<p>(edit, actually found the book text on Google books and paid a bit more attention to the context; the book is Kaplan &amp; Sadock's Concise Textbook of Clinical Psychiatry by Sadock, Sadock, and Ruiz, and you can find the specific passage by <a href="https://books.google.com/books?id=-PbZDQAAQBAJ&amp;pg=PT95&amp;lpg=PT95&amp;dq=&quot;levels+are+trough+levels+determined+in+the+morning+before+administration+of+the+morning+dose+of+medication&quot;" rel="nofollow noreferrer">searching for the quoted text</a>)</p>

<p>This book is talking about plasma concentrations of drugs. Based on the actual plasma concentrations for clozapine  with typical doses, this looks like just an error or typo: mL means milliliters, but these numbers would be more appropriate if they were in <em>nanograms</em> rather than milligrams, milligrams is several orders of magnitude too high and well beyond the solubility of clozapine in water.</p>

CC BY-SA 4.0
2018-10-23T10:48:46.760Z
Indeed, [from a review paper](https://www.ncbi.nlm.nih.gov/pubmed/22327098), _"The lowest effective clozapine levels ranged from 250 to 550 µg/L, while the recommended upper limit to prevent toxicity varied from 600 to 2000 µg/L [0.002 mg/mL]."_. That is a big error. :O
Steven Jeuris
CC BY-SA 4.0
2018-10-23T10:55:44.693Z
The [book I found](https://goo.gl/TU4Lu6) states "A therapeutic range for clozapine has not been established; however, a level of 100 nanograms per milliliter (ng/mL) is widely considered to be a minimum therapeutic threshold." This is not the same book the OP listed though, but based on it (Kaplan & Sadock's Concise Textbook of Clinical Psychiatry). Maybe they corrected it here, or it was an erroneous copy/paste/typo of the OP.
Steven Jeuris
CC BY-SA 4.0
2018-10-23T14:30:13.350Z
@StevenJeuris Might be correct in an earlier or later version but the one on Google Books I link to shows the same error as OP.
Bryan Krause
CC BY-SA 4.0
2018-10-23T14:49:46.907Z
Well, that only further confirms your answer! :)
Steven Jeuris
CC BY-SA 4.0
2018-10-16T21:15:17.810Z
2018-10-22T16:27:58.027Z
2018-10-22T16:27:58.027Z
Bryan Krause
<p>In the book <a href="https://rads.stackoverflow.com/amzn/click/078177327X" rel="nofollow noreferrer">Kaplan and Sadock's synopsis of psychiatry</a>:</p>

<blockquote>
  <p>Clozapine. Clozapine (Clozaril) levels are trough levels determined in
  the morning before administration of the morning dose of medication. A
  therapeutic range for clozapine has not been established; however, a
  level of 100 mg/mL is widely considered to be the minimum therapeutic
  threshold. At least 350 mg/mL of clozapine is considered to be
  necessary to achieve therapeutic response in patients with refractory
  schizophrenia. The likelihood of seizures and other side effects
  increases with clozapine levels greater than 1,200 mg/mL or doses
  greater than 600 mg per day or both. Clozapine is a common cause of a
  leukopenia in psychiatry. When moderate to severe leucopenia develops,
  clozapine treatment must be interrupted, but patients may be retreated
  with clozapine in the future.</p>
</blockquote>

<p>What is "mL" here?</p>

<p><sub>
Sadock, B. J., &amp; Sadock, V. A. (2011). <a href="https://rads.stackoverflow.com/amzn/click/078177327X" rel="nofollow noreferrer">Kaplan and Sadock's synopsis of psychiatry: Behavioral sciences/clinical psychiatry.</a> Lippincott Williams &amp; Wilkins.
</sub></p>

<psychiatry><psychopharmacology><schizophrenia><pharmacopsychiatry>
Unknown unit/mL
user2925716
# Unknown unit/mL

(Asked by: username_0 on 2018-10-16)

In the book [Kaplan and Sadock's synopsis of psychiatry](https://rads.stackoverflow.com/amzn/click/078177327X):

> Clozapine. Clozapine (Clozaril) levels are trough levels determined in
> the morning before administration of the morning dose of medication. A
> therapeutic range for clozapine has not been established; however, a
> level of 100 mg/mL is widely considered to be the minimum therapeutic
> threshold. At least 350 mg/mL of clozapine is considered to be
> necessary to achieve therapeutic response in patients with refractory
> schizophrenia. The likelihood of seizures and other side effects
> increases with clozapine levels greater than 1,200 mg/mL or doses
> greater than 600 mg per day or both. Clozapine is a common cause of a
> leukopenia in psychiatry. When moderate to severe leucopenia develops,
> clozapine treatment must be interrupted, but patients may be retreated
> with clozapine in the future.

What is "mL" here?

Sadock, B. J., & Sadock, V. A. (2011). [Kaplan and Sadock's synopsis of psychiatry: Behavioral sciences/clinical psychiatry.](https://rads.stackoverflow.com/amzn/click/078177327X) Lippincott Williams & Wilkins.

**Tags:** psychiatry, psychopharmacology, schizophrenia, pharmacopsychiatry


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## 1 answers

### Answer by username_1 on 2018-10-16. Score: 2

(edit, actually found the book text on Google books and paid a bit more attention to the context; the book is Kaplan & Sadock's Concise Textbook of Clinical Psychiatry by Sadock, Sadock, and Ruiz, and you can find the specific passage by [searching for the quoted text](https://books.google.com/books?id=-PbZDQAAQBAJ&pg=PT95&lpg=PT95&dq=))

This book is talking about plasma concentrations of drugs. Based on the actual plasma concentrations for clozapine with typical doses, this looks like just an error or typo: mL means milliliters, but these numbers would be more appropriate if they were in *nanograms* rather than milligrams, milligrams is several orders of magnitude too high and well beyond the solubility of clozapine in water.

> **Comments:**
> **username_2**: Indeed, [from a review paper](https://www.ncbi.nlm.nih.gov/pubmed/22327098), _"The lowest effective clozapine levels ranged from 250 to 550 µg/L, while the recommended upper limit to prevent toxicity varied from 600 to 2000 µg/L [0.002 mg/mL]."_. That is a big error. :O  
> **username_2**: The [book I found](https://goo.gl/TU4Lu6) states "A therapeutic range for clozapine has not been established; however, a level of 100 nanograms per milliliter (ng/mL) is widely considered to be a minimum therapeutic threshold." This is not the same book the OP listed though, but based on it (Kaplan & Sadock's Concise Textbook of Clinical Psychiatry). Maybe they corrected it here, or it was an erroneous copy/paste/typo of the OP.  
> **username_1**: @StevenJeuris Might be correct in an earlier or later version but the one on Google Books I link to shows the same error as OP.  
> **username_2**: Well, that only further confirms your answer! :)  

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