Metformin - Postmortem fatal and non-fatal reference concentrations in femoral blood and risk factors associated with fatal intoxications

Bariatric surgery and changes in metformin distribution: About a fatal case

A 65 year-old woman, suffering from mellitus type 2 diabetes and obesity, died at home, three days after bariatric surgery (Roux-en-Y gastric by-pass: RYGB). Her treatment, including metformin and dapagliflozin, was stopped before surgery and not postoperatively reinstalled. A forensic autopsy, toxicological and histological analyses were performed. No macroscopic or microscopic evidence of digestive perforation or peritonitis was identified, excluding an early surgery complication as the cause of death. Toxicological analysis revealed the presence of Metformin in all matrices tested, with a potentially fatal blood concentration. Death was attributed to lactic acidosis caused by a metformin overdose. With no evidence for suicide by ingestion of metformin, the authors supposed that the bariatric surgery might have caused changes in the absorption of metformin, leading to a rapid overdose and death. The only study in the literature on this subject, demonstrated a significant increase in the bioavailability of metformin following oral administration in gastric bypass patients. Thus, it can be anticipated that a therapeutic dose can become toxic when administrated to a subject who recently modified her digestive equipment. As this represents the first case of metformin overdose following bariatric surgery, further cases will be needed to confirm our initial observations.

Validation of a non-targeted method devoted to identification and quantitation of toxicologically relevant compounds in plasma with HRMS

The objective of this study was to develop and validate a simple method using liquid chromatography hyphenated to high resolution mass spectrometry (HRMS) allowing both the performance of a non-targeted screening and the simultaneous quantification of 29 compounds of interest in clinical and forensic toxicology. Extraction was done with QuEChERS salts and acetonitrile, after addition of internal standard to 200 μL of human plasma samples. The mass spectrometer was an Orbitrap, with a heated electrospray ionization (HESI) probe. The analyses were carried out in full scan experiment with a nominal resolving power of 60,000 FWHM within the 125-650 m/z mass range, followed by four cycles of data dependent analysis (DDA) with a mass resolution of 16,000 FWHM. The untargeted screening was evaluated using 132 compounds, mean limit of identification (LOI) was 8.8 ng/mL (min = 0.05 ng/mL, max = 500 ng/mL) and mean limit of detection (LOD) was 0.25 ng/mL (min = 0.05 ng/mL, max = 5 ng/mL). The method was linear in the 5 to 500 ng/mL range (0.5 to 50 ng/mL for cannabinoids, 6-acetylmorphine and buprenorphine) with correlation coefficients > 0.99, intra- and inter-day accuracy and precision were < 15% for all compounds. The method was successfully applied to 31 routine samples.

Deliberate Self-Poisoning: Real-Time Characterization of Suicidal Habits and Toxidromes in the Food and Drug Administration Adverse Event Reporting System

INTRODUCTION

Deliberate self-poisoning (DSP) using drugs is the preferred method of suicide at a global level. Its investigation is hampered by limited sample sizes and data reliability. We investigate the role of the US FDA Adverse Event Reporting System (FAERS), a consolidated pharmacovigilance database, in outlining DSP habits and toxidromes.

METHODS

We retrieved cases of 'intentional overdose' and 'poisoning deliberate' from the FAERS (January 2004-December 2021). Using descriptive and disproportionality analyses, we estimated temporal trends, potential risk factors, toxidromes, case-fatality rates and lethal doses (LDs) for the most frequently reported drugs.

RESULTS

We retrieved 42,103 DSP cases (17% fatal). Most cases were submitted in winter. Reports of DSP involved younger people, psychiatric conditions, and alcohol use, compared with non-DSP, and fatality was higher in men and older patients. Suspected drugs were mainly antidepressants, analgesics, and antipsychotics. Multiple drug intake was recorded in more than 50% of the reports, especially analgesics, psychotropics, and cardiovascular agents. The most frequently reported drugs were paracetamol, promethazine, amlodipine, quetiapine, and metformin. We estimated LD25 for paracetamol (150 g).

CONCLUSION

Worldwide coverage of the FAERS complements existing knowledge about DSP and may drive tailored prevention measures to timely address the DSP phenomenon and prevent intentional suicides.

Specific interpretation of hair concentrations in 2 fatal metformin intoxication cases

Hair analysis is very useful for toxicological investigations since, by providing a wider detection window, it gives the possibility to perform a retrospective study on the historical consumption of a substance. Unfortunately, there are no data available for hair concentrations in metformin-related deaths. In this study, the authors present 2 cases of fatal metformin intoxication in which, for the first time, hair analysis was performed using a specific GC-MS/MS method. Metformin was tested positive in femoral blood (112.3 mg/L and 64.7 mg/L respectively) and cardiac blood (226.9 and 203.2 mg/L) of the two subjects. For case 1, other samples were also tested positive, including vitreous humor (31.1 mg/L) and gastric contents (773.5 mg/L). In case 2, metformin was measured at 844.9 mg/L in urine. Metformin hair concentrations were 28.3-44.8 and 22.5 ng/mg for both cases, respectively. The concentrations found in the 2 fatal cases are clearly higher than those obtained in a previous study with subjects under treatment (0.3-3.8 ng/mg) or those found in 3 post-mortem cases where metformin death was excluded (0.6-1.4 ng/mg). Excessive sweating during the agonal phase due to fatal hypoglycemia could explain these elevated concentrations as sweat can have contaminated the hair.

Development of a new GC-MS/MS method for the determination of metformin in human hair

Diabetes mellitus is one of the most important public health challenges. Metformin (1,1-dimethylbiguanide) represents the "gold standard" for the treatment of diabetes mellitus type 2. Despite its important role in reducing mortality and morbidity in the diabetic population, metformin is associated with an increased risk of stroke. To document exposure to a drug, hair is considered to be the specimen of choice to complement blood and urine, since it provides historical detail of a subject's chronic exposure to drug(s). Measuring hair concentration of metformin can be important for forensic toxicologists investigating criminal poisoning or Munchausen's syndrome by proxy. In clinical toxicology, drug monitoring using hair to document metformin observance has not yet been described. To document the interest of hair analysis for metformin, the authors have developed and validated a method using a gas-chromatography tandem mass spectrometry system and applied it to authentic hair obtained from 9 diabetic patients under daily treatment. The validation procedure demonstrated a LOD an LOQ of 1 and 100 pg/mg, respectively and acceptable linearity, repeatability and reproducibility. The hair of the 9 patients tested positive in the low ng/mg range with concentrations ranging from 0.3 to 3.8 ng/mg. It seems obvious, in comparison with other drugs, that metformin is badly incorporated into hair, as the daily dosage varied from 1 to 3 g. Although limited in the number of subjects, the study allowed to postulate a possible correlation between daily dose and concentration in dark hair, while for light hair no correlation was found.