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TheSaxonPlan t1_j1eh1v8 wrote

Reply to comment by Littlebotweak in An animal tranquilizer is showing up in the nation's illicit drug supply by jivatman

We use a ketamine/xylazine mix for long-acting anesthesia during mouse brain surgeries in the brain cancer research lab I work in.

>"Ketamine ia a noncompetitive, centrally acting, dissociative general anesthetic that provides amnesia, analgesia, and immobility. Ketamine typically is used as an adjunct anesthetic, due to its limited ability to provide adequate skeletal muscle relaxation. When combined with xylazine, the combination is regarded as the agent of choice for rodent injectable anesthesia. The popularity of ketamine–xylazine (KX) is mainly due to its supplemental effects (that is, analgesic properties, muscle relaxation, and sedation)."

>"Xylazine (Rompun, Bayer) produces moderate sedation and minimal analgesia in rabbits. It is seldom used as a sole agent but is given in combination with ketamine. The combination causes cardiovascular and respiratory depression, and cardiac arrhythmias are produced at high doses. Xylazine and ketamine have been associated with a high mortality rate (Flecknell et al., 1983)."

Ketamine info source

Xylazine info source

I can attest to the lethality of ketamine/xylazine. We try to titer our doses to be the minimum necessary to keep mice asleep and immobile, but not all mice respond the same, and they develop resistance to ketamine the longer it is used. We sometimes have to "bump" their doses and even small amounts can lead to respiratory and/cardiac failure. Our senior tech has successfully resuscitated several mice by doing mini chest compressions and restored breathing. I've saved two this way. But we still lose between 1-5% of mice due to overdose in our experiments.

I am a doctor, but the Ph.D. kind, not the M.D. kind lol

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tehmlem t1_j1eie6x wrote

I think technically at this point you're a veterinarian

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Littlebotweak t1_j1elf9s wrote

Thanks, doc!

Yea, ketamine has a super quick tolerance build (recreational experience). I guess the dose schedule for testing is such that you can't give them a day or two in between? That might could help, but I get it if it doesn't fit with the experiment design for [reasons].

Is the xylanine for immobility? I imagine ketamine isn't an overall iwin button for sedation, considering the k-holes I've seen some poor saps go down where they're still standing and even dancing. But, hey, their respiratory rates are fine, after all. XD

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TheSaxonPlan t1_j1epi76 wrote

I've never had to dose two days in a row as our surgeries are 4-5 days apart and we use short-acting (and very stinky) isoflurane gas for quick post-op procedures like fixing their sutures/staples or administering fluids. But even with that length of time, we often have to increase the dose by 10-20% to achieve sufficiently deep anesthesia.

Yeah, the xylazine is for muscle relaxation and a little bit for the pain-killing effect. Since we are literally drilling through the skull and putting a needle into their brain, we don't want any twitches or wiggles! Don't know much about ketamine in people, though I am intrigued by its use as an anti-depressant!

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TelluricThread0 t1_j1f50gp wrote

Ketamine is showing a lot of promise for treating depression. The effects are relatively short term though. Patients need another infusion every couple months or so.

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gruntsifyouwill t1_j1fsir4 wrote

Considering that the vast majority of medications for depression are taken daily, I'd say ketamine actually has remarkably long lasting effectiveness.

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TelluricThread0 t1_j1fwx9j wrote

It's not when you have better longer lasting options like psilocybin therapy that can see patient symptoms go into remission for a year or even longer. It can treat root causes of mental illnesses leading to better outcomes and you don't have patients being dependent on many ketamine infusions per year. Don't get me wrong it's great they're finally trying different things besides antidepressants but I see psilocybin as much more efficacious comparatively.

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---------_----_---_ t1_j1intx9 wrote

The other issue with ketamine is that it's pretty hard on the kidneys when used frequently. If you're passing blood in your urine, that's not a good sign. Stop the K immediately and don't do more later.

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Drink-my-koolaid t1_j1f1s2n wrote

How does one resuscitate a little mouse? Do you have to use one finger and do compressions very quickly?

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badestzazael t1_j1hhuc8 wrote

Mice are more resistant than humans to the effects of ketamine i.e mice need more mg's per kilogram than humans.

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