phenothiazines could result in toxic symptoms. This case highlights the importance of monitoring for adverse reactions when prescribing multiple antipsychotic drugs, particularly in older polypharmacy patients.

Oxycodone findings and CYP2D6 function in postmortem cases

Genetic disposition can cause variation in oxycodone pharmacokinetic characteristics and decrease or increase the expected clinical response. In forensic medicine, determination of cause of death or assessing time between drug intake and death can be facilitated by knowledge of parent and metabolite concentrations. In this study, the aim was to investigate if CYP2D6 genotyping can facilitate interpretation by investigating the frequency of the four CYP2D6 phenotypes, poor metabolizer, intermediate metabolizer, extensive metabolizer, and ultra-rapid metabolizer in postmortem cases, and to study if the CYP2D6 activity was associated with a certain cause of death, concentration, or metabolic ratio. Cases positive for oxycodone in femoral blood (n = 174) were genotyped by pyrosequencing for CYP2D6*3, *4, and *6 and concentrations of oxycodone, noroxycodone, oxymorphone, and noroxymorphone were determined by LC-MS/MS (LLOQ 0.005 µg/g). Digital droplet PCR was used to determine the copy number variation for CYP2D6*5. Cases were categorized by cause of death. It was found that poor and intermediate CYP2D6 metabolizers had significantly higher oxycodone and noroxycodone concentrations compared to extensive and ultra-rapid metabolizers. CYP2D6 phenotype were equally distributed between cause of death groups, showing that no phenotype was overrepresented in any of the cause of death groups. We also found that the concentration ratio between oxymorphone and oxycodone depended on the CYP2D6 activity when death was unrelated to intoxication. In general, a low metabolite to parent ratio indicate an acute intake. By using receiver operating characteristic (ROC) analysis, we conclude that an oxymorphone/oxycodone ratio lower than 0.075 has a high sensitivity for separating intoxications with oxycodone from other intoxications and non-intoxications. However, the phenotype needs to be known to reach a high specificity. Therefore, the ratio should not be used as a biomarker on its own to distinguish between different causes of death but needs to be complemented by genotyping.

Predicting CYP2D6 phenotype from resting brain perfusion images by gradient boosting

The cytochrome P450 enzyme 2D6 is involved in the metabolism of 20% of all commonly used drugs, including many psychotropic drugs and CNS-active substances. CYP2D6 is among the CYP enzymes with the highest expression levels in the brain, suggesting a role in the local brain metabolism of psychotropic drugs and the existence of endogenous substrates. The genetic polymorphism of CYP2D6, which causes individual differences in activity levels of the enzyme, has also been characterized functionally in human brain imaging studies. Here we explore the feasibility of predicting CYP2D6 phenotype using component-wise gradient boosting on fMRI resting brain perfusion images. The images belonged to subjects showing a range of genetic CYP2D6 variants. We achieved sensitivity and specificity values between 85% and 87% for the classification of ultrarapid metabolisers, and between 71% and 79% for poor metabolisers. An extension of the boosting algorithm, developed to improve the clinical plausibility of the inherently sparse models, produced enhanced models in agreement with the results of previous studies, showing some brain regions as positively associated with genotypic variation, most prominently in the prefrontal white matter and the corpus callosum. With further development, such a probabilistic method might constitute a valuable, non-invasive alternative to actual genotyping.

Is toxicity of PMMA (paramethoxymethamphetamine) associated with cytochrome P450 pharmacogenetics?

In 2010-2013, 29 fatal intoxications related to the designer drug paramethoxymethamphetamine (PMMA, 4-methoxymethamphetamine) occurred in Norway. The current knowledge about metabolism and toxicity of PMMA in humans is limited. Metabolism by the polymorphic cytochrome P450 (CYP) 2D6 enzyme to the psychoactive metabolite 4-hydroxymethamphetamine (OH-MA), and possibly by additional enzymes, is suggested to be involved in its toxicity. The aim of this work was to study the association between CYP genetics, PMMA metabolism and risk of fatal PMMA toxicity in humans. The frequency distribution of clinically relevant gene variants of CYP2D6, CYP2C9, CYP2C19 and CYP3A5, and the phenotypic blood CYP2D6 metabolic ratio (OH-MA/PMMA) in particular, were compared in fatal PMMA intoxications (n=17) and nonfatal PMMA abuse controls (n=30), using non-abusers (n=305) as references for the expected genotype frequencies in the Norwegian population. Our study demonstrated that the CYP2D6 enzyme and genotype are important in the metabolism of PMMA to OH-MA in humans, but that other enzymes are also involved in this biotransformation. In the fatal PMMA intoxications, the blood concentrations of PMMA were higher and the CYP2D6 metabolic ratios were lower, than in the nonfatal PMMA abuse controls (median (range) 2.1 (0.03-5.0) vs 0.3 (0.1-0.9) mg/L, and ratio 0.6 (0.0-4.6) vs 2.1 (0.2-7.4) p=0.021, respectively). Overall, our findings indicated that, in most cases, PMMA death occurred rapidly and at an early stage of PMMA metabolism, following the ingestion of large and toxic PMMA doses. We could not identify any genetic CYP2D6, CYP2C9, CYP2C19 or CYP3A5 predictive marker on fatal toxicity of PMMA in humans. The overrepresentation of the CYP2D6 poor metabolizer (PM) genotype found in the nonfatal PMMA abuse controls warrants further investigations.

Polymorphism in CYP2D6 and CYP2C19, members of the cytochrome P450 mixed-function oxidase system, in the metabolism of psychotropic drugs

Numerous studies in the field of psychopharmacological treatment have investigated the possible contribution of genetic variability between individuals to differences in drug efficacy and safety, motivated by the wide individual variation in treatment response. Genomewide analyses have been conducted in several large-scale studies on antidepressant drug response. However, no consistent findings have emerged from these studies. In a recent meta-analysis of genomewide data from the three studies capturing common variation for association with symptomatic improvement and remission revealed the absence of any strong genetic association and failed to replicate results of individual studies in the pooled data. However, there are good reasons to consider the possible importance of pharmacogenetic variants separately. These variants explain a large portion of the manifold variability in individual drug metabolism. More than 20 psychotropic drugs have now been relabelled by the FDA adding information on polymorphic drug metabolism and therapeutic recommendations. Furthermore, dose recommendations for polymorphisms in drug metabolizing enzymes, first and foremost CYP2D6 and CYP2C19, have been issued with the advice to reduce the dosage in poor metabolizers to 50% or less (in eight cases), or to choose an alternative treatment. Beside the well-described role in hepatic drug metabolism, these enzymes are also expressed in the brain and play a role in biotransformation of endogenous substrates. These polymorphisms may therefore modulate brain metabolism and affect the function of the neural substrates of cognition and emotion.

Pharmacogenetic aspects of tramadol pharmacokinetics and pharmacodynamics after a single oral dose

The major purpose of this study was to elucidate if genotyping can facilitate interpretations of tramadol (TRA) in forensic case work, with special regard to the estimation of the time of drug intake and drug related symptoms (DRS). The association between genetic polymorphisms in CYP2D6, OPRM1 and ABCB1 and pharmacokinetic and pharmacodynamic properties of TRA was studied. Nineteen healthy volunteers were randomized into two groups receiving a single dose of either 50 or 100mg of orally administrated TRA. Blood samples were collected prior to dosing and up to 72h after drug intake. The subjects were asked to report DRS during the experimental day. We found a positive correlation between the metabolic ratio of O-desmethyltramadol (ODT) to TRA and the time after drug intake for both CYP2D6 intermediate metabolizers and extensive metabolizers. For the only poor metabolizer with detectable ODT levels the metabolic ratio was almost constant. Significant associations were found between the area under the concentration-time curve (AUC) and three of the investigated ABCB1 single nucleotide polymorphisms for TRA, but not for ODT and only in the 50mg dosage group. There was great interindividual variation in DRS, some subjects exhibited no symptoms at all whereas one subject both fainted and vomited after a single therapeutic dose. However, no associations could be found between DRS and investigated polymorphisms. We conclude that the metabolic ratio of ODT/TRA may be used for estimation of the time of drug intake, but only when the CYP2D6 genotype is known and taken into consideration. The influence of genetic polymorphisms in ABCB1 and OPRM1 requires further study.

Genetic variability of drug-metabolizing enzymes: the dual impact on psychiatric therapy and regulation of brain function

Polymorphic drug-metabolizing enzymes (DMEs) are responsible for the metabolism of the majority of psychotropic drugs. By explaining a large portion of variability in individual drug metabolism, pharmacogenetics offers a diagnostic tool in the burgeoning era of personalized medicine. This review updates existing evidence on the influence of pharmacogenetic variants on drug exposure and discusses the rationale for genetic testing in the clinical context. Dose adjustments based on pharmacogenetic knowledge are the first step to translate pharmacogenetics into clinical practice. However, also clinical factors, such as the consequences on toxicity and therapeutic failure, must be considered to provide clinical recommendations and assess the cost-effectiveness of pharmacogenetic treatment strategies. DME polymorphisms are relevant not only for clinical pharmacology and practice but also for research in psychiatry and neuroscience. Several DMEs, above all the cytochrome P (CYP) enzymes, are expressed in the brain, where they may contribute to the local biochemical homeostasis. Of particular interest is the possibility of DMEs playing a physiological role through their action on endogenous substrates, which may underlie the reported associations between genetic polymorphisms and cognitive function, personality and vulnerability to mental disorders. Neuroimaging studies have recently presented evidence of an effect of the CYP2D6 polymorphism on basic brain function. This review summarizes evidence on the effect of DME polymorphisms on brain function that adds to the well-known effects of DME polymorphisms on pharmacokinetics in explaining the range of phenotypes that are relevant to psychiatric practice.

CYP2C19 genetics in fatal carisoprodol intoxications

INTRODUCTION

Carisoprodol, a frequently used muscle relaxant, can cause potentially fatal intoxications. Conversion to its active metabolite meprobamate is almost solely mediated by cytochrome P450 2C19 (CYP2C19), and mutations in this enzyme could have significant effects on serum concentrations. The objective of this study was to investigate the role of CYP2C19 genetics in mortalities due to carisoprodol intoxication.

METHODS

The frequencies of CYP2C19 variant alleles were compared between the study group (n = 75) and two control groups, i.e. (1) deaths where carisoprodol was detected in the blood of the deceased, but intoxication was not the cause of death (control group A, n = 38), and (2) a healthy population not using carisoprodol (control group B, n = 185). In the study group and control A, the concentrations of carisoprodol and meprobamate were compared between the different genotype subgroups.

RESULTS

The variant allele frequencies of CYP2C19 did not differ significantly between the study group and control groups. Moreover, no statistically significant difference in the concentrations of carisoprodol and meprobamate between the different genotype subgroups was found.

CONCLUSIONS

This study finds no evidence for an important association between CYP2C19 genetics and mortality risk of carisoprodol. Other factors, such as co-administration with other drugs, likely play a more important role.

Toxicogenetics--cytochrome P450 microarray analysis in forensic cases focusing on morphine/codeine and diazepam

Genetic polymorphisms in cytochrome P 450 (CYP) enzymes could lead to a phenotype with altered enzyme activity. In pharmacotherapy, genotype-based dose recommendations achieved great importance for several drugs. In our pilot study, we ask if these genetic tests should be applied to forensic problems as a matter of routine. Starting from 2004 through 2008, we screened routine cases for samples where the relation of parent compound to metabolite(s) (P/M ratio), particularly morphine to codeine ratios and diazepam to its metabolites, was noticeable or not consistent with the information provided by the defendants. We found 11 samples with conspicuous results. These were analyzed for polymorphisms of the CYP 2D6 and 2C19 genes using the Roche AmpliChip Cytochrome P450 Genotyping test. If not previously conducted, a general unknown analysis by gas chromatography/mass spectrometry (GC/MS) was additionally carried out. For CYP 2D6, we found two cases with the genotype poor metabolizer (PM), three cases with heterozygote extensive metabolizer genotype classified as an intermediate metabolizer (IM) with probably reduced enzyme activities, but no ultrarapid metabolizer genotype. For CYP 2C19, two cases were characterized as IM phenotypes, with no PM found. Once we achieved no appropriate amounts of DNA, one case was excluded after GC/MS analysis. Only in one case could the polymorphism clearly explain the changes in drug metabolism. More frequently, a drug-drug interaction was thought to have a stronger impact. Additionally, our results suggest that IM genotypes may be more relevant than previously suspected. With respect to the small number of cases in which we thought a genotyping would be helpful, we conclude that the overall relevance of toxicogenetics in forensic problems is moderate. However, in some individual cases, a genotyping may provide new insight.

Usefulness of postmortem biochemistry in forensic pathology: illustrative case reports

The aim of this work is to present some practical, postmortem biochemistry applications to illustrate the usefulness of this discipline and reassert the importance of carrying out biochemical investigations as an integral part of the autopsy process. Five case reports are presented pertaining to diabetic ketoacidosis in an adult who was not known to suffer from diabetes and in presence of multiple psychotropic substances; fatal flecainide intoxication in a poor metabolizer also presenting an impaired renal function; diabetic ketoacidosis showing severe postmortem changes; primary aldosteronism presented with intracranial hemorrhage and hypothermia showing severe postmortem changes. The cases herein presented can be considered representative examples of the importance of postmortem biochemistry investigations, which may provide significant information useful in determining the cause of death in routine forensic casework or contribute to understanding the pathophysiological mechanisms involved in the death process.

Population differences in major functional polymorphisms of pharmacokinetics/pharmacodynamics-related genes in Eastern Asians and Europeans: implications in the clinical trials for novel drug development

Drug lag, recently discussed extensively in Japan, can be divided into two phases: clinical development time and application review time. The former factor is still an important problem that might be improved by promoting multi-regional clinical trials and considering the results from other similar populations with Japanese, such as Koreans and Chinese. In this review, we compare the allelic or genotype frequencies of 30 relatively common functional alleles mainly between Eastern Asians and Europeans as well as among 3 major populations in Eastern Asian countries, Japan, Korea, and China, in 12 pharmacokinetics (PK)/pharmacodynamics (PD)-related genes; CYP2C9 (*2 and *3), CYP2C19 (*2, *3 and *17), 13 CYP2D6 haplotypes including *4, *5 and *10, CYP3A5 (*3), UGT1A1 (*28 and *6), NAT2 (*5, *6 and *7), GSTM1 and GSTT1 null genotypes, SLCO1B1 521T>C, ABCG2 421C>A, and HLA-A*31:01 and HLA-B*58:01. In this review, differences in allele frequencies (AFs) or genotype frequencies (GFs) less than 0.1 (in the cases of highest AF (GF) ≥0.1) or less than 0.05 (in the cases of lowest AF (GF) <0.1) were regarded as similar. Between Eastern Asians and Europeans, AFs (or GFs) are regarded as being different for many alleles such as CYP2C9 (*2), CYP2C19 (*2, *3 and *17), CYP2D6 (*4 and *10), CYP3A5 (*3), UGT1A1 (*28 and *6), NAT2 (*5*7), GSTT1 null and ABCG2 421C>A. Among the 3 Eastern Asian populations, however, only AFs of CYP2C19*3, CYP2D6*10, HLA-A*31:01 and HLA-B*58:01 are regarded as dissimilar. For CYP2C19*3, the total functional impact on CYP2C19 could be small if the frequencies of the two null alleles CYP2C19*2 and *3 are combined. Regarding CYP2D6*10, frequency difference over 0.1 is observed only between Japanese and Chinese (0.147). Although environmental factors should be considered for PK/PD differences, we could propose that among Japan, Korea, and China, genetic differences are very small for the analyzed common PK-related gene polymorphisms. On the other hand, AFs of the two HLA alleles important for cutaneous adverse drug reactions are diverse even among Eastern Asians and thus should be taken into account.

Risk assessment of accidental nortriptyline poisoning: the importance of cytochrome P450 for nortriptyline elimination investigated using a population-based pharmacokinetic simulator

It is not possible to make a prospective clinical study that reveals the importance of the nortriptyline metabolising cytochrome P450 (CYP) isoforms (CYP1A2, CYP2C19, CYP2D6, and CYP3A4) in relation to attaining potential toxic nortriptyline concentrations with a possibly fatal outcome. Therefore to study this we have applied the population based pharmacokinetic simulator Simcyp. The objective was to estimate how important CYP2C19 and CYP2D6 phenotype status, hepatic activity of CYP3A4, body weight, CYP2D6 phenotype dose adjustment, and drug-drug interactions are with regard to accidental poisoning in a virtual population receiving a daily dose of 100mg nortriptyline. Accidental poisoning is here defined as intake of a normal dose which because of slow metabolism may lead to potentially toxic concentrations. The input parameters values for Simcyp were based on average literature in vitro and in vivo data. The Simcyp simulations of nortriptyline pharmacokinetics reflected reported clinical concentration-time profiles, therapeutic drug monitoring data, and the consequence of CYP2D6 poor metaboliser (PM) and ultrarapid metaboliser status. Of the investigated factors, the simulations indicate that having CYP2D6 PM status is a major risk factor for attaining high concentrations and thereby possibly becoming poisoned by nortriptyline. Of the CYP2D6 PM subjects 16% would attain plasma concentrations exceeding the toxic limit. Individuals with the combination of CYP2D6 PM status and 10% of the average liver CYP3A4 expression had a 90% risk of becoming poisoned. The results point towards the combination of low CYP3A4 activity and CYP2D6 PM status of major importance for attaining possibly toxic nortriptyline concentrations. In a forensic toxicological context, the results indicate that both the activity of CYP3A4, information on possible drug-drug interactions, and the genotype of CYP2D6 are needed in order to elucidate whether an individual might have been accidentally poisoned because of slow metabolism. In a clinical context, the simulations suggest that precise individual dose adjustment of nortriptyline requires information regarding the activity of both CYP3A4 and CYP2D6. This underlines the value of therapeutic drug monitoring for nortriptyline. Population based pharmacokinetic simulations are considered useful tools for risk assessment in clinical and forensic toxicology.

Antidepressant-induced akathisia-related homicides associated with diminishing mutations in metabolizing genes of the CYP450 family

PURPOSE

To examine the relation between variant alleles in 3 CYP450 genes (CYP2D6, CYP2C9 and CYP2C19), interacting drugs and akathisia in subjects referred to a forensic psychiatry practice in Sydney, Australia.

PATIENTS AND METHODS

This paper concerns 10/129 subjects who had been referred to the first author's practice for expert opinion or treatment. More than 120 subjects were diagnosed with akathisia/serotonin toxicity after taking psychiatric medication that had been prescribed for psychosocial distress. They were tested for variant alleles in CYP450 genes, which play a major role in Phase I metabolism of all antidepressant and many other medications. Eight had committed homicide and many more became extremely violent while on antidepressants. Ten representative case histories involving serious violence are presented in detail.

RESULTS

Variant CYP450 allele frequencies were higher in akathisia subjects compared with random primary care patients tested at the same facility. Ten subjects described in detail had variant alleles for one or more of their tested CYP450 genes. All but two were also on interacting drugs, herbals or illicit substances, impairing metabolism further. All those described were able to stop taking antidepressants and return to their previously normal personalities.

CONCLUSION

THE PERSONAL, MEDICAL, AND LEGAL PROBLEMS ARISING FROM OVERUSE OF ANTIDEPRESSANT MEDICATIONS AND RESULTING TOXICITY RAISE THE QUESTION: how can such toxicity events be understood and prevented? The authors suggest that the key lies in understanding the interplay between the subject's CYP450 genotype, substrate drugs and doses, co-prescribed inhibitors and inducers and the age of the subject. The results presented here concerning a sample of persons given antidepressants for psychosocial distress demonstrate the extent to which the psychopharmacology industry has expanded its influence beyond its ability to cure. The roles of both regulatory agencies and drug safety "pharmacovigilantes" in ensuring quality and transparency of industry information is highlighted.

Pharmacogenetics in medico-legal context

Medico-legal autopsy is the primary method in determining the cause and manner of death when the death is suspected to be unnatural. In some of these autopsies, the death remains ambiguous, even after a complete autopsy including histological investigation and toxicological screenings. In cases where there are no morphological abnormalities, medico-legal genetics may offer additional means to provide knowledge of possible genetic mutations, which may have initiated the process or predisposed the individual to stress risk conditions leading to death. One class of ambiguous deaths consists of drug-related deaths where the interpretation of the toxicological results are not clear. In such situations post mortem genotyping and the analysis of metabolite rations may provide an insight to the findings. A few cases demonstrating the potential strength of pharmacogenetics in medico-legal context has been published. However, there is a paramount need for serious scientific studies before the field of post mortem pharmacogenetics can be utilized in routine medico-legal analyses casework and brought routinely into courtroom.

Drug poisoning deaths in Sweden show a predominance of ethanol in mono-intoxications, adverse drug-alcohol interactions and poly-drug use

Over a 10-year period (1998-2007) all deaths in Sweden classified by forensic pathologists as fatal drug poisonings (N = 6894) were retrieved from a toxicology database (TOXBASE) belonging to the National Board of Forensic Medicine. The deaths were further classified as suicides N = 2288 (33%), undetermined N = 2260 (33%) and accidental N = 2346 (34%). The average age (± SD) of all victims was 49.1 ± 15.9 years and men 47.4 ± 15.6 years were 5-year younger than women 52.2 ± 15.8 years (p < 0.01). Most of the deceased (78%) were poly-drug users although a single drug (mono-intoxications) was found in 22% of all poisoning deaths (p < 0.001). The number of drugs in blood samples varied from 1 to 12 with a median of 3-4 per case. Mono-intoxication deaths were mostly ethanol-related (N = 976) and the mean and median blood-alcohol concentration (BAC) was 3.06 g/L and 3.10 g/L, respectively. The BAC decreased as the number of additional drugs in blood increased from 2.15 g/L with one drug to 1.25 g/L with 6 or more drugs. The mean (median) concentrations of non-alcohol drugs in mono-intoxication deaths were morphine (N = 93) 0.5mg/L (0.2mg/L), amphetamine (N = 39) 2.0mg/L (1.2mg/L), dextropropoxyphene (N = 33) 3.9 mg/L (2.9 mg/L), dihydro-propiomazine (N = 32) 1.6 mg/L (1.0mg/L) and 7-amino-flunitrazepam (N = 28), 0.4 mg/L (0.3mg/L). Elevated blood morphine in these poisoning deaths mostly reflected abuse of heroin as verified by finding 6-monoacetyl morphine (6-MAM) in the blood samples. When investigating drug poisoning deaths a comprehensive toxicological analysis is essential although the results do not reveal the extent of prior exposure to drugs or the development of pharmacological tolerance. The concentrations of drugs determined in post-mortem blood are one element in the case. The autopsy report, the police investigation, the findings at the scene and eye-witness statements should all be carefully considered when the cause and manner of death are determined.

High frequency of occurrence of CYP2D6 gene duplication/multiduplication indicating ultrarapid metabolism among suicide cases

In Sweden, about 550 individuals die every year of drug intoxication. Many of these drugs are metabolized by CYP enzymes such as CYP2D6 and CYP2C19. A lack of these enzymes, resulting in poor metabolism, can lead to adverse reactions and even to fatality. On the other hand, an ultrarapid metabolism can lead to insufficient drug plasma concentration, resulting in failure of treatment, or it can lead to high concentrations of active/toxic metabolites. The aim of this project was to study the genetic profile of individuals with regard to the presence of CYP2D6 and CYP2C19 genes, in cases of fatal intoxication (242), suicide (intoxications excluded) (262), and natural death (212). PCR, followed by pyrosequencing, was used for all the analyses. We found that, among those who died of suicide (suicide cases), there was a higher number carrying more than two active CYP2D6 genes (corresponding to the phenotype of ultrarapid metabolizer) as compared with those who died of natural causes (natural-death cases) (P = 0.007).

Estimating the Danish populations' preferences for pharmacogenetic testing using a discrete choice experiment. The case of treating depression

OBJECTIVE

The objective is to estimate willingness-to-pay (WTP) for pharmacogenetic testing in the treatment of depression.

METHODS

In a web-based discrete choice questionnaire, four attributes were included: 1) number of changes in antidepressants before symptom relief; 2) time with dosage adjustments due to adverse side effects and/or lack of effects; 3) cost of pharmacogenetic testing; 4) probability of benefits from pharmacogenetic testing. Respondents were asked to choose between two scenarios; 1) pharmacogenetic testing; and 2) an opt-out option reflecting a scenario without pharmacogenetic testing. The indirect utility model was assumed to be multiplicative in probability of benefits and reduced time with dosage adjustments as well as reduced number of antidepressant changes.

RESULTS

Most coefficients had the expected signs and were statistically significant. WTP for avoidance of one change in antidepressant medication is 1571 Danish Krone (DKK), whereas WTP for reducing the period with dosage-adjustments by 1 month is DKK604. Both were statistically significantly different from zero.

CONCLUSION

If diagnosed with depression, peoples' WTP for pharmacogenetic testing appears to exceed its price as long as there is a reasonable probability for improvements in treatment (in the present case 10%). Utility is associated with outcomes only. Hence, other modes of provision of similar improvements in treatment may be valued equally highly. WTP estimates and the associated policy implications appear to be robust because they were unaffected by estimation model.

EJCP and clinical toxicology: the first 40 years

INTRODUCTION

The European Journal of Clinical Pharmacology is now 40 years old and its history and development parallel developments in the related discipline of clinical (medical) toxicology. The journal has published many papers over its history that have informed its readers of scientific advances that link clinical pharmacology and clinical toxicology.

DISCUSSION

This review will provide an overview of the developments in treatment of poisoning and how effects of poisoning may provide information for drug regulation and suggests ways in which developments in pharmacogenetics and metabolomics may stimulate future research in this area.

SIMULTANEOUS GENOTYPING OF CYP2D6*3, *4, *5 AND *6 POLYMORPHISMS IN A SPANISH POPULATION THROUGH MULTIPLEX LONG POLYMERASE CHAIN REACTION AND MINISEQUENCING MULTIPLEX SINGLE BASE EXTENSION ANALYSIS

1. The aim of the present study was to perform a descriptive study of the prevalence of the four major CYP2D6 poor metaboliser (PM) alleles (*3, *4, *5 and *6) in a Spanish population (n = 290) using a method based on a new combination of multiplex long polymerase chain reaction (PCR) and minisequencing through multiplex single base extension (SBE) analysis. 2. The method was validated using different strategies, such as allelic discrimination assay and PCR-restriction fragment length polymorphism (RFLP). 3. The allele frequencies were similar to those described for other Spanish populations, namely 0.9% (95% confidence interval (CI) 0.5-1.3), 16.4% (95% CI 14.9-18.0), 2.7% (95% CI 2.0-3.4) and 0.7% (95% CI 0.3-1.0) for the *3, *4, *5 and *6 alleles, respectively. The results were satisfactory and left little doubt as to the genotypes, which were confirmed either by allelic discrimination assay (*4 and *6) or PCR-RFLP (*3) with 100% concordance. 4. The present study corroborates the low prevalence of the most frequent polymorphism (CYP2D6*4) that leads to null CYP2D6 activity in Spain and the allelic geographical gradient between Caucasian populations in the north and south. The present study reports a technique for the detection of four polymorphisms that account for 98% of the CYP2D6 defect alleles. This multiplex long PCR-SBE technique is a combination of several known methods to genotype CYP2D6 alleles (*3, *4, *5 and*6). Given the importance of CYP2D6 in drug metabolism and the need to genotype a large number of samples, we believe that this method will find broad application.

CYP2C19 polymorphism in Korean patients on warfarin therapy

This study was designed to assess the effect of CYP2C19 polymorphism on warfarin dosage requirements and bleeding complications in the Korean population. Patients were placed into one of four groups according to the dose of warfarin they received and the presence of bleeding complications: regular dose control, regular dose bleeding, low dose control, and low dose bleeding. Genotyping for CYP2C19*2 and CYP2C19*3 was performed by the restriction fragment length polymorphism method for each patient and each study group. The measured internal normalized ratio (INR) in each dose group was similar even though the administered dosage was significantly different. A total of 66 patients were evaluated for CYP2C19 polymorphism. Among them 25 patients (37.9%) were homozygous wild type. Four patients (6.1%) had heterozygous mutations at both loci. Others had mutations on either the CYP2C19*2 or *3 locus. Higher genetic variation was observed in CYP2C19*2 than in CYP2C19*3 among Korean patients on warfarin therapy. Our data suggested that there is a higher incidence of bleeding complications in patients who have a higher allele frequency of CYP2C19. It was also revealed that the distribution of CYP2C19 polymorphism among Asian populations is more similar than of the distribution among Caucasian populations.

CYP2D6 and CYP2C19 genotypes and amitriptyline metabolite ratios in a series of medicolegal autopsies

In a series of 202 postmortem toxicology cases, the CYP2D6 and CYP2C19 genes were genotyped, and the concentrations of amitriptyline (AT) and six metabolites were analyzed. The polymorphic CYP2D6 and CYP2C19 genes encode enzymes participating in the metabolism of several potentially toxic drugs, and mutations in these genes may lead to adverse drug reactions, possibly even intoxications. AT was chosen as the substrate of interest because it is mainly metabolized by these enzymes, is considered relatively toxic, and ranks among the major causes of fatal drug poisoning in Finland. Our objective was to evaluate genetically determined interindividual variation in conjunction with metabolite ratios of drugs found in toxicological analysis in a series of medicolegal autopsies. Positive correlations were found between the proportion of trans-hydroxylated metabolites and the number of functional copies of CYP2D6 and between the proportion of demethylated metabolites and the number of functional copies of CYP2C19. None of the accidental or undetermined AT poisonings coincided with the CYP2D6 or CYP2C19 genotype which predicts a poor metabolizer phenotype. However, an unusually high femoral blood concentration of AT, 60mg/l, was found in one suicide case with no functional CYP2D6 genes. Our study shows a concordance of AT metabolite patterns with CYP2D6 and CYP2C19 genotypes in the presence of confounding factors typical for postmortem material. This result demonstrates the feasibility of postmortem pharmacogenetic analysis and supports the dominant role of genes in drug metabolism.