Dosage Calc!! I don't understand.

  1. Im so confused! Heres the question

    Order: Furadantin oral suspension 25 mg po q6h for a child weighing 17kg
    On hand: Furadantin 25 mg per teaspoon
    Manufacture recc: 0.75-1.75 mg/kg/q6h

    Is this a safe dose?

    Heres where Im getting stuck. It says the answer is safe but I dont understand why and how!

    I did this

    17kg X 1.75mg/1kg= 29.75mg--- 29.75mg / 4 (doses in 24 hours) = 7.44 mg/q6h high end or max

    17kg x 0.75mg/1kg = 12.75mg--- 12.75mg / 4 (doses in 24 hours) = 3.19 mg/q6h low

    range is then 3.19-7.44 mg/q6h

    looking back at the order, Dr ordered 25 mg po q6h, then looking at range this is far to high? However it says its safe? WHAT AM I DOING WRONG! Im extremely frustrated.
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    About miss.martz

    Joined: Mar '17; Posts: 14; Likes: 2


  3. by   Wuzzie
    You're adding an incorrect step. You started out just fine and got the answer. Why did you divide by four? The safe dose is 0.75-1.75 mg/kg/Q6 HOURS. The dose ordered is every 6 hours. You're over thinking this. Look at it again. I don't want to straight out tell you because you'll retain it better if you figure it out yourself.
  4. by   Susie2310
    You arrived at the 29.75 mg dose by multiplying the maximum end of the manufacturer's recommended dose range (1.75 mg) by the child's weight (17kg). As Wuzzie said, you have added an incorrect step by dividing the 29.75 mg by 4. Look again at how often the medication is ordered to be given (q 6 hours), and look again at the time period specified by the manufacturer at which the medication is to be given (q 6 hours). You have already calculated the maximum dose that can be given at six hourly intervals according to the manufacturer's recommendations (29.75 mg). The doctor's order is for 25 mg q 6 hours, so the ordered dose is within the range specified by the manufacturer (29.75 mg q 6 hours is the outer limit of the manufacturer's dose range), which is why you were told the doctor's order is a safe dose.
    Last edit by Susie2310 on Aug 12, '17
  5. by   Wuzzie
  6. by   ~♪♫ in my ♥~
    Quote from miss.martz
    17kg X 1.75mg/1kg= 29.75mg--- 29.75mg / 4 (doses in 24 hours)

    17kg x 0.75mg/1kg = 12.75mg--- 12.75mg / 4 (doses in 24 hours)
    You added in the 4 doses part... the mfr recommendation says xxx mg/kg/q6h... which is what you calculated before you arbitrarily divided it by 4.

    If you were actually using units rather than simply implying them, you'd have:

    29.75 mg / (4 doses/24 hr) which would give you units of mg*hr/doses... which is pretty nonsensical...
  7. by   ~♪♫ in my ♥~
    Quote from Wuzzie
    Wasn't it "Bueller?"
  8. by   Wuzzie
    Quote from KindaBack
    Wasn't it "Bueller?"
    Sorry, my bad.
  9. by   ~♪♫ in my ♥~
    Quote from Wuzzie
    Sorry, my bad.
    I was in college (the first time) when it came out and we binged on it... then they brought it to the university and we binged on it again... then it came out on VHS and we had a truly epic theme party.

    A truly timeless movie from a simpler time.
  10. by   soutthpaw
    OP is mistaking mg/kg/DAY with mg/kg/DOSE!