Morphine Accumulates in the Retina Following Chronic Systemic Administration

Opioid transport into the central nervous system is crucial for the analgesic efficacy of opioid drugs. Thus, the pharmacokinetics of opioid analgesics such as morphine have been extensively studied in systemic circulation and the brain. While opioid metabolites are routinely detected in the vitreous fluid of the eye during postmortem toxicological analyses, the pharmacokinetics of morphine within the retina of the eye remains largely unexplored. In this study, we measured morphine in mouse retina following systemic exposure. We showed that morphine deposits and persists in the retina long after levels have dropped in the serum. Moreover, we found that morphine concentrations (ng/mg tissue) in the retina exceeded brain morphine concentrations at all time points tested. Perhaps most intriguingly, these data indicate that following chronic systemic exposure, morphine accumulates in the retina, but not in the brain or serum. These results suggest that morphine can accumulate in the retina following chronic use, which could contribute to the deleterious effects of chronic opioid use on both image-forming and non-image-forming visual functions.

Alternative matrices in forensic toxicology: a critical review

Purpose

The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in providing additional information regarding drug exposure and analytical benefits. The goal of this paper is to present a critical review on the most recent literature regarding the application of six common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor in forensic toxicology.

Methods

The recent literature have been searched and reviewed for the characteristics, advantages and limitations of oral fluid, hair, sweat, meconium, breast milk and vitreous humor and its applications in the analysis of traditional drugs of abuse and novel psychoactive substances (NPS).

Results

This paper outlines the properties of six biological matrices that have been used in forensic analyses, as alternatives to whole blood and urine specimens. Each of this matrix has benefits in regards to sampling, extraction, detection window, typical drug levels and other aspects. However, theses matrices have also limitations such as limited incorporation of drugs (according to physical–chemical properties), impossibility to correlate the concentrations for effects, low levels of xenobiotics and ultimately the need for more sensitive analysis. For more traditional drugs of abuse (e.g., cocaine and amphetamines), there are already data available on the detection in alternative matrices. However, data on the determination of emerging drugs such as the NPS in alternative biological matrices are more limited.

Conclusions

Alternative biological fluids are important specimens in forensic toxicology. These matrices have been increasingly reported over the years, and this dynamic will probably continue in the future, especially considering their inherent advantages and the possibility to be used when blood or urine are unavailable. However, one should be aware that these matrices have limitations and particular properties, and the findings obtained from the analysis of these specimens may vary according to the type of matrix. As a potential perspective in forensic toxicology, the topic of alternative matrices will be continuously explored, especially emphasizing NPS.

Determination of morphine and its metabolites in the biological samples: an updated review

Morphine (MO) as an opioid analgesic is used for the treatment of moderate-to-severe pains, particularly cancer-related pains. Pharmacologic studies on MO are complicated due to drugs binding to the protein or metabolization to active metabolites, and even inter-individual variability. This necessitates the selection of a reliable analytical method for monitoring MO and the concentrations of its metabolites in the biological samples for the pharmacokinetic or pharmacodynamic investigations. Therefore, this study was conducted to review all the analytical research carried out on MO and its metabolites in the biological samples during 2007-2019 as an update to the study by Bosch et al. (2007).

Stability studies in biological fluids during post-analysis custody. Opiate compounds derived from heroin consumption

In Forensic Toxicology, the evidences have to be maintained under custody for, at least, one year. Depending on the conditions and duration of storage, drug concentrations might have changed considerably since the first analysis. The aim of this study is to evaluate in vitro stability of opiate compounds, derived from heroin consumption, 6-acetylmorphine (6-MAM), morphine (MOR) and codeine (COD), in blood and urine, during post-analysis custody. Parameters evaluated were: time of custody, temperature, addition of preservative (blood) and pH (urine). Blood and urine samples were spiked with the three analytes to give a final concentration of 1000 ng/mL. The prepared samples were divided into 2 groups and stored at two temperatures (4 °C and -20 °C). Each one of these groups was subsequently divided in other two groups: with and without preservative (1%NaF) for blood, and pH 4 and 8 in the case of urine. 6-MAM, MOR and COD were analyzed by GCMS after SPE and derivatization with BSTFA. Analyses were performed in triplicate every two weeks for a year. In blood samples 6-MAM is the only compound that degrades. The best storage conditions were at -20 °C with NaF, with 6-MAM recoveries, after one year of custody, of 47.1 ± 1.5%; while in the other conditions 6-MAM disappeared after 215 days (at 4 °C with NaF), 45 days (at -20 °C without NaF) and 15 days (at 4 °C without preservative). COD does not degrade, with recoveries higher than 90%, in all of the conditions. They ranged from 89.7 ± 3.6% in samples maintained at -20 °C without NaF to 95.9 ± 2.0% in those maintained at 4 °C with NaF. MOR recoveries were lower than those of COD. They ranged from 66.9 ± 3.6%, in frozen samples added with NaF, to 78.6 ± 0.5% in refrigerated samples without preservative. In urine samples the three compounds were stable in all the studied conditions, with the exception of 6-MAM in samples at pH 8 and stored at 4 °C. In these conditions, 6-MAM disappeared after 135 days of custody; while recoveries in the other conditions ranged from 93.7 ± 6.4%, at 4 °C and pH 4, to 85.1 ± 2.0% at -20 °C and pH 8. MOR and COD recoveries were similar in the four conditions. In the case of MOR, they ranged from 82.1 ± 1.2% at 4 °C and pH 4 to 89.5 ± 6.0% at -20 °C and pH 8. As far as COD is concerned, recoveries ranged from 111.6 ± 5.8% at 4 °C and pH 8 to 102.6 ± 1.2% at 4 °C and pH 4. In conclusion, the study showed that the most labile opiate compound is 6-MAM. Its stability mainly depends on urine pH or the addition of preservative, in blood samples. The best storage conditions for samples from heroin consumers are in the freezer, at -20 °C. In addition, blood samples must be added with 1%NaF and urine samples must be buffered at pH 4.

Rapid determination of designer benzodiazepines, benzodiazepines, and Z-hypnotics in whole blood using parallel artificial liquid membrane extraction and UHPLC-MS/MS

Benzodiazepines (BZD) and Z-hypnotics are frequently analyzed in forensic laboratories, and in 2012, the designer benzodiazepines (DBZD) emerged on the illegal drug scene. DBZD represent a particular challenge demanding new analytical methods. In this work, parallel artificial liquid membrane extraction (PALME) is used for sample preparation of DBZD, BZD, and Z-hypnotics in whole blood prior to UHPLC-MS/MS analysis. PALME of BZD, DBZD, and Z-hypnotics was performed from whole blood samples, and the analytes were extracted across a supported liquid membrane (SLM) and into an acceptor solution of dimethyl sulfoxide and 200 mM formic acid (75:25, v/v). The method was validated according to EMA guidelines. The method was linear throughout the calibration range (R² > 0.99). Intra- and inter-day accuracy and precision, as well as matrix effects, were within the guideline limit of ± 15%. LOD and LLOQ ranged from 0.10 to 5.0 ng mL^-1 and 3.2 to 160 ng mL^-1, respectively. Extraction recoveries were reproducible and above 52%. The method was specific, and the analytes were stable in the PALME extracts for 4 and 10 days at 10 and - 20 °C. No carry-over was observed within the calibration range. PALME and UHPLC-MS/MS for the determination of DBZD, BZD, and Z-hypnotics in whole blood are a green and low-cost alternative that provides high sample throughput (96-well format), extensive sample clean-up, good sensitivity, and high reproducibility. The presented method is also the first method incorporating analysis of DBZD, BZD, and Z-hypnotics in whole blood in one efficient analysis. Graphical abstract.

Vitreous humor analysis for the detection of xenobiotics in forensic toxicology: a review

Vitreous humor (VH) is a gelatinous substance contained in the posterior chamber of the eye, playing a mechanical role in the eyeball. It has been the subject of numerous studies in various forensic applications, primarily for the assessment of postmortem interval and for postmortem chemical analysis. Since most of the xenobiotics present in the bloodstream are detected in VH after crossing the selective blood-retinal barrier, VH is an alternative matrix useful for forensic toxicology. VH analysis offers particular advantages over other biological matrices: it is less prone to postmortem redistribution, is easy to collect, has relatively few interfering compounds for the analytical process, and shows sample stability over time after death. The present study is an overview of VH physiology, drug transport and elimination. Collection, storage, analytical techniques and interpretation of results from qualitative and quantitative points of view are dealt with. The distribution of xenobiotics in VH samples is thus discussed and illustrated by a table reporting the concentrations of 106 drugs from more than 300 case reports. For this purpose, a survey was conducted of publications found in the MEDLINE database from 1969 through April 30, 2015.

A validated method for simultaneous determination of codeine, codeine-6-glucuronide, norcodeine, morphine, morphine-3-glucuronide and morphine-6-glucuronide in post-mortem blood, vitreous fluid, muscle, fat and brain tissue by LC-MS

The toxicodynamics and, to a lesser degree, toxicokinetics of the widely used opiate codeine remain a matter of controversy. To address this issue, analytical methods capable of providing reliable quantification of codeine metabolites alongside codeine concentrations are required. This article presents a validated method for simultaneous determination of codeine, codeine metabolites codeine-6-glucuronide (C6G), norcodeine and morphine, and morphine metabolites morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in post-mortem whole blood, vitreous fluid, muscle, fat and brain tissue by high-performance liquid chromatography mass spectrometry. Samples were prepared by solid-phase extraction. The validated ranges were 1.5-300 ng/mL for codeine, norcodeine and morphine, and 23-4,600 ng/mL for C6G, M3G and M6G, with exceptions for norcodeine in muscle (3-300 ng/mL), morphine in muscle, fat and brain (3-300 ng/mL) and M6G in fat (46-4,600 ng/mL). Within-run and between-run accuracy (88.1-114.1%) and precision (CV 0.6-12.7%), matrix effects (CV 0.3-13.5%) and recovery (57.8-94.1%) were validated at two concentration levels; 3 and 150 ng/mL for codeine, norcodeine and morphine, and 46 and 2,300 ng/mL for C6G, M3G and M6G. Freeze-thaw and long-term stability (6 months at -80°C) was assessed, showing no significant changes in analyte concentrations (-12 to +8%). The method was applied in two authentic forensic autopsy cases implicating codeine in both therapeutic and presumably lethal concentration levels.

Metals and (metallo)proteins identification in vitreous humor focusing on post-mortem biochemistry

Evaluation of metals and (metallo)proteins in vitreous humor samples at different post-mortem intervals.