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TRJF t1_j6dqoel wrote

In a criminal justice context, an expert toxicologist's opinion is often in the form of whether the concentration in the blood is "consistent with a therapeutic range."

So, for a given medication, there will be studies that say something like (just some random numbers here) "this medication is usually dispensed in doses of 10mg once per day at the low end and 70mg once per day at the high end. People who take a 10mg dose typically have a blood concentration that peaks between X and 2X after approximately an hour, and people who take a 70mg dose typically have a blood concentration that peaks between 7X and 14X after an hour. The substance in the blood has a typical half-life of 8 to 12 hours. On a daily dose, baseline blood levels will stabilize at Y for 10mg daily and Z for 70mg daily."

So, let's say someone has 80X in their blood. A toxicologist will be able to say with confidence "that's not consistent with a therapeutic dose - this person ingested way more of the substance than a doctor would ever prescribe." So, either drug abuse or poisoning.

Now, say someone has 2X in their blood. A toxicologist can say "that's consistent with a therapeutic dose" - but not much more than that. It's quite possible that person took 10mg or 20mg an hour ago, and takes that every day - but they may have taken 70mg 16 to 24 hours ago as a one-off. Or they may have taken 40mg 12 hours ago, and every other day for the last month. Or they may have taken 1,000mg 48 hours ago.

So, that's some of the nuance: it's fairly easy to rule out certain dosage quantities/timelines, but it's much harder to say what actually did happen. A lot of the time, the first one's all that's needed.

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bynarie OP t1_j6dtny4 wrote

Very good explanation. Thank you.

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[deleted] t1_j6eg5ia wrote

[removed]

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teratogenic17 t1_j6ejw4s wrote

I'd like to see some doctors turn from a punitive and sometimes deadly approach with Vicodin.

I have chronic nerve damage pain, and I had to pressure my otherwise sympathetic doctor, to remove the acetaminophen from my daily dosage.

If they had not done that, I would surely have died by now of liver and kidney failure, over the past decade.

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chocokittynyaa t1_j6ejjnm wrote

Kidney/liver issues definitely, but also genetics can affect drug distribution and elimination for many medications (for example, loss or gain of function mutations in drug transporters).

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momoneymocats1 t1_j6ffrnc wrote

In other words, they explain a drugs pharmacokinetics and pharmacodynamics

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zvii t1_j6fmcej wrote

Much needed addition, thank you!

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GoldenMegaStaff t1_j6ehzcv wrote

Is there typically difficulty in getting the specific prescription information from this suspect/victim instead of having to work with all these assumptions?

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ic3man211 t1_j6ey0ua wrote

Op is describing a case where someone has committed a crime and the police are determining if the amount of drug in their system at the time is abnormally high and would have caused some issues…not like the offender would volunteer they took too much of their painkiller and drove into oncoming traffic

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rudbek-of-rudbek t1_j6expou wrote

So to get any sort of reliable number you would definitely need to know when the drug was ingested. Is this correct?

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curiousnboredd t1_j6eiywk wrote

is this an example of high sensitivity and low specificity? Since you can determine a positive for sure (the 80X example) but can’t determine if the negative is truly a negative or false negative (the latter example)

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