Welcome to our ongoing coverage of the Minnesota murder trial of Derek Chauvin, over the in-custody death of George Floyd. I am Attorney Andrew Branca for Law of Self Defense, providing guest commentary and analysis of this trial for Legal Insurrection.
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I wanted to share with all of you some additional information that has been shared with me on the issue of opioid tolerance. I caution again that I remain thoroughly non-expert on the subject, but I do now have some actual research papers that I can share with you, and perhaps we can all develop a better-founded understanding of tolerance in the context of this case.
Opioid tolerance is of relevance in this case because it ties into the issue of cause of death of George Floyd. Specifically, was it Chauvin’s knee that killed Floyd, or was it Floyd’s three-fold fatal dose of fentanyl, in combination with methamphetamine, that killed him. (Also relevant, of course, is Floyd’s existing severe hypertensive and cardiovascular disease, as well as the physiological context of Floyd choosing to forcibly resist efforts by multiple officers to make his lawful arrest, but those factors are outside the scope of this content.)
During opening arguments Prosecutor Blackwell suggested to the jury that although Floyd’s levels of fentanyl might have been a fatal dose to a typical person, they would not have been a fatal dose to Floyd. Why? Because Floyd was not a typical person, he was an opioid addict, and opioid addicts develop tolerance to their drugs. Thus, according to this line of argument, Floyd would have been substantially less vulnerable to death by fentanyl overdose than would the non-addict.
This line of argument struck me as inconsistent with my own understanding—admittedly a layman’s understanding—of how tolerance works in this context.
In. yesterday’s wrap-up post I wrote:
I don’t believe tolerance works to make an addict more resilient against death by overdose, but merely makes it harder to get the desired high. The mechanism of death by overdose and the mechanism of the high are fundamentally different. The brain develops tolerance to the drug and so requires a greater concentration of drug to get the same high. But that has nothing to do with how the drug kills. In the case of fentanyl, death is usually the result of the drug achieving a level sufficient to stop respiration—and I don’t believe the body develops any tolerance to that biological mechanism.
In other words, if an addict first needs 2 units of drug to get high, he’ll eventually need 4, then 8, then 10, etc. But if a fatal dose is 20 units, then whenever the addict hits 20, he dies, and it matters not a whit how much tolerance he’s developed in the context of getting high. Indeed, one of the great dangers to addicts is that they grow ever closer to fatal overdose as their increasing tolerance to achieve a high demands doses that approach ever closer to fatal levels.
Again, however, that’s a layman’s understanding of these issues. I look forward to hearing expert testimony during the trial.
Now, it appears now that there is a fundamental error in that statement–in fact tolerance develops with respect to both the “high” and with respect to respiratory depression. The fundamental point remains, however, because the rate at which tolerance develops for each is different. Specifically, it appears that tolerance to the “high” grows much more rapidly than does tolerance to respiratory depression.
This morning I found that a helpful comment (thanks Dan, over at the Law of Self Defense blog!) that kindly provided links to two scientific papers on this subject, and I’d like to share those with all of you. I caution again, I’m just a small-town lawyer, not a doctor, and two papers do not make a claim authoritative, but they do constitute more scientific support than I’d cited previously, so I thought them worth sharing. (Both papers are freely accessible without cost, and I’ve linked them below.)
I also caution that the scientific papers are written in the same style and tone as scientific papers are typically written, which can make them rather cumbersome and somewhat opaque to the non-expert reader, but that’s the way these things go.
Both papers make the argument, supported by their findings, that while tolerance may develop both in terms of the “high” (or, in a therapeutic setting, the pain relief or analgesic effect sought) and in terms of fatal overdose (in the case of opioids, usually fatal respiratory depression, referred to as opioid-induced respiratory depression, or OIRD), that these tolerances do not develop at the same rate.
Instead, tolerance of the “high” grows much faster than does tolerance for overdose. The result is that the “window” of safe dosing by opioid addicts, in which the desired high is achieved without fatal overdose, grows smaller and smaller over time, meaning the danger of overdose grows increasingly likely over time.
The first paper, published in the scientific journal Anesthesiology, is titled “Differential Opioid Tolerance and Opioid-induced Hyperalgesia: A Clinical Reality”, and it reads in relevant part:
In the early postoperative setting, differential tolerance development to analgesia and respiratory depression is most relevant. Patients receiving chronic opioids for pain control, especially at high doses, should be assumed to have developed less tolerance to opioid-induced respiratory depression than to analgesia. This means that equianalgesic doses of opioids administered perioperatively will induce more respiratory depression in opioid-tolerant than in opioid-naive patients (note that the dose required to reach this equianalgesic effect will likely be much greater in the opioid-tolerant patient). In other words, contrary to what intuitively would seem to be the case, the opioid-tolerant patient is at an increased risk for respiratory depression when his or her postoperative pain is treated adequately with opioids.
The second paper, published in the scientific journal Clinical Pharmacology and Therapeutics, is titled “Tolerance to Opioid‐Induced Respiratory Depression in Chronic High‐Dose Opioid Users: A Model‐Based Comparison With Opioid‐Naïve Individuals,” and it reads in relevant part:
Prolonged use of opioids, such as morphine, oxycodone, or fentanyl, is associated with addiction, physical dependence, and tolerance.Tolerance occurs due to adaptive changes at the neuronal level and results in the need for dose escalation to maintain the desired intensity of response.Importantly, the consumption of high‐dose or potent opioids is potentially life‐threatening, as it may cause opioid‐induced respiratory depression (OIRD) and ultimately death from silencing of neurons in brainstem respiratory networks.When tolerance to analgesic and euphoric opioid effects coincides with tolerance to opioid respiratory effects, tolerance may reduce the respiratory effects of opioids. However, several animal studies indicate that tolerance to the analgesic and respiratory effects are dissociated with lower and slower development of tolerance to OIRD than of other opioid effects.
Assuming that tolerance to the “high” of opiates develops substantially more rapidly than does tolerance to OIRD, and that the window of safe dosing thus grows ever smaller and the risk to the addict of fatal overdose ever greater, this would run counter to the state’s apparent argument that Floyd’s admitted opioid addiction actually made him less likely to experience a fatal opioid overdose than would be the case for a non-addict.
OK, folks, that’s all I have for now.
Join us later this morning for our LIVE coverage of the court proceedings in Minnesota v. Chauvin, and for our end-of-day wrap-up commentary and analysis, both right here at Legal Insurrection.
Until next time, stay safe!
Attorney Andrew F. Branca
Law of Self Defense LLC
Attorney Andrew F. Branca’s legal practice has specialized exclusively in use-of-force law for thirty years. Andrew provides use-of-force legal consultancy services to attorneys across the country, as well as near-daily use-of-force law insight, expertise, and education to lawyers and non-lawyers alike in the form of blog posts, video, and podcasts, through the Law of Self Defense Membership service. If this kind of content is of interest to you, try out our two-week Membership trial for a mere 99 cents, with a 200% no-question- asked money-back guarantee, here: Law of Self Defense Membership Trial.
[Featured image is a screen capture from video of George Floyd’s arrest on May 25, 2020.]
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