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1. Drug Calculation mohammed alhabsi indanan, RN
2. sketch out of my talks Conversion
Methods of Calculation
Intravenous Flow rate Calculation
Continuous Infusion
Common Drug infusion & how they are given
Exercises
3. Conversion
Nanograms
Micrograms
Milligrams
Grams
Kilograms
ml
L
4. Methods of Calculation Basic Formula
Ratio & proportion
Fractional Equation
5. Basic Formula D = Desired dose
H = Dose on Hand
V = Vehicle-tablet or liquid
D
H
6. Basic Formula: Example:
Order – Dilantin 50mg orally TID
Drug Available-Dilantin 125mg/5ml
D=50mg H=125mg V=5ml
50 250
125 125
7. Ratio & proportion
8. Ratio & proportion HX = DV
DV
H
Order-Keflex 1gm orally TID
Drug Available-Keflex 250mg/capsule
D= 1gm (note: need to convert to mg)
H= 250mg
V= 1 capsule
9. Ratio & proportion:
10. Fractional Equation
Cross multiply & solve for X
11. Fractional Equation Order: Digoxin 0.25mg orally per day
Drug available: 0.125mg per tablet
D=0.25mg H=0.125mg V=1 tab
12. Intravenous Flow Rate Calculation Step 1- amount of fluid divided by hours to administer = ml/hr
Step 2- ml/hr x gtts/ml
60 min
Amount of fluid X gtts/ml___
hours to administer X min/hr
13. Intravenous Flow Rate Calculation 1000ml over 8 hrs
IV set= 15gtts/ml
Step 1:
Step 2:
14. Intravenous Flow Rate Calculation
1000 X 15 15000
8hrs X 60 480
15. Continuous Infusion calculation Note: always look 1st for DC
mg/min (Lidocaine, Pronestyl)
Desired dose X 60
Drug mg
Drug mg X cc/hr_____
Solution cc X 60 min/hr
16. Continuous Infusion calculation
17. Continuous Infusion calculation mcg/min (For example - Nitroglycerin)
Desired dose X 60
Drug mcg
Drug mcg X cc/hr____
Solution cc X 60min/hr
18. Continuous Infusion calculation
19. Continuous Infusion calculation mcg/kg/min
(Dopamine,Dobutamine,Nipride etc.)
A. To calculate cc/hr
20. mcg/kg/min
Dopamine 400mg/250ml D5W to start
at 5mcg/kg/min. weight is 86kg.
Look for Dilution Concentration…
400mg X 1000mcg = 400,000mcg
250ml
= 1600mcg/ml
Next step:
21. mcg/kg/min
Dopamine 400mg/250ml D5W to start
at 5mcg/kg/min. weight is 86kg.
5 X 86 X 60
1600
= 16.1ml/hr
22. mcg/kg/min
Dopamine 400mg/250cc D5W to start
at 5mcg/kg/min. weight is 86kg.
250cc_
400,000mcg
23. Continuous Infusion calculation mcg/kg/min
B. To calculate mcg/kg/min
Drug mcg/ X cc/hr________
Solution cc X 60min/hr X kg
24. Continuous Infusion calculation mcg/kg/min
Nipride 100mg/250cc D5 was ordered to
decrease BP. wt 143 lbs, IV pump is set at
25cc/hr. How many mcg/kg/min of Nipride is
the pt. receiving?
100,000mcgX25cc/hr 2,500,000
250ccX 60 X 65kg 975,000
25. Continuous Infusion calculation How to calculate mcg/kg/min if you know the rate of infusion?
Dosage in (mcg/cc/min)Xrate on pump
Patient’s weight in kg
Look 1st for dosage concentration for all drug calculation.
26. Look 1st for dosage concentration for all drug calculation 400mg of Dopamine in 250cc D5W
400,000mcg
250ml
1600mcg/ml
60min/hr
27. How to calculate mcg/kg/min if you know the rate of infusion? If you have a 75kg pt. for example…
26.6mcg/cc/min X 10ml on pump
Patient’s weight in kg (75kg)
= 3.5mcg/kg/min
29. Common Drug infusion & how they are given
30. Common Drug infusion & how they are given
31. LET’S DO SOME EXCERCISES.. 3 L of IV LR is charted over 12hrs. The drop factor is 15. the IV has been running for 9hrs. 800ml remains.
How many drops per minute are needed so that the IV finishes in the required time?
32. LET’S DO SOME EXCERCISES.. The doctor has decided to intubate your 100kg patient who has gone into acute respiratory distress. As the doctor prepares to intubate, he ask you to give 2.5mg/kg of propofol (10mg/ml) IVP. How many ml of propofol will you give?
33. LET’S DO SOME EXCERCISES.. A patient has daily fluid allowance of 1500ml. The patient has taken 30%. How many ml is this?
34. LET’S DO SOME EXCERCISES.. A child is prescribed erythromycin. The recommended dosage is 40mg/kg/day , 4 doses daily. If the child’s weight is 15kg, calculate the size of a single dose?
35. LET’S DO SOME EXCERCISES.. Dopamine 400mg in 250cc of D5W to infuse at 5mcg/kg/min. The patient’s weight is 200lbs. How many cc/hr would this be on an infusion pump?
36. LET’S DO SOME EXCERCISES.. The physician orders Ampicillin 500mg q6h orally (po). Ampicillin is available: 250mg capsule (cap). How many capsules would you administer q6h?
37. LET’S DO SOME EXCERCISES.. A 26 yr old man is to be given 2700ml of LR solution IV over a period of 18hrs. In addition, the amount of blood lost every 3hrs is to be replaced by packed RBC during the next 3hrs. Between the hours of 1000H & 1300H, the man lost 120ml. At what rate should fluid be delivered between 1300H and 1600H?
38.
MAGSUKUL….