I know that sodium thiopental already has with it a dilutent but had a question if someone could answer. Let's say you didn't already have the prepared dilutent. In Miller it says to dilute with sterile water or saline and to not use Lactated ringer's because it will solidify due to decrease in alkalinity and formation of crystalline free acid (again this is due to Lactated ringer's "acidity". ) However i am currently looking at a bag of saline and a bag of LR. The LR says pH 6 to 7.5. The 0.9% NaCl says pH 4.5 to 7. Therefore the saline bag is more acidic than the LR. This seems contradictory to Miller as well as what other text say. Anyone have any insight?
Thiopental reconstitution solutions
- Thread starter hotroddin
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I could be wrong, but I believe this is why.
The lack of buffering capacity in the NaCl means that the pH will readily fluctuate with the addition of a more acidic or more basic compound to reflect the pH of the added solution.
Lactate will act as a buffer to maintain a solution pH closer to the original pH of the LR which in this case is more acidic and therefore will precipitate the Thiopental.
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The lack of buffering capacity in the NaCl means that the pH will readily fluctuate with the addition of a more acidic or more basic compound to reflect the pH of the added solution.
Lactate will act as a buffer to maintain a solution pH closer to the original pH of the LR which in this case is more acidic and therefore will precipitate the Thiopental.
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I have a suggestion:
Try it!
Dilute it in saline and in LR and see what happens.
I think there will be no difference.
Try it!
Dilute it in saline and in LR and see what happens.
I think there will be no difference.
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I can definitively tell you that if you reconstitute thiopental in OR 11 in Seattle Washington at 20 degrees C under the prevailing conditions On the 20th of August 2009 at 1400 hours PDT, you will get a cloudy solution. 
If you reconstitute it in water and mix with an equal amount of LR, the resulting solution is not cloudy.
I do not want to run afoul of the pharmacy for wasting too many controlled substances today to see what happens with saline.
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If you reconstitute it in water and mix with an equal amount of LR, the resulting solution is not cloudy.
I do not want to run afoul of the pharmacy for wasting too many controlled substances today to see what happens with saline.
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Here is an image of today's experiment.
Thiopental reconstituted in LR on the left. Thiopental reconstituted with water and diluted 1:1 with LR on the right. Initially the LR solution was clearer than what you see here, but quickly became cloudy within a minute or two as it sat on the bench.
For those that do not use Thiopental routinely, the Thiopental syringe on the left is a clear glass syringe and is typically slightly clearer than the plastic syringe on the right. Thiopental typically has a yellowish tinge when reconstituted.
OK Class what did we learn from today's experiment?
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Thiopental reconstituted in LR on the left. Thiopental reconstituted with water and diluted 1:1 with LR on the right. Initially the LR solution was clearer than what you see here, but quickly became cloudy within a minute or two as it sat on the bench.
For those that do not use Thiopental routinely, the Thiopental syringe on the left is a clear glass syringe and is typically slightly clearer than the plastic syringe on the right. Thiopental typically has a yellowish tinge when reconstituted.
OK Class what did we learn from today's experiment?
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