Terhi Launiainen

Comparison of fatal poisonings by prescription opioids

There is a rising trend of fatal poisonings due to medicinal opioids in several countries. The present study evaluates the drug and alcohol findings as well as the cause and manner of death in opioid-related post-mortem cases in Finland from 2000 to 2008. During this period, fatal poisonings by prescription opioids (buprenorphine, codeine, dextropropoxyphene, fentanyl, methadone, oxycodone, tramadol) increased as a share of all drug poisonings from 9.5% to 32.4%, being 22.3% over the whole period. A detailed study including the most prevalent opioids was carried out for the age group of 14-44 years, which is the most susceptible age for drug abuse in Finland. Poisonings by the weak opioids, codeine and tramadol, were found to be associated with large, often suicidal overdoses resulting in high drug concentrations in blood. Methadone poisonings were associated with accidental overdoses with the drug concentration in blood remaining within a therapeutic range. The manner of death was accidental in 43%, 55% and 94% of cases in codeine, tramadol and methadone poisonings, respectively. The median concentration of codeine and the median codeine/morphine concentration ratio were higher in codeine poisonings (1.4 and 22.5 mg/l, respectively) than in other causes of death (0.09 and 5.9 mg/l, respectively). The median concentrations of tramadol and O-desmethyltramadol were higher in tramadol poisonings (5.3 and 0.8 mg/l, respectively) than in other causes of death (0.6 and 0.2 mg/l, respectively). In methadone poisonings, the median concentration of methadone (0.35 mg/l) was not different from that in other causes of death (0.30 mg/l). Sedative drugs and/or alcohol were very frequently found in fatal poisonings involving these prescription opioids.

Drug concentrations in post-mortem femoral blood compared with therapeutic concentrations in plasma.

Therapeutic drug concentrations measured in plasma are of limited value as reference intervals for interpretation in post-mortem (PM) toxicology. In this study, drug concentration distributions were studied in PM femoral venous blood from 57 903 Finnish autopsy cases representing all causes of death during an 11-year period. Cause-of-death information was obtained from death certificates issued by forensic pathologists. Median, mean, and upper percentile (90th, 95th, 97.5th) concentrations were calculated for 129 drugs. To illustrate how PM median concentrations relate to established therapeutic ranges in plasma, a PM blood/plasma relationship was calculated for each drug. Males represented 75% of the subjects and showed a lower median age (55 yrs) than females (59 yrs). In 43% of these cases, blood alcohol concentration was higher than 0.2‰, and the median was 1.8‰. Sixty-one (47%) of the 129 drugs showed a PM blood/plasma relationship of 1. For 22 drugs (17%), the relationship was <1, and for 46 drugs (35%), the relationship was >1. No marked correlation was found between the PM blood/plasma relationship and the volume of distribution (Vd). For 36 drugs, more than 10% of cases were fatal poisonings attributed to this drug as the main finding. These drug concentration distributions based on a large database provide a helpful reference not only to forensic toxicologists and pathologists but also to clinical pharmacologists in charge of interpreting drug concentrations in PM cases.

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 β1-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.

Effect of carboxylesterase 1 c.428G > A single nucleotide variation on the pharmacokinetics of quinapril and enalapril

AIM The aim of the present study was to investigate the effects of the carboxylesterase 1 (CES1) c.428G > A (p.G143E, rs71647871) single nucleotide variation (SNV) on the pharmacokinetics of quinapril and enalapril in a prospective genotype panel study in healthy volunteers. METHODS In a fixed-order crossover study, 10 healthy volunteers with the CES1 c.428G/A genotype and 12 with the c.428G/G genotype ingested a single 10 mg dose of quinapril and enalapril with a washout period of at least 1 week. Plasma concentrations of quinapril and quinaprilat were measured for up to 24 h and those of enalapril and enalaprilat for up to 48 h. Their excretion into the urine was measured from 0 h to 12 h. RESULTS The area under the plasma concentration-time curve from 0 h to infinity (AUC0-∞) of active enalaprilat was 20% lower in subjects with the CES1 c.428G/A genotype than in those with the c.428G/G genotype (95% confidence interval of geometric mean ratio 0.64, 1.00; P = 0.049). The amount of enalaprilat excreted into the urine was 35% smaller in subjects with the CES1 c.428G/A genotype than in those with the c.428G/G genotype (P = 0.044). The CES1 genotype had no significant effect on the enalaprilat to enalapril AUC0-∞ ratio or on any other pharmacokinetic or pharmacodynamic parameters of enalapril or enalaprilat. The CES1 genotype had no significant effect on the pharmacokinetic or pharmacodynamic parameters of quinapril. CONCLUSIONS The CES1 c.428G > A SNV decreased enalaprilat concentrations, probably by reducing the hydrolysis of enalapril, but had no observable effect on the pharmacokinetics of quinapril.

Meconium drug testing reveals maternal misuse of medicinal opioids among addicted mothers

Meconium drug testing is a non-invasive method to detect prenatal drug exposure, which can cause severe problems for the infant, indicating the need for follow-up measures to ensure the welfare of the child. Meconium samples for drug testing were collected from 143 infants as part of routine clinical work among addicted mothers. The drug testing findings were combined with medical records including clinical background and follow-up data. The substances screened for included medicinal opioids, 6-monoacetylmorphine (a metabolite of heroin), amphetamines and tetrahydrocannabinolic acid. At least one of the 13 target drugs was detected in 57 (40%) meconium samples. In 21 cases, the findings were unexpected on the basis of clinical data or denied by the mother. Medicinal opioids, especially the opioid substitution treatment drugs buprenorphine and methadone, comprised the majority of the findings of both admitted and unexpected drug misuse. Meconium drug testing methods should target not just traditional illicit drugs but also prescription drugs with misuse potential.