Perplexed by med calculation

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Hi everybody,

Can someone help me with this problem.

Sodium Seconal capsules are labeled 100 mg. How many will be administer if the order is for gr 1 1/2?

The order is for 90 mg, gr is 60 mg x 1.5. My on hand is 100 mg. Would I give 1 tablet, because 100mg divided by 90 mg is 1.1? This problem is off my practice worksheet. The answer is 1 tablet but they had 100 mg desired, 100 mg on hand, how is that? Can anybody explain this to me?

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Specializes in Hospitalist Medicine.

I'm confused by the wording of your question. What do you mean by "order is for gr 1 1/2"? Do you mean grams? Or grains?

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While most people equate 60 mg to gr 1, the actual conversion is 64.799 mg. Using this conversion factor gr 1.5 is actually 97.169 mg. The good news is that after you finish school and start your nursing career, it is likely that you will never see another order using apothecary units of measure

Regarding the number of capsules for a particular dose, most medications use standard dosing for adults (e.g., acetaminophen 500, 650, or 1000 mg). If it is a medication that is weight based the ordered dose might have to be adjusted based upon formulation available.

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Your division is backwards. It should be 90 mg divided by 100 mg. You know, doc over stock. It would then be 0.9 of a tablet, which doesn't add up to 100 mg. Are there any steps that have been left out?

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Yes this is all the steps. So it is 0.9 of a tablet. So I give 1 tablet.

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