USMLE Step 2 Review 19 12 Drugs of Choice Antipsychotics 3

USMLE Step 2 Review 19 12 Drugs of Choice Antipsychotics 3


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Begin 19 12 Drugs of Choice Antipsychotics 3 Transcription

What are 4 low-potency antipsychotics with higher potential for anticholinergic, antihistaminergic, and antiadrenergic side effects? Give them in alphabetical order.

  • Chlorpromazine, Clozapine, Thioradazine, Risperidone.

Important- which of these is not used very much anymore because it has so many side effects?

  • Chlorpromazine.

Trade name for Chlorpromazine?

  • Thorazine.

Which of these has much lower risk for the side effects of Chlorpromazine and yet has rare, fatal side effect?

  • Clozapine.

Trade name for Clozapine?

  • Clozaril.

How often is this side effect of Clozapine/Clozaril fatal with patients?

  • About 1% of the time.

And what is the side effect?

  • Agranulocytosis.

What must the physician monitor weekly, then, for the patient on Clozapine/Clozaril?

  • The white blood cell count.

Which one of these is used at the same dosage levels as Chlorpromazine, but has far less risk of immediate side effects too adverse for the patient to tolerate, and whose side effect profile is strongest in the area of being anticholinergic?

  • This is Thioradizine.

Trade name?

  • Melaril.

And finally, which one of these has by far the lowest dosage levels required and yet, has the side effect profile of a low-potency antipsychotic, except that it does cause minimal sedation (the antihistaminergic)?

  • This is Risperidone.

And the trade name for Risperidone?

  • Risperidol.

Before we move on to the different side effect profile of the high potency antipsychotics, There is another toxicity syndrome that shares a lot of similarities with the anticholinergic toxicity syndrome we just covered.

What is it?

  • Sympathomimetic toxicity- adrenergic overstimulation.

What are the 2 drugs or classes of drugs that most commonly cause sympathomimetic toxicity?

  • Cocaine and the amphetamines.

Now, when a patient first comes into the emergency room with sympathomimetic toxicity, they will hourly display some of the signs of anticholinergic toxicity.

Remembering our memory key for anticholinergic, anti-cool, and the 5 signs (hot and dry, red, blind, crazy), which 4 of these will be the same with the sympathomimetic toxic patient?

  • Hot, red, blind, crazy.

So, when you just look at the patient, it may not be immediately evident whether the patient is suffering from anticholinergic or sympathomimetic toxicity.

Now, with sympathomimetic intoxication that is mild, or subtoxic, the patient may not have all 4 of these signs (hot, red, blind, crazy).

Which 2 are most likely to be different with much milder sympathomimetic intoxication?

  • The patient may be cool and pale, instead of hot and red.

So how do you tell these patients apart?

  • There are 2 key differences that should make it easier to distinguish between anticholinergic and sympathomimetic.

What will these 2 findings be for the sympathomimetic patient?

  • First, eyes and skin will probably be wet. Second, bowel sounds should be hyperactive.

Now, what outward sign of bowel hyperactivity due to sympathomimetic overstimulation might you see?

  • Diarrhea.

Ok, now what about the dry mouth and nose, and urinary retention, are other hallmarks of anticholinergic?

  • Mouth and nose may be dry or wet, not reliable. Urinary retention will be present and similar to the anticholinergics.

All right, let’s summarize. Please list the 5 findings in sympathomimetic toxicity that will probably be the same as for anticholinergic toxicity, and note that the heading “dry” will contain only 1 feature that’s the same instead of the 6 features of dry with anticholinergics. Ok, here we go.

Find the same for both sympathomimetic and anticholinergics?

  • Hot, urinary retention for dry, red, blind, crazy.

Which 2 signs under the “dry” heading are variable?

  • Mouth and nose.

And which 3 of “dry” are opposite for sympathomimetic?

  • Wet eyes, wet skin, wet bowels.

Lets look at the high-potency antipsychotics for just a second. While they do not have the side effects- the immediate side effects of the low-potency agents, they do have 3 very serious side effect possibilities.

What are these?

  • Extrapyramidal side effects, tardive dyskinesia, and NMS- Neuroleptic Malignant Syndrome.

What are the 3 extrapyramidal side effects that may accompany long term use of the high-potency antipsychotics?

  • Acute dystonia, drug-induced Parkinsonian syndrome, and akathesia.

We talked about acute dystonia and Parkinson’s in an earlier segment.

What is akathesia?

  • Strong feelings of inner restlessness; the patient has difficulty being still.

Tardive dyskinesia is an involuntary movement disorder. The patient cannot help moving certain parts. And what are these?

  • The tongue, the mouth, fingers, toes, as well as other parts. This particular characteristic of tardive dyskinesia- many involuntary mouth movements- chewing, smacking, licking of the lips, sucking motions, opening the mouth wide and wagging the tongue, facial grimaces.

Can almost any of the antipsychotics produce tardive dyskinesia?

  • Yes, they can, although the risk is much higher with the high-potency ones.

Which 2 lower-potency agents have very low risk of tardive dyskinesia?

  • Clozapine, Risperidone.

Trade name for Clozapine?

  • Clozaril.

And trade name for Risperidone?

  • Risperdol.

All of the antipsychotics, with the probable exception of 1, may produce Neuroleptic Malignant Syndrome While this is rare, it can be fatal.

What are the 4 characteristics of Neuroleptic Malignant Syndrome?

  • Severe muscle rigidity, fever, altered mental status, autonomic instability.

Which one of the antipsychotics appears to have little or no risk of causing Neuroleptic Malignant Syndrome?

  • Clozapine.

Trade name?

  • Clozaril.



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