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Cholinergic Toxicity, Myasthenic Crisis and Cholinergic Crisis

by Pravin Shukle, MD

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      Slides Cholinomimentic Acivators and Effects ANS Pharmacology.pdf
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    00:01 So let's talk about other issues in cholinomimetic toxicity. Let's talk about nicotine.

    00:07 Think about what a person looks like or feels like when they first start smoking.

    00:12 First-time smokers who are exposed to new high levels of nicotine can become quite nauseous.

    00:18 Obviously you become acclimated to it and you don't feel that way later and you actually become addicted to nicotine.

    00:24 Exposure to Malathion and parathion, it really only is relevant at very high doses.

    00:29 Remember that these are prodrugs. So, they have to be metabolized to an active state.

    00:35 Now that happens much more in insects than it does in humans.

    00:38 So, when we talk about general use of Malathion and parathion that's safe for humans.

    00:46 But when you get exposed to very toxic levels where you're super concentrated, then you may have toxic levels accumulate in the human.

    00:55 Other aspects of cholinomimetic toxicity can be certain medicines like pyridostigmine, neostigmine, physostigmine. Here's an image of pyridostigmine.

    01:06 Now, let's look at the differences between myasthenic crisis and a cholinergic crisis.

    01:13 They're slightly different. The myasthenic crisis causes destruction of the acetylcholine receptor.

    01:20 So there is an increase in heart rate and an increase in blood pressure.

    01:26 Bowel and bladder incontinence.

    01:29 There's an absent cough reflex and an absent swallow reflex.

    01:33 Edrophonium gives temporary relief and the acetyl, that's because it's an acetylcholinesterase inhibitor.

    01:41 So there's more acetylcholine in the synaptic cleft that overcomes the lower numbers of the acetylcholine receptors that have been destroyed.

    01:51 That's why Edrophonium works in myasthenic crisis.

    01:55 Atropine doesn't help these symptoms. Now let's talk about a cholinergic crisis.

    02:02 A cholinergic crisis is when you have excess acetylcholine.

    02:06 An example is sarin gas. You have a decrease in blood pressure.

    02:10 You have abnormal cramps, nausea, vomiting and diarrhea.

    02:16 You have blurred vision you have pallor.

    02:19 You have some twitching in the face.

    02:22 Edrophonium does not help in this case but actually may precipitate either a cholinergic crisis and subacute patients or worsen the cholinergic crisis through an over dosage of the acetylcholine.

    02:38 And atropine here will improve symptoms.

    02:41 So you can see the difference between myasthenic crisis and cholinergic crisis.

    02:45 The difference is, and the important knowledge that edrophonium works in one and doesn't in another.

    02:51 And atropine will work in another and not in one.

    02:55 Okay. That's a tough topic, you did well.

    02:58 Go write your exam and show them what you know.


    About the Lecture

    The lecture Cholinergic Toxicity, Myasthenic Crisis and Cholinergic Crisis by Pravin Shukle, MD is from the course ANS - Pharmacology.


    Included Quiz Questions

    1. …Asphyxiation
    2. …Neurological damage
    3. …Heart block
    4. …Bradycardia and hypotension
    5. …Spinal shock
    1. Atropine
    2. Pralidoxime
    3. Leucovorin
    4. Flumazenil
    5. Benztropine
    1. Edrophonium
    2. Atropine
    3. Pralidoxime
    4. Phenylephrine
    5. Benztropine
    1. Urinary retention
    2. Abdominal cramps
    3. Facial muscle twitching
    4. Blurred vision
    5. Diarrhea

    Author of lecture Cholinergic Toxicity, Myasthenic Crisis and Cholinergic Crisis

     Pravin Shukle, MD

    Pravin Shukle, MD


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