Saturday, January 2, 2016

Dosage Calculation - Dosage By Weight Questions

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


Dosage By Weight Questions
Given the weight of a patient and a dosage specified in terms of weight, calculate the necessary dosage. These problems are a type of pediatric dosage calculations.
Formula:


    
         
             Weight in Kg
             x
             Dosage Per Kg
             =
             Y(Required Dosage)
        
  

Example: A doctor orders 200 mg of Rocephin to be taken by a 15.4 lb infant every 8 hours. The medication label shows that 75-150 mg/kg per day is the appropriate dosage range. Is this doctor's order within the desired range?

         
             Weight in Kg
             x
             Dosage Per Kg
             =
             Y(Required Dosage)
        
Convert 15.4 lb to kg.
    lb → kg    ( ÷ by 2.2 )
    15.4 lb ÷ 2.2 = 7 kg

7 kg x 75 mg/kg = 525 mg (Minimum Desired Dosage)
7 kg x 150 mg/kg = 1,050 mg (Maximum Desired Dosage)
24 hours in one day and the medication is ordered every 8 hours.

    24 hrs / 8 hrs = 3 times per day doctor ordered medication
    200 x 3 = 600 mg ordered per day
    600 mg is within the desired range of 525-1,050 mg


         
             
               Yes
            
             doctor has ordered a dosage within the desired range.
         

Example: Solumedrol 1.5 mg/kg is ordered for a child weighing 74.8 lb. Solumedrol is available as 125 mg / 2mL. How many mL must the nurse administer?

         
             Weight in Kg
             x
             Dosage Per Kg
             =
             Y(Required Dosage)
        
Convert 74.8 lb to kg.
    lb → kg    ( ÷ by 2.2 )
    74.8 lb ÷ 2.2 = 34 kg


         
             34 kg
             x
             1.5 mg/kg
             =
             51 mg
        
This is now an ordinary Mass/Liquid For Liquid Question. 51 mg is ordered and the medication is available as 125 mg / 2 mL.

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

         
            
              51 mg
              125 mg
           
           x
           2 mL
           =
           
             0.82 mL
           
        
Alternatively, 125 mg = 2mL
Therefore 51 mg = 2/125 x 51 = 0.82 mL


Question (6): (From Ngee Ann Polytechnics Dosage Calculation Worksheet)
ORDER: Drug G 5 mg per kg body weight P.O.
AVAILABLE: Drug G 250 mg per 5 mL
BODY WEIGHT: 500 kg


         
           GIVE:
           
             
          
          mL
        

         
             Weight in Kg
             x
             Dosage Per Kg
             =
             Y(Required Dosage)
        

         
             50 kg
             x
             5 mg/Kg
             =
             250 mg
        

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

         
            
              250 mg
              250 mg
           
           x
           5 mL
           =
           
             5 mL
           
        
Alternatively, 250 mg = 5 mL
Therefore 250 mg = 1/250 x 250 = 5 mL


Question (10): (From Ngee Ann Polytechnics Dosage Calculation Worksheet)
ORDER: Drug N 15 mg per kg body weight P.O.
AVAILABLE: Drug N 60 mg per mL
BODY WEIGHT: 100 kg


         
           GIVE:
           
             
          
          mL
        

         
             Weight in Kg
             x
             Dosage Per Kg
             =
             Y(Required Dosage)
        

         
             100 kg
             x
             15 mg/Kg
             =
             1,500 mg
        

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

         
           
              1,500 mg
              60 mg
           
           x
           1 mL
           =
           
             25 mL
           
         
Alternatively, 60 mg = 1 mL
Therefore 1,500 mg = 1/60 x 1,500 = 25 mL

 
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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

[5] MathML Fundamentals (Colours), W3C recommendation, http://www.w3.org/TR/MathML/chapter2.html