3. A. Understanding the
Abbreviations
Abbreviations English meaning
o.d. every day/ once a day
b.i.d, B.I.D. twice a day
t.i.d, T.I.D. three times a day
q.i.d., Q.I.D. four times a day
q.h. every hour
q2h every 2 hours
q3h every 3 hours
caps. capsule
tab. tablet
tsp. teaspoon
gtts drop
3
Abbreviations English meaning
IM intramuscularly
IV, I.V. intravenously
S.C., s.c., sub q subcutaneouly
S.L. sublingually
p.o. by mouth (per os)
p.r.n., PRN
as the occasion arises,
when needed or requested
a.c. before meal
p.c. after meal
stat immediately
4. Understanding the Abbreviations
Abbreviations English meaning
ml, mL milliliter (1/1000 L)
dl, DL deciliter (1/10 L)
L liter
mg milligram (1/1000 g)
g gram (1/1000 kg)
kg kilogram
4
7. Examples:
1. 7.5g =___________mg
7
2. 2000mg=_________g
3. 2.5kg=_________g
4. 0.5L=_________mL
5. Digoxin tablets are presented as 125 micrograms. What is this in milligram?
125 micrograms = __________ mg
B. Values conversion
8. Examples:
1. 7.5g =___________mg
8
7500
2. 2000mg=_________g
3. 2.5kg=_________g
4. 0.5L=_________mL
5. Digoxin tablets are presented as 125 micrograms. What is this in milligram?
125 micrograms = __________ mg
B. Values conversion
9. Examples:
1. 7.5g =___________mg
9
7500
2. 2000mg=_________g
2
3. 2.5kg=_________g
4. 0.5L=_________mL
5. Digoxin tablets are presented as 125 micrograms. What is this in milligram?
125 micrograms = __________ mg
B. Values conversion
10. Examples:
1. 7.5g =___________mg
10
7500
2. 2000mg=_________g
2
3. 2.5kg=_________g
2500
4. 0.5L=_________mL
5. Digoxin tablets are presented as 125 micrograms. What is this in milligram?
125 micrograms = __________ mg
11. Examples:
1. 7.5g =___________mg
11
7500
2. 2000mg=_________g
2
3. 2.5kg=_________g
2500
4. 0.5L=_________mL
500
5. Digoxin tablets are presented as 125 micrograms. What is this in milligram?
125 micrograms = __________ mg
B. Values conversion
12. Examples:
1. 7.5g =___________mg
12
7500
2. 2000mg=_________g
2
3. 2.5kg=_________g
2500
4. 0.5L=_________mL
500
5. Digoxin tablets are presented as 125 micrograms. What is this in milligram?
125 micrograms = __________ mg
0.125
B. Values conversion
19. Interpretations
Example 3:“2 mg morphine sulfate IV stat. 1-2mg q1-2h IV prn pain”
19
Interpretations: Give 2 mg of morphine sulfate intravenously
immediately, and then give 1 or 2 mg of morphine sulfate
intravenously every 1-2 hours intravenously as needed for pain.
21. D. Dosage calculations
21
Amount of liquid to give =
Want
Have
x Liquid
Formula 2:
OR
Concentration = Mass / Volume
( For injection
in Liquid form)
Volume
Volume of drug
22. Examples:
There are Panadol 30mg/caps, you need to administer 120mg of Panadol,
how many capsule is needed?
22
23. Examples:
There are Panadol 30mg/caps, you need to administer 120mg of Panadol, how many
capsule is needed?
23
Number of tablets to give = 120 mg
30 mg/caps
= 4 capsule
24. Examples:
Heparin 2000 units subcutaneously is prescribed, you have 5000 units/mL, what is the
volume of heparin you need to inject?
24
25. Examples:
Heparin 2000 units subcutaneously is prescribed, you have 5000 units/mL, what is the
volume of heparin you need to inject?
25
Amount of liquid = Want
Have
Amount of liquid = 2000 units
5000 units
= 0.4 mL
x Liquid
2000 units
5000 units/mL
x 1 mL OR
26. Examples:
The stock contains meperidine 100mg/mL, and you have to administer 50mg IM. What is
the amount of meperidine you need to pull up into a syringe?
26
27. Examples:
The stock contains meperidine 100mg/mL, and you have to administer 50mg IM. What is
the amount of meperidine you need to pull up into a syringe?
27
Amount of liquid = Want
Have
x Liquid
Amount of liquid = 50 mg
100 mg/mL
= 0.5 mL IM
29. Examples:
You have Dextromethorphan 3.5mg/5mL, now you want 10.5mg, determine how many
teaspoon should be administered?
29
Volume to give =
Want
Have
Volume to give = 10.5 mg
3.5mg/5mL
= 15mL
Because 5mL = 1teaspoon, thus 15 mL/(5 mL/teaspoon)= 3 teaspoons
32. Examples:
You have ampicillin 250mg/tsp, now you want ampicillin 500mg, how many teaspoons do
you need?
32
500 mg
? tsp
=
250 mg
1 tsp
You need 2 teaspoons
33. Examples:
Ampicillin oral suspension contains 250 mg of the drug in each 5 mL. How many milliliters
would be measured into a medication syringe to obtain a dose of 75mg of ampicillin?
33
34. Examples:
Ampicillin oral suspension contains 250 mg of the drug in each 5 mL. How many milliliters
would be measured into a medication syringe to obtain a dose of 75mg of ampicillin?
34
5 mL
250 mg
x mL
75 mg
= OR 5: 250 = x: 75
X = 1.5mL
35. E. Calculation of Dosage according to body weight
Dosage administered= weight (kg) x dose
35
36. Examples:
A patient weighted 80 kg is prescribed 10 mg/kg/hr of a drug. How many milligrams per
hour of the drug does the patient need?
36
37. Examples:
A patient weighted 80 kg is prescribed 10 mg/kg/hr of a drug. How many milligrams per
hour of the drug does the patient need?
37
Dosage = weight (kg) x dose
= 80kg x 10 mg/kg/hr
= 800mg/hr
38. Examples:
A patient weights 68 kg. A drug is prescribed as 60 mg/kg/day, q.i.d. There are 500mg
capsules in the stock, how many capsules should be administered each time?
38
Dosage = weight (kg) x dose
= 68 kg x 60 mg/kg/day
= 4080 mg/day
Single Dose = 4080 / 4 =1020 mg/dose
= 1020 / 500 capsules ≈ 2 capsules
39. Examples:
The health care provider prescribes aspirin chewable tablets for a 110 lbs child. The
recommended dosage for aspirin is 20mg/kg per dose. How many 0.5g tablets of the drug
should be given to this patient for each dose.
39
40. Examples:
The health care provider prescribes aspirin chewable tablets for a 110 lbs child. The
recommended dosage for aspirin is 20mg/kg per dose. How many 0.5g tablets of the drug
should be given to this patient for each dose.
40
Child weight: 110 / 2.2 = 50 kg
The wanted dose = 50 x 20 = 1000 mg
The tablets required = 1/0.5 = 2 tablets
= 1g Remember to convert to
the same measurements
42. IV calculations
IV prescription should include:
The total volume to be infused
The length of time the IV should run (in hours)
Tubing have particular drop factors (drops per minute)
- controlled using the control slide on the tubing
42
43. IV calculations
43
Formula 4:
Flow rate (drops per minute)
=
Volume (mL)
Time (minutes )
x Drop Factor (drops/ mL)
(gtts / min)
(gtts / mL)
Or Drip rate
44. Drop Factor
The tubing have different Drop Factor (gtts / mL):
10 / 15/ 20 /60
i.e. Drop factor 10 = 10 gtts / mL
Drop factor 15 = 15 gtts / mL
Drop factor 20 = 20 gtts / mL
Drop factor 60 = 60 gtts / mL
44
45. IV calculations example
Sodium chloride is prescribed of 500 mL in 4 hours i.v. , you
see the label information on the administration set and find
that the drop factor is 15.
45
46. IV calculations example
46
Step 1, count how many mL should be infused in 1 minutes.
Volume to be infused in 1 minute = 500 mL / 4 hrs = 125
mL/hrs
= 125 /60 = 2.08 mL/min
Sodium chloride is prescribed of 500 mL in 4 hours i.v. , you
see the label information on the administration set and find
that the drop factor is 15.
47. IV calculations example
Sodium chloride is prescribed of 500 mL in 4 hours i.v. , you see the label information on the
administration set and find that the drop factor is 15.
47
Step 1, count how many mL should be infused in 1 minutes.
Volume to be infused in 1 minute = 500 mL / 4 hrs = 125 mL/hrs
= 125 /60 = 2.08 mL/min
Step 2, Drops per minute
=
Volume (mL)
Time (minutes )
x Drop Factor (drops/ mL)
Drops per minute
=
2.08 mL/min x 15
Drops per minute 31.25 gtts / minute
round to 31 gtts/minute
=
48. Example
An IV infusion of 1000 mL is prescribed to run for 6 hours. What is the volume to be infused in 1
hour?
48
49. Example
An IV infusion of 1000 mL is prescribed to run for 6 hours. What is the volume to be infused in 1
hour?
49
Volume to be infused in 1 hour = 1000 / 6
= 166 mL / hr
50. Example
An IV infusion of 1000 mL is prescribed to run for 6 hours. What Flow Rate should be
infused with a drop rate= 10?
50
51. Example
An IV infusion of 1000 mL is prescribed to run for 6 hours. What Flow Rate should be
infused with a drop rate= 10?
51
Volume to be infused in 1 hour = 1000 / 6
= 166 mL / hr
Flow rate (Volume to be infused in 1 minute) = 166/60 = 2.767 mL / min
= 2.767 x 10 = 27.67 gtts / min
round to 28 gtts / min
(7 gtts / 15 seconds)
52. Example
An IV infusion of 1000 mL is prescribed to run for 6 hours. What Flow Rate should be
infused with a drop rate= 10?
2020 52
Volume to be infused in 1 hour = 1000 / 6
= 166 mL / hr
Flow rate (Volume to be infused in 1 minute) = 166/60 = 2.767 mL / min
= 2.767 x 10 = 27.67 gtts / min
round to 28 gtts / min
Application : If you count 7 drops when you count
for 15 seconds, the IV infusion is CORRECT!
(7 gtts / 15 seconds)
53. Shortcut
For drop factor=10 gtts/mL,
2020 53
For Practice, but not for examinations!
Drops per minute
=
Volume (mL)
Time (minutes)
x Drop Factor (drops/ mL)
Drops per minute = x mL/hr x 10 drops/ mL
Drops per minute = x mL/60 min x 10 drops/ mL
= x / 6
If the prescription is given in x mL / hours,
For similar case: for drop factor = 10, divide 6
drop factor = 15, divide 4
drop factor = 20, divide 3
drop factor = 60, divide 1
54. Now…… for the same Example
An IV infusion of 1000 mL is prescribed to run for 6 hours. What Flow Rate should be infused
with a drop rate= 10?
54
Volume to be infused in 1 hour = 1000 / 6
= 166 mL / hr
Flow rate (Volume to be infused in 1 minute) = 166/6 = 27.67 gtts / min
round to 28 gtts / min
55. Half-life calculation
Eg. An antibiotics has a half life of 6 hours, 1st dose of drug is 500mg
6 hours later,
12 hours after 1st dose,
55
The half-life is defined as the amount of time required by 50%
of the drug to be eliminated from the body.
56. Half-life calculation
Eg. An antibiotics has a half life of 6 hours, 1st dose of drug is 500mg
6 hours later,
12 hours after 1st dose,
56
The half-life is defined as the amount of time required by 50%
of the drug to be eliminated from the body.
250mg remains in the body
57. Half-life calculation
Eg. An antibiotics has a half life of 6 hours, 1st dose of drug is 500mg
6 hours later,
12 hours after 1st dose,
57
The half-life is defined as the amount of time required by 50%
of the drug to be eliminated from the body.
125mg remains
250mg remains in the body
