check my work for this IV question please - page 2

drug order: cefoxitin 1 mg every 8 hours for 6 days. the available vile has 2 mg of powder, which you are to reconstitute in 20 ml of sterile water. the reconstituted volume is 21 ml. you are to... Read More

  1. by   KelRN215
    I really can't stand med math problems like this. Who writes these questions? 1 mg of cefoxitin isn't even an appropriate dose for an infant (pediatric doses are 80-160 mg/kg/day for an acute infection) and cefoxitin would typically be administered IVP in an adult.

    Are you sure it's not 1 GRAM of cefoxitin and a 2 gram vial? It doesn't actually change your math but I'm not a fan of these types of nonsensical scenarios.
  2. by   thatgirl2478
    So - 2 questions:

    If you're instructed to give a drug every 8 hrs, isn't that 4 doses in 24 hours (first dose, then 3 subesquent doses 8 hrs apart = 24 hrs)?

    Second - in the example, if you reconstitute 2mg but are only supposed to give 1, does the other 1mg just get wasted? Or can it be used for the next dose? Seems really wasteful to toss it... (but there's probably a reason).

    Not a nurse yet. I start my BSN in 2019.
  3. by   KelRN215
    Quote from thatgirl2478
    So - 2 questions:

    If you're instructed to give a drug every 8 hrs, isn't that 4 doses in 24 hours (first dose, then 3 subesquent doses 8 hrs apart = 24 hrs)?

    Second - in the example, if you reconstitute 2mg but are only supposed to give 1, does the other 1mg just get wasted? Or can it be used for the next dose? Seems really wasteful to toss it... (but there's probably a reason).

    Not a nurse yet. I start my BSN in 2019.
    1. No. If you give the first dose at say 4pm, you would give subsequent doses at 12am and then 8am. 4pm tomorrow is the start of a new 24 hr period. In theory if you were rescheduling the doses to get the patient on, say, a 7a-3p-11p schedule yes he'd end up getting 4 doses in 24 hrs but don't overthink things. When a question asks how many doses a patient will receive in 24 hrs, they want you to divide 24 hrs by the ordered frequency.

    2. If it's something that needs to be reconstituted on the floor, the remainder of the vial would be wasted. In the pharmacy, they could draw 2 doses out of the same vial under a sterile compounding hood. In general, meds are only reconstituted on the floor if there are stability issues. Another reason why this problem is a dumb question the way it's written- cefoxitin doesn't have stability issues and would be mixed in the pharmacy in a syringe to be administered IVP. (I suppose it's possible that if you worked in a small hospital or somewhere that doesn't have a pharmacy on site, you could be mixing this drug on the floor but that doesn't seem likely to me. I know my infusion pharmacy mixes IV drugs for a few SNFs that don't have pharmacies on site.)
  4. by   thatgirl2478
    Thank you for the thorough answer! Very helpful!
  5. by   KrCmommy522
    Here is how I did my calculations:

    Your order is for 1 mg to be reconstituted in 20 mL of sterile water. The reconstituted volume is 21 mL. So, the available dosage is 2 mg/21 mL. So, you calculate how many mL of cefoxitin should be ADDED to the 50 mL secondary bag.

    How many mL should of cefoxitin should be ADDED to the 50 mL secondary bag?

    Order: 1 mg q8h x 6 days
    Available: 2 mg/21 mL

    1 mg x 21 mL/2 mg = 10.5 mL

    Draw up 10.5 mL of reconstituted med from the vial.

    Now, you are to administer this medication IVPB in 50 mL of D5W. So, you are ADDING 10.5 mL to the 50 mL bag of D5W, so:
    50 mL of D5W + 10.5 mL of reconstituted med = 60.5 mL total

    Now, the question is for drop/min rate to admin the med in 20 min:
    So, do you use the 60.5 mL or the original 50 mL? Since the med is mixed in the 50 mL bag, you are hanging a bag with 60.5 mL in it, so that is what you should base the volume on.

    60.5 mL/20 min x 10 gtt/mL = 605/20 = 30.25 = 30 gtt/min

    Hope this helps!
  6. by   HarleyGrandma
    Quote from thatgirl2478
    Second - in the example, if you reconstitute 2mg but are only supposed to give 1, does the other 1mg just get wasted? Or can it be used for the next dose? Seems really wasteful to toss it... (but there's probably a reason).

    Not a nurse yet. I start my BSN in 2019.
    You are going to be *amazed* at how much medication gets wasted! And how much time is spent wasting it, getting a second nurse to sign off, and documenting it all.
  7. by   thatgirl2478
    Quote from HarleyGrandma
    You are going to be *amazed* at how much medication gets wasted! And how much time is spent wasting it, getting a second nurse to sign off, and documenting it all.
    You have to wonder if there isn't a better way for the hospitals/drug manufacturers to package stuff to make it less wastefull. I mean, isn't controlling costs HUGE these days? LOL

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