Ropinirole metabolite mimics a new psychoactive substance (4-HO-MET) in LC-MS/MS.

Liquid chromatography tandem mass spectrometry (LC-MS/MS) is often regarded as a highly reliable methodology for confirmatory testing in analytical toxicology, especially for detection of new psychoactive substances (NPS) by clinical and forensic laboratories. However, false positives still do occur and erroneous reporting can have substantial legal implications. In this study, we investigated into the mechanism behind a clinically implausible, but apparently analytically sound, finding of a NPS (4-hydroxy-N-methyl-N-ethyltryptamine; 4-HO-MET) in a urine specimen for toxicology screening by LC-MS/MS. We discovered that a ropinirole metabolite (N-despropyl-ropinirole) was the culprit of interference as it shares high structural similarities with 4-HO-MET. The chemical similarities eluded various rigorous regulatory guidelines for compound identification utilizing computer-aided spectral library matching. After careful scrutiny of the mass spectra and comparison with a reference specimen, the compound was correctly identified. Our findings emphasize the important synergy between scientists and pathologists in considering the clinical context, especially drug history, in clinical and forensic toxicology analysis on biological specimens. Mass spectra should be reviewed for relative ion ratios in case of doubt. Understanding drug metabolism is essential for troubleshooting and result interpretation.

Toxicity from illegitimate slimming agents - a 10-year case series at a tertiary toxicology laboratory in Hong Kong.

CONTEXT: This retrospective case-series study aims to provide an overview of the clinical, biochemical and analytical findings in patients who presented with toxicity related to the use of illegitimate slimming agents in Hong Kong from the perspective of a tertiary referral toxicology laboratory. METHODS: All clinical cases referred to the Hospital Authority Toxicology Reference Laboratory, Hong Kong with clinical suspicion of illegitimate slimming agent-related toxicity between January 2008 and December 2017 were reviewed retrospectively. The use of illegitimate slimming agents included the use of (1) deregistered slimming agents, (2) drug analogues that were not registered drugs, (3) registered drugs not approved for the indication of weight reduction (whether prescribed by a doctor or not), and (4) prescription-only slimming agents without a doctor's prescription. Patients taking registered weight-reducing drugs prescribed by a doctor were excluded. Patient demographics, clinical features, relevant laboratory investigations, and toxicological findings were analyzed. RESULTS: From 2008 to 2017, a total of 346 patients were analytically confirmed by our laboratory to have clinical toxicity related to the use of illegitimate slimming agents. The median age of the patients was 27 years and 92.5% of the patients were female. The most common clinical presentations included psychiatric features, sympathomimetic toxicity, hypokalemia, and abnormal thyroid function tests. Fatal or severe clinical toxicity was observed in 10% of the cases. The major classes of drugs detected on our analytical platforms were stimulants (e.g., sibutramine), laxatives (e.g., anthraquinones), diuretics (e.g., hydrochlorothiazide), and thyroid hormones (e.g., animal thyroid tissue). These illegitimate slimming agents were obtained from various sources including the Internet, over-the-counter in community pharmacy, or unspecified local sources. DISCUSSION AND CONCLUSIONS: The use of slimming agents is common worldwide; apart from taking registered slimming agents prescribed by registered practitioners, many users obtain slimming agents from various illegitimate sources. The unregulated use of these drugs can be associated with significant clinical toxicity. This study provides a current landscape of illegitimate slimming agent toxicity in Hong Kong to frontline clinicians and other toxicology professionals. Collaboration between clinicians, laboratories, and government authorities would be imperative to prevent further health adversities related to the misuse of these agents.

Adulteration of proprietary Chinese medicines and health products with undeclared drugs: experience of a tertiary toxicology laboratory in Hong Kong.

AIMS: Proprietary Chinese medicines (pCMs) and health products, generally believed to be natural and safe, are gaining popularity worldwide. However, the safety of pCMs and health products has been severely compromised by the practice of adulteration. The current study aimed to examine the problem of adulteration of pCMs and health products in Hong Kong. METHODS: The present study was conducted in a tertiary referral clinical toxicology laboratory in Hong Kong. All cases involving the use of pCMs or health products, which were subsequently confirmed to contain undeclared adulterants, from 2005 to 2015 were reviewed retrospectively. RESULTS: A total of 404 cases involving the use of 487 adulterated pCMs or health products with a total of 1234 adulterants were identified. The adulterants consisted of approved drugs, banned drugs, drug analogues and animal thyroid tissue. The six most common categories of adulterants detected were nonsteroidal anti-inflammatory drugs (17.7%), anorectics (15.3%), corticosteroids (13.8%), diuretics and laxatives (11.4%), oral antidiabetic agents (10.0%) and erectile dysfunction drugs (6.0%). Sibutramine was the most common adulterant (n = 155). The reported sources of these illicit products included over-the-counter drug stores, the internet and Chinese medicine practitioners. A significant proportion of patients (65.1%) had adverse effects attributable to these illicit products, including 14 severe and two fatal cases. Psychosis, iatrogenic Cushing syndrome and hypoglycaemia were the three most frequently encountered adverse effects. CONCLUSIONS: Adulteration of pCMs and health products with undeclared drugs poses severe health hazards. Public education and effective regulatory measures are essential to address the problem.

Supraventricular tachycardia and acute confusion following ingestion of e-cigarette fluid containing AB-FUBINACA and ADB-FUBINACA: a case report with quantitative analysis of serum drug concentrations.

BACKGROUND: AB-FUBINACA and ADB-FUBINACA are structurally similar synthetic cannabinoids with potent CB1 receptor agonistic effects. Very little is known about their pharmacology and toxicology. OBJECTIVE: To report a case of supraventricular tachycardia and acute confusion after ingestion of e-cigarette fluid containing AB-FUBINACA and ADB-FUBINACA, with quantitative analysis of the serum drug concentrations. CASE REPORT: A healthy 24-year-old man ingested two drops of e-cigarette fluid which were later found to contain AB-FUBINACA and ADB-FUBINACA. Within 30 min of ingestion, he became somnolent, confused, and agitated, with palpitation and vomiting. On arrival to the emergency department, a short run of supraventricular tachycardia was noted, which resolved spontaneously. Bedside urine immunoassay failed to detect recreational drugs. Laboratory blood tests showed mild hypokalemia. Exposure to AB-FUBINACA and ADB-FUBINACA was confirmed analytically, with serum concentrations of 5.6 ng/mL and 15.6 ng/mL, respectively, in the blood sample collected on presentation. The patient recovered uneventfully with supportive treatment and was discharged 22 h after admission. DISCUSSION: AB-FUBINACA and ADB-FUBINACA are orally bioavailable with rapid onset of toxicity after ingestion. In this case, supraventricular tachycardia was likely the result of exposure to AB-FUBINACA and ADB-FUBINACA. The serum concentrations of AB-FUBINACA and ADB-FUBINACA were higher than those previously reported in fatal cases. CONCLUSION: In the context of acute poisoning, the presence of unexplained tachyarrhythmias, confusion, and a negative recreational drug screen should prompt clinicians to consider synthetic cannabinoid toxicity as a differential diagnosis.

Hepatic nitroreduction, toxicity and toxicokinetics of the anti-tumour prodrug CB 1954 in mouse and rat.

5-(Aziridin-1-yl)-2,4-dinitrobenzamide (CB 1954), a promising anti-tumour compound, is associated with clinical hepatotoxicity. We have previously demonstrated that human liver preparations are capable of endogenous 2- and 4-nitroreduction of CB 1954 to generate highly potent cytotoxins. The present study initially examined the in vitro metabolism of CB 1954 in S9 preparations of several non-clinical species and strains. The CD-1 nu/nu mouse and Sprague-Dawley rat were subsequently chosen for further assessment of in vivo metabolism and hepatotoxicity of CB 1954, as well as the mechanisms that may be involved. Animals were administered the maximum tolerated dose (MTD). At 562 micromol/kg, the mouse exhibited transaminase elevation and centrilobular hepatocyte injury. Moreover, thiol adducts as well as hepatic glutathione depletion paralleled temporally by maximal nitroreduction were observed. The rat had a much lower MTD of 40 micromol/kg and showed signs of gastro-intestinal disturbances. In contrast to mouse, peri-portal damage and biliary changes were observed in rat without any alterations in plasma biomarkers or hepatic glutathione levels. Immunohistochemical analysis did not reveal any correlation between the location of injury and expression of cytochrome P450 reductase and NAD(P)H quinone oxidoreductase 1, two enzymes implicated in the bioactivation of this drug. In conclusion, the present study showed that following administration of CB 1954 at the respective MTDs, hepatotoxicity was observed in both mouse and rat. However, the degree of sensitivity to the drug and the mechanisms of toxicity involved appear to be widely different between CD-1 nu/nu mice and Sprague-Dawley rats.

Aerobic 2- and 4-nitroreduction of CB 1954 by human liver.

5-(Aziridin-1-yl)-2,4-dinitrobenzamide (CB 1954) is an anti-tumour prodrug which recently entered clinical trials in combination with Escherichia coli nitroreductase in a gene-directed enzyme prodrug therapy (GDEPT) context. A Phase I trial of the prodrug, however, revealed dose-limiting hepatotoxicity (transaminitis). The aim of this study was to find out whether the prodrug undergoes reductive metabolism in human liver to cytotoxic metabolites which may contribute to this clinical toxicity. CB 1954 (2.5-250 microM) was incubated with human liver preparations (2-8 mg/mL of S9, cytosolic or microsomal proteins) in the presence of NAD(P)H (1 mM). The NADH- and NADPH-dependent formation of both 2- and 4-nitroreduction products was demonstrated, with NADPH being the preferred cofactor, by HPLC and mass spectrometry. The major metabolite formed in all three human liver preparations was the 4-hydroxylamine, a potent DNA cross-linking cytotoxin. The 2-hydroxylamine and 2-amine metabolites were also detected, both of which have also been demonstrated to be highly cytotoxic. 2-Nitroreduction was far greater in S9 compared with cytosol and was not detected in microsomal preparations. Although 2- and 4-nitroreduction of CB 1954 was inhibited under hyperoxic conditions, substantial metabolism was observed under atmospheric oxygen levels. These studies demonstrate that human liver is capable of aerobic reductive bioactivation of CB 1954 to cytotoxic metabolites in vitro, possibly involving multiple enzymes, which may account for the clinical hepatotoxicity observed.