Drug Dosage & IV Rates Calculation Flashcards
Formula
(Amount Desired x Quantity) ÷ Amount on hand = Y (tablets required)
Toprol XL, 50 mg PO is ordered. Toprol XL is available as 100 mg per tablets. How many tablets would the nurse administer?
(50 mg x 1) ÷ 100 mg = 0.5 tablets
Dilantin 125 is available as 125 mg/5 ml. Dilantin 125, 0.3 g PO, is ordered. How much should the nurse administer to the patient?
0.3 g x 1000 = 300 mg
(300 × 5) ÷ 125 = 12 mL
Formula based on Body weight
First = Weight (kg) x Dosage Ordered (per kg) = Y (Required Dosage)
Then previous formula
Medrol 4mg/kg is ordered for a child weighing 64.8 Ib. Medrol is available as 500 mg/4mL. How many millilitres of medication must the nurse administer?
- 4 Ib ÷ 2.2 kg = 29.45 kg
- 5 kg x 4 mg/kg = 117.8 mg
(117. 8 mg x 4 mL) ÷ 500 = 0.942 mL
A doctor prescribes 250 mg of Ceftinnto be taken by 20.5 Ib infant every 8 hours. The medication label indicated that 75-150 mg/kg per day is the desired dosage range. Is this doctor’s order within the desired range?
Weight = 20.5 lb
Dosage ordered = 250 mg
Desired dosage range= 75 - 150 mg/kg
20.5 lb ÷ 2.2 = 9.32 kg
Minimum dosage = 9.32 kg x 75 mg/kg = 699 mg
Maximum dosage = 9.32 kg x 150 mg/kg = 1398 mg
24 hr ÷ 8 hr = 3
.:. Doctor orders medication to be give 3 times per day
Every dose is 250 mg
250 mg x 3 = 750 mg
Therefore, the doctor has ordered 750 mg of medication per day.
Yes it is within normal range. 699 > 750 < 1398
Intravenous Drop Rates formula
[Volume (mL) x Drop factor (gtts/mL)] ÷ Time (min) = Y (flow rate in gtts/min
Calculate the IV flow Rate for 250 mL of 0.5% dextrose to be administered over 180 minutes. The infusion set has a drop factor of 30 gtts/mL.
(250 ml x 30 gtts/mL) × 30 = 41.66 gtts/min
The infusion set is adjusted for a drop factor of 15 gtts/mL. Calculate the IV flow rate if 1500 mL IV saline is ordered to be infused over 12 hours.
12 h × 60 min = 180 min
(1500 mL x 15 gtts/mL) ÷ 180 min = 31.25
