Tissue distribution of mirtazapine and desmethylmirtazapine in a case of mirtazapine poisoning

Drugs, Metabolites, and Lung Accumulating Small Lysosomotropic Molecules: Multiple Targeting Impedes SARS-CoV-2 Infection and Progress to COVID-19

Lysosomotropism is a biological characteristic of small molecules, independently present of their intrinsic pharmacological effects. Lysosomotropic compounds, in general, affect various targets, such as lipid second messengers originating from lysosomal enzymes promoting endothelial stress response in systemic inflammation; inflammatory messengers, such as IL-6; and cathepsin L-dependent viral entry into host cells. This heterogeneous group of drugs and active metabolites comprise various promising candidates with more favorable drug profiles than initially considered (hydroxy) chloroquine in prophylaxis and treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections/Coronavirus disease 2019 (COVID-19) and cytokine release syndrome (CRS) triggered by bacterial or viral infections. In this hypothesis, we discuss the possible relationships among lysosomotropism, enrichment in lysosomes of pulmonary tissue, SARS-CoV-2 infection, and transition to COVID-19. Moreover, we deduce further suitable approved drugs and active metabolites based with a more favorable drug profile on rational eligibility criteria, including readily available over-the-counter (OTC) drugs. Benefits to patients already receiving lysosomotropic drugs for other pre-existing conditions underline their vital clinical relevance in the current SARS-CoV2/COVID-19 pandemic.

Determination of Antidepressants in Human Plasma by Modified Cloud-Point Extraction Coupled with Mass Spectrometry

Cloud-point extraction (CPE) is rarely combined with liquid chromatography coupled to mass spectrometry (LC-MS) in drug determination due to the matrix effect (ME). However, we have recently shown that ME is not a limiting factor in CPE. Low extraction efficiency may be improved by salt addition, but none of the salts used in CPE are suitable for LC-MS. It is the first time that the influences of a volatile salt-ammonium acetate (AA)-on the CPE extraction efficiency and ME have been studied. Our modification of CPE included also the use of ethanol instead of acetonitrile to reduce the sample viscosity and make the method more environmentally friendly. We developed and validated CPE-LC-MS for the simultaneous determination of 21 antidepressants in plasma that can be useful for clinical and forensic toxicology. The selected parameters included Triton X-114 concentration (1.5 and 6%, w/v), concentration of AA (0, 10, 20 and 30%, w/v), and pH (3.5, 6.8 and 10.2). The addition of 10% of AA increased recovery twice. For 20 and 30% (w/v) of AA, three phases were formed that prolonged the extraction process. The developed CPE method (6% Triton X-114, 10% AA, pH 10.2) was successfully validated through LC-MS/MS simultaneous determination of 21 antidepressants in human plasma. The linearity was in the range of 10-750 ng/mL (r2 > 0.990).

Reference Brain/Blood Concentrations of Citalopram, Duloxetine, Mirtazapine and Sertraline

Postmortem blood samples may not accurately reflect antemortem drug concentrations, as the levels of some drugs increase due to postmortem redistribution (PMR). The brain has been suggested as an alternative sampling site. The anatomically secluded site of the brain limits redistribution and prolongs the detection window, thereby enabling sampling from deceased individuals where blood is no longer suitable for analysis. We report concentrations in brain tissue and blood from 91 cases for the four antidepressants citalopram, duloxetine, mirtazapine and sertraline. The cases were classified according to their role in the cause of death, as follows: (A) concentrations where the drug was the sole cause of fatal intoxication; (B) concentrations where the drug contributed to a fatal outcome; and (C) concentrations where the drug was not related to the cause of death. The analytical method was successfully validated in brain tissue in terms of linearity, process efficiency, precision and accuracy. Quantification of analytes was performed by ultra-performance liquid chromatography with tandem mass spectrometry. Correlations between blood and brain concentrations were achieved with R2-values between 0.67 and 0.91. The following median brain-blood ratios were obtained: 3.71 for citalopram (range: 1.4-5.9), 11.0 for duloxetine (range: 5.0-21.6), 1.53 for mirtazapine (range: 1.02-4.71) and 7.38 for sertraline (range: 3.2-14.2). The S/R ratio of racemic citalopram was the same in brain (0.80) and blood (0.85), whereas the median citalopram/N-desmethylcitalopram ratio was higher in brain (9.1) than blood (4.1). The results of this study may serve as reference concentrations in brain for forensic cases.

High Prevalence of Psychotropics Overdose among Suicide Attempters in Korea

Objective

The availability of suicide methods affects the risk of suicide attempts. This study examined the patterns of substances ingested by suicide attempters (SAs) and the characteristics of SAs using psychotropic overdoses.

Methods

Data for 384 of the 462 eligible SAs who used self-poisoning were analyzed. Demographic variables, clinical characteristics, and factors related to the suicide attempts were examined.

Results

There were 256 (66.7%) females and 128 (33.3%) males. Roughly half the SAs ingested psychotropics (n=179, 46.6%). Agricultural chemicals (n=84, 21.9%) were the second most frequently ingested substances, followed by analgesics (n=62, 16.1%), household products (n=27, 7.0%), and other prescribed medications (n=23, 6.0%). Among psychotropics, the most frequently overdosed drugs were sedative-hypnotics, including hypnotics (n=104) and benzodiazepines (n=78). SAs favored Z-drugs and alprazolam. When compared with SAs with non-psychotropic overdoses, significantly more SAs with psychotropic overdoses were female (76% vs. 58.5%, p<0.001) and had a psychiatric history (59.8% vs. 29.8%, p<0.001). They had significantly more previous suicide attempts (0.52±1.02 vs. 0.32±0.80, p<0.05) and lower risk (7.96±1.49 vs. 8.44±1.99, p<0.01) and medical severity (3.06±0.81 vs. 3.37±0.93, p<0.005) scores.

Conclusion

Psychotropic overdose, especially with sedative-hypnotics, was a major method in suicide attempts. It is important that psychiatric patients are carefully evaluated and monitored for suicidality when prescribing psychotropics.

Collection of biological samples in forensic toxicology

Forensic toxicology is the study and practice of the application of toxicology to the purposes of the law. The relevance of any finding is determined, in the first instance, by the nature and integrity of the specimen(s) submitted for analysis. This means that there are several specific challenges to select and collect specimens for ante-mortem and post-mortem toxicology investigation. Post-mortem specimens may be numerous and can endow some special difficulties compared to clinical specimens, namely those resulting from autolytic and putrefactive changes. Storage stability is also an important issue to be considered during the pre-analytic phase, since its consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample. The knowledge on degradation mechanisms and methods to increase storage stability may enable the forensic toxicologist to circumvent possible difficulties. Therefore, advantages and limitations of specimen preservation procedures are thoroughfully discussed in this review. Presently, harmonized protocols for sampling in suspected intoxications would have obvious utility. In the present article an overview is given on sampling procedures for routinely collected specimens as well as on alternative specimens that may provide additional information on the route and timing of exposure to a specific xenobiotic. Last, but not least, a discussion on possible bias that can influence the interpretation of toxicological results is provided. This comprehensive review article is intented as a significant help for forensic toxicologists to accomplish their frequently overwhelming mission.

Development of a fast LC-MS/MS method for quantification of rilmenidine in human serum: elucidation of fragmentation pathways by HRMS

Rilmenidine is an alpha 2 adrenoreceptor agonist used in the treatment of mild and moderate hypertension. In this study, a fast and accurate liquid chromatographic method with tandem mass spectrometric detection has been validated in order to assure quantification of rilmenidine in human serum. The fragmentation pathway of protonated rilmenidine was studied using high-resolution mass spectrometry (HRMS). This study compared selectivity, linearity, accuracy, precision, extraction efficiency, matrix effect and sensitivity using common liquid-liquid extraction (LLE) and solid-phase extraction (SPE) procedures. The limit of quantitation for both extraction techniques was 0.1 ng/ml. Several differences between the LLE and SPE have been observed in terms of linearity, accuracy, precision and matrix effect. Additionally, the advantages of SPE included less manual work load and increased recovery of rilmenidine in human serum to approximately 80% (LLE, 57%). The developed method involving SPE was found to be accurate (relative error (RE) < 5%), reproducible (relative standard deviation, RSD < 7%), robust and suitable for quantitative analysis of rilmenidine in serum samples obtained from patients under antihypertensive treatment.

Genetic polymorphisms of CYP1A2, CYP3A4, CYP3A5, pregnane/steroid X receptor and constitutive androstane receptor in 207 healthy Spanish volunteers

BACKGROUND

Variability of cytochrome P450 (CYP) in humans is largely related to the pharmacological and toxicological effects of drugs and chemicals. Identification of single nucleotide polymorphisms (SNPs) could be important for knowing their involvement in many drugs metabolism. The goal of this study was to analyze the genotype frequency of 10 SNPs related to mirtazapine metabolism [CYP3A4*17, CYP3A4*18, CYP3A5*3A, CYP1A2*1F, pregnane/steroid X receptor (PXR) (rs3814055, rs38114057, rs3814058) and constitutive androstane receptor (CAR) (rs4073054, rs2307424, rs2502815)].

METHODS

The study was carried out in 207 healthy Spanish volunteers that had participated in phase I clinical trials. Other studies were performed: Hardy-Weinberg equilibrium, haplotype estimation and linkage disequilibrium.

RESULTS

No mutation related to CYP3A4*17 and CYP3A4*18 was found. Therefore, we analyzed data for the other eight SNPs. Allele frequencies were in equilibrium with the Hardy-Weinberg equation. Six haplotypes were determined for three PXR SNPs, and four for CAR SNPs. Tests for linkage disequilibrium showed a high association between PXR (rs38114057) and PXR (rs3814058) (p= 0.001), and between the three CAR SNPs (p=0.001), which could be useful for identification of tag SNPs.

CONCLUSIONS

In the present study, the genotype frequencies of some SNPs related to mirtazapine metabolism in Spaniards were analyzed and showed that our study population is representative of HapMap European population. The results obtained could be analyzed with pharmacokinetic parameters of mirtazapine to elucidate the genotype-phenotype relationship, the involvement of these SNPs in metabolic reactions, drug interactions, and prediction of treatment response.

Lack of significant toxicity after mirtazapine overdose: A five-year review of cases admitted to a regional toxicology unit

INTRODUCTION

Mirtazapine is a comparatively new antidepressant that selectively blocks central alpha2-adrenergic autoreceptors and postsynaptic 5-HT2 and 5-HT3 receptors, causing reduced neuronal norepinephrine and serotonin reuptake. The prevalence of mirtazapine prescribing has steadily risen; however, comparatively little information is available regarding the clinical features associated with mirtazapine overdose.

AIMS

To characterize the toxic features that result from mirtazapine overdose.

METHODS

We performed a retrospective case analysis of patients admitted to the Toxicology Unit of the Royal Infirmary of Edinburgh between January 2000 and December 2004 after stated mirtazapine overdose. Casenotes were examined for clinical, laboratory, and electrocardiographic safety data.

RESULTS

There were 117 mirtazapine cases where the median (interquartile range) stated dose ingested was 450 mg (240-785 mg). Conscious level was reduced in 27.2% of patients and there was a higher incidence of tachycardia (30.4%) than predicted from normal reference range values (p < 0.001). There was no evidence of any other significant clinical, laboratory, or electrocardiographic abnormality.

CONCLUSIONS

Severe toxic features could be attributed to other co-ingested drugs or alcohol. The adverse clinical effects attributable to mirtazapine overdose appeared mild and predictable. Mirtazapine overdose appears to be associated with fewer features of severe toxicity than previously reported for other antidepressants.

Fatal toxicity of drugs used in psychiatry

Certified deaths from fatal poisoning (accidents, suicides and open verdicts) in England and Wales have declined steadily (from 3952 in 1979 to 2565 in 2004). There was also a small annual reduction in suicides in males and in females over this period. In 2004, self-poisoning accounted for 25% of suicides and open verdicts in males (n = 862) and 45% in females (n = 540). Poisoning death rates per million prescriptions were about 10 times higher for tricyclic antidepressants (TCAs) than for selective serotonin reuptake inhibitors (SSRIs), England and Wales, 1993-2004. However, despite the increased prescription of SSRIs and related compounds in recent years, there has been only a slight decrease (some 10%) in the annual number of antidepressant-related poisoning deaths, in line with the reduction in suicides (all methods) over this period. Citalopram appears to have higher overdose toxicity than other SSRIs. Of newer non-SSRI antidepressants, the overdose toxicity of venlafaxine, although lower than that of TCAs, appears to be higher than that of SSRIs, with seizures, serotonin syndrome, rhabdomyolysis, renal failure and hepatic failure having been reported. Poisoning deaths involving antipsychotics either alone, or with other drugs and/or alcohol are many fewer than those involving antidepressants (713 and 5602 deaths, respectively, England and Wales, 1993-2004). Following the restriction on thioridazine usage (2000), thioridazine-associated fatal poisoning fell to zero by 2002, but this was balanced by an increase in deaths associated with atypical antipsychotics, most notably clozapine, olanzapine and quetiapine. Antipsychotic-related poisoning deaths were higher in 2004 than at any time since 1993.

An electrospray ionisation tandem mass spectrometric investigation of selected psychoactive pharmaceuticals and its application in drug and metabolite profiling by liquid chromatography/electrospray ionisation tandem mass spectrometry

A tandem mass spectrometric investigation of the collision-induced dissociation of five commonly prescribed psychoactive pharmaceuticals, risperidone, sertraline, paroxetine, trimipramine, and mirtazapine, and their metabolites has been carried out. Quadrupole ion trap mass spectrometry was employed to generate tandem mass spectrometric (MS/MS) data of the compounds under investigation and structural assignments of product ions were supported by quadrupole time-of-flight mass spectrometry. These fragmentation studies were then utilised in the development of a liquid chromatographic method to identify the drugs and their metabolites in human hair and saliva samples, thus providing relevant profiling information.