Saturday, December 5, 2015

Dosage Calculation - Mass/Liquid For Liquid Questions

Source Website: http://www.dosagehelp.com/liquid.html
By DosageHelp.com


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

 
Formula:  


     
          
            
              Ordered
              Have
           
           x
           Volume Per Have
           =
           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?

         
            
              Ordered
              Have
           
           x
           Volume Per Have
           =
           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


         
           
              100 mg
              30 mg
           
           x
           5 mL
           =
           
             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?

         
            
              Ordered
              Have
           
           x
           Volume Per Have
           =
           Y(Liquid required)
        

         
            
              40 mg
              80 mg
           
           x
           1 mL
           =
           
             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


         
           GIVE:
           
             
          
          mL
        

         
            
              Ordered
              Have
           
           x
           Volume Per Have
           =
           Y(Liquid required)
        

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




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