Chuck Oates

APPM 1313-02

20 March 2010

Math for Health Careers

Oklahoma City Community College




Solved Drip Rate Problem with

Drug Infusion Rate (Weight Flow Rate) Ordered



On p. 172 #3a, the trick is that the label states the  250 mg / 5 mL  strength in "do it yourself" form, that is 5 mL of diluent added to the 250 mg vial of medication.  Once that's determined, the rest is easy:


150 mg   x   5  mL


                250 mg


     150  x  5

= ----------------  mL




=  3/5  x  5   mL



=  3  mL




For p. 174, #8,  they've asked for a flow rate of  5 mg / hr .  That's a WEIGHT flow rate, so we're going to need the concentration of the medication in the "big bag/bottle" as a conversion factor.  Let's calculate that now.


100 mg  / 500 mL    is the required concentration.


Now, if we start with 5 mg / hr,  we'll need to convert that to  gtt/min.  Let's try it.


First, we'll change the time units from hr to min.


1 hr       x     5 mg


60 min   x     1 hr



Now we're in mg/min, so it's time to apply the concentration in the big bag ....



1 hr       x     5 mg   x   500 mL


60 min   x     1 hr     x   100 mg



That's transformed the unit to mL/min, but we need gtt/min, so we'll apply the drop factor, 60 gtt/mL ...



1 hr       x     5 mg   x   500 mL    x   60 gtt


60 min   x     1 hr     x   100 mg    x    1 mL



Now we're in gtt/min and the arithmetic looks like



5  x  500  x  60          gtt

----------------------    ----

     60  x  100              min



=  25 gtt/min



Let me know if you get stuck again, or if you need clarifications of the stuff above.  I hope this helps!


Enjoy(?) the snow!


Prof. Oates

Charles L. "Chuck" Oates
e-mail:  C h u c k  <AT>  C h u c k O a t e s <DOT> c o m