doctor prescribed pepcid 20 mg ivpb hs. on hand 4 ml vial contains 10 mg/ ml. how much med should be added to piggyback?
doing a little math here to determine the total amount of medication you have on hand in the 4 ml vial, i multiplied (10 mg/1 ml) x 4 ml to get 40 mg/4 ml
. using that figure to plug into the formula, dose desired divided by dose on hand, you get a number that has a fraction in the denominator. multiplying the top and bottom of this complex fraction by the reciprocal of the fraction in the denominator, you end up with this equation which gives you the answer to this part of the question:
20 mg/1 (dose desired) x 40 ml/40 mg (dose on hand) = 2 ml (after doing the math and canceling labels)
the manufacturer's instructions for ivpb admin recommend that the pepcid be added to 50 ml of d5/w and infused over 60 minutes. the drop factor of the ivpb tubing is 60 gtt/ml. how many drops per minute should be infused to deliver the required amount of drug in 60 minutes?
by using dimensional analysis, again, or the factor label method, you set this problem up with the objective of ending up with these labels on the resulting answer: gtts/min
. first you do some simple addition to determine the total amount of solution you have to infuse:
50 ml of d5w + 2 ml of pepcid = 52 ml (total solution to be infused)
here's how you calculate the drip rate:
52 ml (total solution to be infused)/60 minutes (total times to be infused) x 60 gtts/1 ml (drip factor of iv tubing being used) = 52 gtts/minute (infusion drop rate)