Pharmacy Rx

 

             3 METHODS TO CALCULATE DOSAGES WHEN DRUG STRENGTH IS NOT AVAILABLE

 

 

                                                               

 

 

 

 

 

                                                  DIMENSIONAL ANALYSIS (DA) METHOD

 

 

EX) DOCTOR ORDERS: 0.05 MG PO

AVAILABLE: 25 MCG TAB

 

 

*START OFF BY REVIEWING WHAT KIND OF DOSAGE FORM YOU ARE GOING TO CALCULATE*

 

TAB =

TAB = 1 TAB

          25 MCG

 

TAB = 1 TAB     1000 MCG   0.05 MG                   *THIS EQUATION IS TO CONVERT MG TO MCG

         25 MCG X    1 MG    X    1 TAB

 

TAB = 1 TAB     1000 MCG   0.05 MG                *CANCEL UNITS OF MEASURE

        25 MCG X    1 MG    X    1 TAB

                 

                     DO MATH

TAB =  1 TAB     1000           0.05          1 X 1000 X 0.05         50

               25    X     1        X    1 TAB  =     25 X 1  X  1       =        25   =  2 TABS

 

 

                                                                 BASIC  FORMULA  METHOD

 

   D (DESIRED DOSE) X  Q (QUANITY) = X                                                                         

   A (AVAILABLE)                                                                                                          

                                                                                                                                      

EX) ORDER: 0.05 MG PO                                                                               

AVAILABLE: 25 MCG TAB     

                                                                     

            0.05 MG    X   1 TAB = 0.002                                                                                         

               25 MCG

 

CONVERT 0.002 TO MG

0.002 x 1000 = 2 TABS

 

 

    

                                                                       RATIO AND PROPORTION METHOD

 

 

 DOCTOR ORDERS:   0.05 MG PO

 AVAILABLE:   25 MCG TAB

 

  

    IF          25 MCG          1 TAB

  THEN   0.05 MG   =     X TAB    ------------<    0.05 x 1 / 25 = 0.002

 

*CONVERT MCG TO MG

 

0.002 X 1000 = 2 TABS