Dosage Calculation - Mass/Liquid For Liquid Questions

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Mass/Liquid For Liquid Questions
Given an amount of mass per liquid, how much liquid do you require?
 
Formula:  

$$\boxed{\frac{\mathbf{Ordered}}{\mathbf{Have}}x\mathbf{Volume\; Per\; Have}=\mathbf{Y(Liquid\; required)}}$$

Example: Phenytoin (Dilantin), 0.1 g PO, is ordered to be given through a nasogastric tube. Phenytoin is available as 30 mg / 5 mL. How much would the nurse administer?

$$\frac{\mathbf{Ordered}}{\mathbf{Have}}x\mathbf{Volume\; Per\; Have}=\mathbf{Y(Liquid\; required)}$$

Convert 0.1 g to mg.
    mcg ← mg ← g ← kg    ( x by 1,000 )
    0.1 g x 1,000 = 100 mg

$$\frac{\mathbf{100\; mg}}{\mathbf{30\; mg}}x\mathbf{5\; mL}=\boxed{\mathbf{16.7\; mL}}$$

Alternatively, 30 mg = 5 mL
Therefore 100 mg = 5/30 x 100 = 16.67 mL

Example: Ordered Lasix 40 mg IV push now. Available: 80 mg in 1 mL. How much will the nurse draw up?

$$\frac{\mathbf{Ordered}}{\mathbf{Have}}x\mathbf{Volume\; Per\; Have}=\mathbf{Y(Liquid\; required)}$$

$$\frac{\mathbf{40\; mg}}{\mathbf{80\; mg}}x\mathbf{1\; mL}=\boxed{\mathbf{0.5\; mL}}$$

Alternatively, 80 mg = 1 mL
Therefore 40 mg = 1/80 x 40 = 0.5 mL

Example: (From Ngee Ann Polytechnics Dosage Calculation Worksheet)
ORDER: Drug A 100,000 units P.O.
AVAILABLE: Drug A 1,000,000 units per 20 mL

$$\mathbf{\text{GIVE:}}\underline{}\mathbf{\text{mL}}$$

$$\frac{\mathbf{Ordered}}{\mathbf{Have}}x\mathbf{Volume\; Per\; Have}=\mathbf{Y(Liquid\; required)}$$

$$\frac{\mathbf{100,000\; units}}{\mathbf{1,000,000\; units}}x\mathbf{20\; mL}=\boxed{\mathbf{2\; mL}}$$

Alternatively, 1,000,000 units = 20 mL
Therefore 100,000 units = 20/1,000,000 x 100,000 = 2 mL

Continue (Go to Mass/Liquid for Liquid Questions (2))

Reference
[1] Advanced Formatting, Ry’s MathML Tutorial, http://rypress.com/tutorials/mathml/advanced-formatting.
[2] MathML, Presentation MathML, https://en.wikipedia.org/wiki/MathML.
[3] MathJax in Blogger (II), Posted on Tuesday, 12 July 2011, http://irrep.blogspot.sg/2011/07/mathjax-in-blogger-ii.html
[4] MathJax, http://docs.mathjax.org/en/latest/start.html

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