Carisoprodol intoxications: a retrospective study of forensic autopsy material from 1992–2003

Fatal toxicity index of medicinal drugs based on a comprehensive toxicology database

The fatal toxicity index (FTI) is the absolute number of fatal poisonings caused by a particular drug divided by its consumption figure. Consequently, it is a useful measure in evaluating toxicity of the drug and its relevance in fatal poisonings. In this study, we assessed the FTI of medicinal drugs in 3 years (2005, 2009, and 2013) in Finland. As the measure of drug consumption, we used the number of defined daily doses (DDD) per population in each year. There were 70 medicinal drugs in Finland for which the mean FTI expressed as the number of deaths per million DDD over the three study years was higher or equal to 0.1. The Anatomical Therapeutic Chemical (ATC) classification system was used for the classification of the active ingredients of medicinal drugs according to the organ or system which they act on. Of these 70 drugs, 55 drugs (78.6 %) acted on the nervous system (denoted by ATC code N), 11 (15.7 %) on the cardiovascular system (C), three (4.3 %) on the alimentary tract and metabolism (A), and one (1.4 %) on the musculoskeletal system (M). The nervous system drugs consisted of 20 psycholeptics, (ATC code N05), 20 psychoanaleptics (N06), eight analgesics (N02), six antiepileptics (N03), and one other nervous system drug (N07). The highest individual FTIs were associated with the opioids methadone, dextropropoxyphene, oxycodone, tramadol, and morphine; the antipsychotics levomepromazine and chlorprothixene; and the antidepressants doxepin, amitriptyline, trimipramine, and bupropion. Buprenorphine was not included in the study, because most of the fatal buprenorphine poisonings were due to smuggled tablets. A clearly increasing trend in FTI was observed with pregabalin and possibly with bupropion, both drugs emerging as abused substances.

The total sale of prescription drugs with an abuse potential predicts the number of excessive users: a national prescription database study

BACKGROUND

Prescription drug sales may vary considerably across regions and over time. This study aimed to assess whether there is an association between mean drug sales and prevalence of excessive use in a range of psychotropic prescription drugs with an abuse potential, and if so, whether the variation in mean drug sales mostly reflects variation in the prevalence of excessive use or mostly reflects variation in non-excessive use.

METHODS

Data on all filled prescriptions taken from the Norwegian prescription database for 10 drugs with an abuse potential (pain relievers, anxiolytics, and hypnotics) during one calendar year (2005) in Norway (n = 4,053,624) included number of defined daily doses (DDD). These were aggregated to individual level (n = 815,836) and county level (n = 19).

RESULTS

Analyses of individual level data showed that the distribution of drug use was skewed; those who used more than 365 DDD per year accounted for almost half of the sales of both anxiolytics and hypnotics. At the county level, the mean sales per inhabitant and the prevalence of excessive users were closely correlated, but both prevalence of non-excessive use and prevalence of excessive drug use were associated with the county-wise variation in mean drug sales.

CONCLUSION

Despite a strong individual control of access to psychotropic drugs through health personnel' prescribing, a small proportion of users account for a large fraction of the sales of these drugs. The sales vary significantly between regions and this variation is closely associated with the prevalence of excessive users. This suggests that sales figures as such may be used as an indicator to monitor variations in excessive use between regions and over time, and to evaluate interventions targeting over-prescription and excessive use.

Has Previous Abuse of Flunitrazepam Been Replaced by Clonazepam?

BACKGROUND AND AIMS

For many years, flunitrazepam was the benzodiazepine of choice among users of illegal drugs. The aim of this study was to investigate to which extent clonazepam use has increased in this population, and whether this was related to increased prescription or because of illegal availability.

METHODS

We used data from three sources to study the changes in the use of clonazepam: (1) Presence and concentrations of clonazepam and flunitrazepam in blood samples collected from Norwegian drugged drivers; (2) Sales numbers (legal market) for clonazepam, extracted from the Norwegian prescription database (NorPD), and (3) Specific seizures (illegal market) for clonazepam in Norway.

RESULTS

In 2004, 13.0% of the analysed blood samples from drugged drivers contained clonazepam, whereas this proportion had increased to 27.7% in 2013. In the same period, the frequency of flunitrazepam in drugged drivers decreased from 16.6% in 2004 to 3.2% in 2013. The number of clonazepam prescriptions decreased, while the number of seized tablets containing clonazepam increased considerably from 2004 to 2013.

CONCLUSIONS

For the last 10 years, a significant increase in the illegal use of clonazepam has been seen, now replacing flunitrazepam as the most used illegal benzodiazepine in Norway.

Change in access to prescribed medication following an episode of deliberate self-poisoning: a multilevel approach

Objective

Patients with a history of deliberate self-poisoning (DSP) are prescribed a greater amount of medication than the general public. DSP is the most robust risk factor for repeat episodes of DSP and subsequent death by suicide, and one might therefore expect that access to prescribed medication would be reduced following an episode of DSP. However, it is unclear whether access to prescribed medication changes after an episode of DSP. The objectives of this study were to investigate changes in 1) overall, psychotropic, non-psychotropic and the psychotropic subgroup antidepressant prescribed medication availability in DSP patients following an episode of DSP, 2) prescribing of the medication ingested in the episode, and 3) potential effects of gender, age and repeater status on such change.

Methods

The design was longitudinal. We included 171 patients admitted for DSP between January 2006 and March 2007. Data on patients' prescriptions prior to admission were retrieved from The Norwegian Prescription Database. The outcome measure was the difference between medication load in the year following compared to the year prior to the DSP episode.

Results

There was a significant increase in total medication load following DSP, including both psychotropic and non-psychotropic medication. Antidepressant medication load remained stable. There was a tendency for access to drugs ingested in the episode to increase following the episode, albeit not significantly. Medication load increased with age across all medication groups irrespective of time period and gender.

Conclusions

The findings show that physicians do not curb prescribing to patients who have recently deliberately self-poisoned. Moreover, they highlight the need for cautious and judicious prescribing for these patients, in combination with psychological and social interventions.

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.

Evaluation of the first immunoassay for the semi-quantitative measurement of meprobamate in human whole blood or plasma using biochip array technology

BACKGROUND

Meprobamate is a carbamate, and the main metabolite of carisoprodol. It is used as an anxiolytic agent. Overdose of both drugs produces intoxication that is often serious and sometimes life threatening. However there was until now no immunoassay for the diagnosis of this intoxication.

METHODS

A chemiluminescent immunoassay for the semi-quantitative measurement of meprobamate in human blood and plasma has recently been developed, using the Evidence Investigator system (Randox®). In this study, the immunoassay was evaluated by testing drug-free (n=10) or spiked whole blood and plasma samples (n=70), and authentic post mortem whole blood samples from deceased patients in which meprobamate was present (n=38) or not (n=10). A previously validated gas chromatography-mass spectrometry (GC-MS) method was used for confirmation and quantification. 97 psychoactive drugs including carisoprodol were analyzed for possible interference.

RESULTS

With a cut-off at 0.5 mg/L, specificity, sensitivity and accuracy were 100%, 97.2% and 97.6%, respectively. All the untreated patients presented results under the cut-off. Meprobamate was not detected in three whole blood samples spiked with concentrations under the therapeutic range. In the authentic patients (n=48), there were no false-negative results. A good correlation was found between the immunoassay and GC-MS (r=0.90). Quantitative results of the immunoassay are approximately two-fold lower than GC-MS results. Only carisoprodol presented a cross-reactivity, 38±6.6% at 10 mg/L, and 26±4.8% at 100mg/L.

CONCLUSION

The first meprobamate immunoassay has shown very good specificity, selectivity and accuracy, which allow its use in hospital clinical laboratories for rapid diagnosis of meprobamate (or carisoprodol) intoxications.

Prevalence of adverse drug combinations in a large post-mortem toxicology database

The prevalence of important adverse drug combinations was studied among the 37,367 cases included in the Finnish post-mortem toxicology database during 2000-2006. The new SFINX interaction database (Swedish, Finnish, INteraction X-referencing) was utilised to identify adverse drug combinations. Consequently, the 24 drugs chosen for the study generated 96 two-compound combinations possessing potentially severe interactions. The total number of hits for the combinations found in the post-mortem database was 267, which accounts for approximately 0.71% of all cases. The potential role of adverse drug interaction (ADI) in these cases was evaluated from the background information and death certificate. The possible ADI cases comprised 23% of all hits and 0.17% of all cases analysed. In cases with a pharmacodynamic mechanism, the most prominent combinations were medicines causing serotonin syndrome or a beta(1)-blocker with verapamil or diltiazem. In cases with a pharmacokinetic mechanism, half of the cases involved digoxin in combination with verapamil. In one third of the possible ADI cases, a forensic pathologist had noted the studied compounds as an underlying or contributing cause of death, although the agents' specific role in ADIs was rarely recognised.

Interpretation of drug concentrations in an alternative matrix: the case of meprobamate in bile

Investigating toxicological causes of death may require alternative matrices when the usual ones are lacking. Whereas forensic toxicology uses bile almost only for xenobiotic screening, a diagnostic test interpreting postmortem bile concentrations of meprobamate is reported. Based on 128 sets of autopsy data, its intrinsic qualities were good, with 0.95 sensitivity and 0.93 specificity. In a French forensic population, the positive and negative predictive factors were 0.90 and 0.97, respectively. It is a useful means of revealing overdoses where blood samples are not available or of confirming blood tests when postmortem redistribution is suspected.

The risk of traffic accidents after prescriptions of carisoprodol

OBJECTIVE

Carisoprodol, a drug used for acute lower back pain, may cause psychomotor impairment. We wanted to investigate if patients using carisoprodol had increased risk of being involved in a traffic accident.

METHODS

Data were retrieved from three population-based registries for the period April 2004-September 2005. The Norwegian Prescription Database contained individual information on all dispensed drugs at all pharmacies outside hospitals. The Norwegian Road Accident Registry contained information on all drivers involved in motor vehicle accidents with person injury. The Norwegian Central Population Registry was used to control for emigration or death. The accident incidence among carisoprodol exposed and unexposed subjects was compared by standardized incidence ratio.

RESULTS

Having a prescription for carisoprodol dispensed increased the standardized incidence ratio for being involved in an accident with person injury to 3.7 (95% CI 2.9-4.8) the first week after the date of dispensing. This was similar to diazepam (2.8; 2.2-3.6), but higher than for salbutamol (1.1; 0.6-1.8).

CONCLUSIONS

Patients receiving carisoprodol seem to have an increased risk of being involved in traffic accidents involving person injury. The study gives support to earlier work published on the impairing effects of carisoprodol.

Clotted blood as sign of alcohol intoxication: a retrospective study

A total of 138 autopsies performed at the Institute of Legal Medicine of the University of Münster between 1994 and 2006 were subdivided into two groups: (1) 69 asphyxial deaths with a blood alcohol level (BAL) > 1 per thousand and (2) 69 asphyxial deaths with a BAL of 0.00 per thousand. The coagulation state in the central vessels was registered in all cases as fluid, compactly clotted or loosely clotted, and the post-mortem interval was recorded. Histology investigations were performed on the liver to analyze the incidence of hepatic fibrosis/cirrhosis. Fisher's exact test was performed to check for statistical significance. The blood was found to be clotted in 49.3% of the cases of group (1) and in 5.8% of group (2) (p < 0.01). The post-mortem interval did not have any influence on the coagulation state as observed in both groups. Liver fibrosis/cirrhosis was a rare finding detected in three cases in group 1 and in two cases in the control group 2 and, therefore, not relative to our observations. A distinctly positive BAL is often associated with heavy stages of blood coagulation as observed during autopsy. Distinctly positive alcohol concentrations have an influence on the fibrinolytic process and, hence, on the coagulation status.

In vitro formation of ethanol in autopsy samples containing fluoride ions

We present a case of a death of a diabetic man where the concentration of ethanol in post-mortem blood rose from 0.4 g/l 2 days after autopsy to 3.5 g/l 10 days after autopsy. The presence of fluoride ions in this blood sample was determined with ion chromatography and verified that fluoride ions were added to the vials. The concentrations of free fluoride, corresponding to 0.21 and 0.25% w/v potassium fluoride in blood and urine, respectively, were somewhat lower than the recommended 1% w/v. However, the amount of fluoride ions bound to calcium, proteins and other compounds in the samples is unknown. The blood sample was also subject to microbiological examination, which revealed growth of bacteria. In addition, a very high concentration of glucose was found in vitreous humour from the deceased. To determine whether the ethanol detected at the first analysis was of ante-mortem origin, ethyl glucuronide was analysed. Its absence, in the blood as well as the urine sample, strongly supported the theory that, in this case, all the ethanol detected was formed post-mortem. This case showed that ethanol may be formed in vitro at a very high concentration, despite the verified presence of fluoride ions. Possible reasons for this unusual formation of ethanol were the abundant presence of bacteria, a high level of glucose and, possibly, an insufficient amount of fluoride added to the vials.