Ultraviolet-Visible and High-Resolution Mass Spectrometry for the Identification of Cyclopropyl-Fentanyl in the First Fatal Case in Spain.

Here we report the identification and quantitation of cyclopropyl-fentanyl in a fatality casework occurred due to a poly-drug toxicity in Spain in December 2017. The cyclopropyl-fentanyl was identified in non-biological (paraphernalia) and biological samples (whole-blood, vitreous humor and urine). Conventional techniques (GC-MS) and the UV-Vis spectral allowed differencing between the two structural isomer compounds of fentanyl (cyclopropyl and crotonyl) when the CRM was not available at the laboratory. Both of the drugs have the same MS spectra but different UV-Vis spectra due to the presence of an additional chromophore group in the case of crotonyl. The cyclopropyl-fentanyl detection allowed generating an alert and contributing to the surveillance and detection of this dangerous substance found mixed in doses of clandestine sale heroin. Then, high-resolution analytical techniques (LC-HRMS-MS), showed limitations for the identification of the isobaric fentanyl compounds but they had a high potential for fentanyl metabolites identification. Two tentative metabolites were identified in urine samples: cyclopropyl-norfentanyl and N-methyl cyclopropyl-norfentanyl. Finally, the systematic routine method (LC-MS-MS) was validated and applied to the quantification of cyclopropyl-fentanyl in a blood sample. A obtained value (20.4 ng/mL) was in the range of those reported in other cases in different countries (from 8 to 30 mg/ mL), being the determined concentration of cyclopropyl-fentanyl high enough to infer that this fentanyl analog had a main role as cause of death. As far as we know, this is the first fatality reported in Spain involving cyclopropyl-fentanyl.

Stimulatory effect of xenin-8 on insulin and glucagon secretion in the perfused rat pancreas.

Xenin is a 25-amino acid peptide of the neurotensin/xenopsin family identified in gastric mucosa as well as in a number of tissues, including the pancreas of various mammals. In healthy subjects, plasma xenin immunoreactivity increases after meals. Infusion of the synthetic peptide in dogs evokes a rise in plasma insulin and glucagon levels and stimulates exocrine pancreatic secretion. The latter effect has also been demonstrated for xenin-8, the C-terminal octapeptide of xenin. We have investigated the effect of xenin-8 on insulin, glucagon and somatostatin secretion in the perfused rat pancreas. Xenin-8 stimulated basal insulin secretion and potentiated the insulin response to glucose in a dose-dependent manner (EC(50)=0.16 nM; R(2)=0.9955). Arginine-induced insulin release was also augmented by xenin-8 (by 40%; p<0.05). Xenin-8 potentiated the glucagon responses to both arginine (by 60%; p<0.05) and carbachol (by 50%; p<0.05) and counteracted the inhibition of glucagon release induced by increasing the glucose concentration. No effect of xenin-8 on somatostatin output was observed. Our observations indicate that the reported increases in plasma insulin and glucagon levels induced by xenin represent a direct influence of this peptide on the pancreatic B and A cells.

Interrelationship among insulin, glucagon and somatostatin secretory responses to exendin-4 in the perfused rat pancreas.

We have investigated the effect of exendin-4 on insulin, glucagon and somatostatin output in the perfused rat pancreas. At 9 mM glucose, exendin-4 potentiated the insulin and somatostatin responses to arginine and reduced the glucagon response to this amino acid. Thus, this reduction might be thought to be paracrine-mediated through the concomitant increase in insulin and somatostatin concentrations. At 3.2 mM glucose, exendin-4 did not affect insulin secretion, reduced glucagon release and stimulated somatostatin output. Furthermore, exendin-4 reduced glucagon secretion as induced by a glucose decline (from 11 to 3.2 mM) without affecting insulin or somatostatin responses. In summary, exendin-4 stimulated insulin and somatostatin secretion and reduced glucagon release. The glucagonostatic effect of exendin-4 was observed under conditions in which insulin and somatostatin were not affected, thus indicating that exendin-4, per se, inhibits A-cell secretion. Indeed, an additional glucagonostatic effect of exendin-4, mediated by its stimulation of insulin and/or somatostatin secretion, cannot be ruled out.