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# How would I convert mg to mL?

Hello! I am trying to convert mg to mL. Does anyone know the formula that I should use to solve this? This is a question out of my text book.

Example: Doctor's order reads: Ampicillin 375 mg PO q8h. You have Ampicilling liquid 125mg per 5 mL. How many mL would you give?

### 20 Answers

- MarieLv 61 decade agoFavorite Answer
The previous answerer (the pharmacist) is giving you the correct way to solve for the problem, but do also realize that you are NOT converting milligrams to milliliters. There is no way to do that; milligrams are a measure of mass and milliliters are a measure of volume.

What you are trying to do is to figure out how many milliliters of suspension are needed to give you the appropriate amount of the drug. They tell you how many milligrams of ampicillin are in 5 mL. So all you have to do is figure out how many mL are needed. Don't think of it as a conversion problem, or you'll get more mixed up. It would be the same thing as if they asked "If you need to take 375 mg of ampicillin and all you have are 125 mg pills, how many do you take?"

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- karstenLv 43 years ago
Mg To Ml Conversion

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- 1 decade ago
First response is wrong.

The response from the retired pharmacist is correct. You can set up a proportion and find how many mLs are needed, or you can approach it by finding the number of mg per single mL in the suspension. 125mg PER 5mL means that each mL contains 25mg. Then divide 375mg by 25mg/mL to find the number of mLs per dose.

This method is a proportion but many find it easier to work it out in this manner as many are not the best with math.

When ever you do this kind of calculation think about your answer. For example, response #1 said it was 1.6mL or something, if you give 1.6mL of a suspension that is 25mg PER mL you are not giving anywhere near the correct dose.

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- 3 years ago
A doctor orders calls for a patient to receive a 450 mg ampicillin .the liquid suspension on hand indicate an ampicillin solution with a specific gravity of 0.05 . What volume, is in mL,should be administered to the patient?

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- Anonymous4 years ago
35MG IN 355 ML

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