Dosage Calculation Problem for Healthcare Professionals

Question

37) A 45 YO male weighing 65 kg is to receive tobramycin 2.5 mg/kg/dose IV every 12 hours for a severe infection. Each dose will be administered over 60 minutes.

a) How many mg will the patient receive each dose?

b) The pharmacy sends over the appropriate dose of tobramycin in a 100 mL bag of NS. At what rate will you set the IV infusion pump?

Wojcik, Bradley J.. Nursing Dosage Calculation Workbook: 24 Categories Of Problems From Basic To Advanced! (Dosage Calculation Success Series) (p. 50). Nurse Superhero. Kindle Edition.

Answer 1

a) To find this answer, we multiply the patient’s weight in kg by the dose of mg/kg:

65 x 2.5 = 162.5 mg of tobramycin per dose

b) IV pumps can only be set for hourly rates. To find the infusion rate, we use the formula

volume (in mL)/time (in hours)

volume = 100 mL

time = 60 minutes = 1 hour

100/1 = 100

So you would set the pump at 100 mL/hr

The 12 hours refers to the frequency of the medication (part of the “rights” of medication administration). It does not factor into the rate of infusion.

Answer 2

a). 65 kg x 2.5 mg/kg/dose = 162.5 mg each dose

b). 100 mL/12 hrs = 8.33 mL/hr = 0.139 mL/min (set pump depending on units of time)