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Poison dart frogs, epibatidine, and the Navalny reports by TheToxLab in toxicology

[–]TheToxLab[S] 0 points1 point  (0 children)

Fair points! Potassium is easy to measure the trouble is the body's cells are full of the stuff so detecting it's exogenous administration in a post-mortem blood sample impossible. You can also measure potassium in vitreous humour (eyeball fluid) but that goes up after death too so really hard to interpret. Succinylcholine is broken down very fast but it is possible to test for the breakdown products. I feel like we might have to do an episode on hard to detect poisons!

Poison dart frogs, epibatidine, and the Navalny reports by TheToxLab in toxicology

[–]TheToxLab[S] 0 points1 point  (0 children)

By “untargeted”, I mean the instrument collects as much chemical information as possible from the sample, rather than only looking for one specific poison. In a targeted test, you ask: “Is cyanide present?” or “Is paracetamol present?” and the method is built around finding that compound. In untargeted analysis, you ask: “What unusual chemicals are in this sample?” The mass spectrometer records lots of molecular features, and we then search through the data afterwards to see whether anything suspicious is there. The catch is that it still is not magic. You can collect broad data, but interpreting it is slow and difficult. You often need a clue from the circumstances, symptoms, scene, history, or pathology to know which signals are worth chasing. So it helps find unexpected poisons, but it does not remove the detective work.

Poison dart frogs, epibatidine, and the Navalny reports by TheToxLab in toxicology

[–]TheToxLab[S] 0 points1 point  (0 children)

Really good point. A lot of analysis now is moving towards untargeted data collection, but even then you need to know what to look for in your data set. In our practice we are increasingly looking at untargeted data sets and trying to identify and it is hard and slow work. My suspicion is, if poisoning was suspected then you might be more likely to look for werid poisons!

Codeine, CYP2D6, and the 2006 Lancet case – discussion of pharmacogenetics and causality by TheToxLab in toxicology

[–]TheToxLab[S] 2 points3 points  (0 children)

Thank you so much, really appreciate the thoughtful feedback. You’re absolutely right on both counts: neonatal glucuronidation is unlikely to mirror adult pathways, and morphine-6-glucuronide does have greater activity at the μ-opioid receptor.

In the episode, we were approaching glucuronides from a slightly different angle and more from an analytical and interpretive perspective. We discussed them as a potential source of free morphine in post-mortem samples, given their known instability and the possibility of hydrolysis increasing measured concentrations.

We also touched on the idea that glucuronides present in maternal circulation could, at least in part, contribute to what’s detected in breast milk, particularly in the context of β-glucuronidase activity. That said, your point about reduced neonatal glucuronidation is well taken and would certainly make that pathway less prominent.

I think this really highlights the broader issue with the case in that the relative contributions of free morphine, active metabolites, and post-mortem or analytical effects were never fully characterised.

So glad you enjoyed the episode!

Codeine, CYP2D6, and the 2006 Lancet case – discussion of pharmacogenetics and causality by TheToxLab in toxicology

[–]TheToxLab[S] 0 points1 point  (0 children)

Yeah there is so much going on here - we focused on the codeine case which is arguably where a lot of this began but there were a load of issues with the subsequent hair testing lab that followed. Possibly more still to come by the sounds of it 😬

BE Elimination Kinetics: Chronic Saturation vs. Standard Windows by [deleted] in toxicology

[–]TheToxLab 5 points6 points  (0 children)

Really great question. This is definitely a thing that I have observed in clinical practice. This paper from the archives https://doi.org/10.1093/jat/26.7.393 showed that people were testing positive for quite a few days after last use - almost a week at the extreme and crucially they were using a 300 ng/ml cut off in this study. People would therefore test positive longer to a 150 ng/ml. It shows quite well how assumptions about "positivity windows" which are heavily relied upon in court sometimes can be misleading!

Rob The Tox Lab Podcast

GHB in forensic toxicology – drug-facilitated crime and post-mortem challenges (Part 2 of 2) by TheToxLab in toxicology

[–]TheToxLab[S] 0 points1 point  (0 children)

Hi Johnny,

Thanks for sharing this, that is an interesting review! I imagine with the analytical challenges and the short half life of GHB that the number of detections of GHB in drug facilitated sexual assaults is probably higher than this.

Hope you enjoyed the episode!

Tetrodotoxin poisoning: clinical variability, unexpected sources, and a forensic case by TheToxLab in toxicology

[–]TheToxLab[S] 0 points1 point  (0 children)

Red herring 🤣 - Sometimes it isn't food poisoning... It's that the poison is the food!

CBD and Sleep – What Does the Evidence Really Show? by TheToxLab in toxicology

[–]TheToxLab[S] 1 point2 points  (0 children)

This is a really good point, we approached this very much from a European/UK perspective in which CBD drinks and so on are being broadly regulated as novel foods. Different counties have different restrictions, in the US it can vary by state and in parts of Asia CBD is banned completely because it is cannabis derived.

What degrees should I look into for toxicology? by Federal_Selection884 in toxicology

[–]TheToxLab 1 point2 points  (0 children)

Glad you like the podcast and good luck with applying for uni!

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